- Email: [email protected]
Lymphatic Mapping and Sentinel Node Analysis in Colon Cancer
Comprehensive
Review
Lymphatic Mapping and Sentinel Node Analysis in Colon Cancer Steve R. Martinez, Anton J. Bilchik Abstract Accurate staging of colon cancer is prognostically and therapeutically important. By identifying those patients who would most benefit from adjuvant chemotherapy, accurate staging should decrease recurrence rates and improve overall survival. Lymphatic mapping and sentinel node analysis allow for a focused review of the lymph nodes, which are most likely to harbor a metastasis and may make ultrastaging techniques, such as immunohistochemistry and reverse-transcriptase polymerase chain reaction, more practical. The prognostic significance of micrometastatic disease detected via ultrastaging techniques remains controversial. Clinical Colorectal Cancer, Vol. 4, No. 5, 320-324, 2005 Key words: Colectomy, Immunohistochemistry, Laparoscopy, Prognosis, Reverse-transcriptase polymerase chain reaction, Staging
Introduction The sentinel node paradigm is based on the premise that lymphatic drainage from a primary organ site occurs in an orderly and progressive fashion. The sentinel node is the first node to receive lymphatic drainage from a primary anatomic site and is therefore the most likely node to harbor a metastatic malignancy. Although the intraoperative localization of lymphatics using radioactive gold colloid was used as early as 1953, it was Morton and colleagues who championed the sentinel node concept and established its clinical importance in melanoma.1 The technique was then successfully applied to breast cancer by Giuliano et al.2 Others have applied the technique to prostate, thyroid, lung, vulvar, esophageal, gastric, anal, and colorectal malignancies. The application of lymphatic mapping to colon cancer is philosophically different from its use in breast cancer or melanoma, in which identification of the sentinel node is used to predict the presence or absence of metastatic disease in the corresponding nodal basin in an effort to limit unnecessary lymphadenectomies. In breast cancer and melanoma, only patients with metastatic disease in the sentinel node undergo a formal node dissection. With colon cancer, however, no atJohn Wayne Cancer Institute, Santa Monica, CA Submitted: Jul 7, 2004; Revised: Aug 5, 2004; Accepted: Aug 5, 2004 Address for correspondence: Anton J. Bilchik, MD, PhD, John Wayne Cancer Institute, 2200 Santa Monica Blvd, Santa Monica, CA 90404 Fax: 310-449-5261; e-mail: [email protected]
tempt is made to limit the lymph node resection based on the presence or absence of metastatic disease in the sentinel node. In fact, by identifying aberrant or unexpected sites of lymphatic drainage, lymphatic mapping may lead to more radical lymphadenectomies. Colon cancer is the most common gastrointestinal malignancy in the United States and is the second most common cause of cancer mortality. According to estimates from the American Cancer Society, > 106,000 new cases were diagnosed in the United States in 2004 and approximately 57,000 Americans died from the disease.3 The proper staging of colon cancer provides information regarding the extent of primary organ involvement as well as spread to regional lymph nodes and more distant sites.4,5 Stage I/II colon carcinomas are distinguished from stage III cancers primarily by the absence of lymph node involvement. Survival rates for patients with stage I and II disease are 90% and 75%, respectively, whereas patients with stage III disease have a 5year survival rate of approximately 50%. Chemotherapy improves survival in as many as 33% of patients with stage III disease,6,7 but it has not been demonstrated to improve survival in stage I/II disease.6 Stage I/II disease is potentially cured by surgical resection alone. Despite this, 30% of these patients with node-negative disease will develop recurrent disease and die from colon cancer. The reasons for this are unclear but are likely multifactorial. One theory attributes the development of recurrent node-negative disease to the presence of residual nodal disease, as a result of inadequate lymphadenectomy or overlooked aberrant lymphatic drainage.
Electronic forwarding or copying is a violation of US and International Copyright Laws. Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by Cancer Information Group, ISSN #1533-0028, provided the appropriate fee is paid directly to Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923 USA 978-750-8400.
320 • Clinical Colorectal Cancer January 2005
Steve R. Martinez, Anton J. Bilchik Lymphatic mapping assists in the upstaging of colon cancer by helping to identify lymph nodes, particularly those that may be small or in aberrant locations and difficult to see. If we can more accurately identify patients with lymph node involvement, we may be able to better determine which patients would benefit most from adjuvant therapy. Intuitively, the more nodes that are recovered, the greater the likelihood of discovering an occult metastasis. There is no consensus on the number of nodes necessary for adequate staging. The American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC) recommend the examination of only 12 lymph nodes per specimen.4,5 Others have recommended harvesting > 12 nodes. In a review of 108 patients with stage II colon cancer, Burdy et al found that the recovery of < 14 uninvolved lymph nodes in the colectomy specimen was significantly associated with tumor recurrence.8 It may be possible to reliably stage colon cancer by examining ≥ 12 lymph nodes, but more nodes may need to be examined for greater predictive value. Joseph et al concluded that prediction of nodal status with an 85% certainty required examination of > 40 nodes for T1/2 lesions and ≥ 40 nodes for T3 lesions.9 Although > 40 nodes may be harvested from a properly resected specimen, thorough examination of these nodes would be costly and labor-intensive. Additionally, all harvested lymph nodes may not be identified and examined by the pathologist. Conventional methods of pathologic examination are subject to sampling error. Because as many as 70% of tumor-involved lymph nodes are < 0.5 cm in diameter,10 nodes that contain metastases often cannot be seen or palpated by the surgeon. Using standard techniques, < 1% of the lymph node is examined for metastases. Techniques have been developed that may reduce sampling error, such as multilevel sectioning, xylene-based fat clearance, cytokeratin immunohistochemistry (IHC), and reverse-transcriptase polymerase chain reaction (RT-PCR). The importance of using techniques beyond standard hematoxylin and eosin (H&E) staining to stage colon cancer was underscored by the revised guidelines of the AJCC and the UICC published in 2002.4,5 The revised staging guidelines define micrometastases and distinguish them from isolated tumor cells. This change in nomenclature reflects the growing, but as yet prospectively unproven, body of evidence that the presence of micrometastases and isolated tumor cells may have prognostic importance. With use of IHC, micrometastases may be identified in 10%-76% of cases that would not have been noted by H&E alone.11,12 It is unresolved whether IHC-detected cells within lymph nodes represent metastatic disease or reflect hyperplastic mesothelial cells, benign epithelial cells, or tumor cells that are shed from the primary mass during surgical manipulation but lack true metastatic potential. Broll et al examined the nodes of 32 patients with stage I/II colorectal carcinoma.13 With a median follow-up of 84 months, 33% of IHC-positive patients developed disease recurrence, as opposed to only 12% of patients with IHC-negative nodes. However, this difference in disease recurrence did not trans-
late into a difference in overall survival. Greenson et al used IHC for cytokeratin and TAG-72 to examine the lymph nodes of 50 patients with node-negative Dukes B colon cancer.14 Mortality within 66 months was 43% for patients with IHCpositive disease but only 3% for patients with IHC-negative disease. Although promising, several studies have failed to reveal a difference between patients with IHC-positive and IHC-negative lymph nodes with respect to disease recurrence or survival. Tschmelitsch et al used an anticytokeratin antibody to reexamine nodal tissue from 55 patients who had undergone surgical resection of stage II colon cancer and were followed up for ≥ 5 years.15 Those patients who developed disease recurrence had a lower rate of IHC-identified micrometastases (67%) than those who did not experience recurrence (84%). Reverse-transcriptase polymerase chain reaction is a technology that allows for the amplification of a known segment of RNA that codes for a protein of interest, eg, K-ras, p53, or carcinoembryonic antigen. Bilchik et al used a multimarker RT-PCR assay that incorporated uMAGE, c-MET, and B-hCG.12 This approach upstaged 46% of cases identified as node-negative by H&E and IHC. Similarly, Liefers et al used RT-PCR for carcinoembryonic antigen to study the nodes of 26 patients with node-negative colorectal cancer; 54% of cancers were upstaged.16 More important, the 5-year survival rate was 91% for those who had node-negative disease by RT-PCR compared with only 50% for those with node-positive disease by RT-PCR. These so-called ultrastaging techniques are promising but too costly and time-consuming for use on all nodes in a colectomy specimen. If the pathologist’s efforts could be concentrated on a few lymph nodes that are most likely to harbor a metastatic cancer, the potential to upstage cancer would be greatly increased without significantly increasing time and cost. Lymphatic mapping, by helping to identify high-risk lymph nodes, particularly those that may be small or in aberrant locations and difficult to see, would assist in the upstaging of colon cancer. Lymphatic mapping may allow an effective, focused pathologic ultrastaging review of ≥ 1 sentinel nodes without compromising standard pathologic assessment of nonsentinel nodes. Joosten et al published the first series of 50 patients with colon cancer who underwent lymphatic mapping and sentinel node analysis in 1999.17 The sentinel node was located with a 70% success rate using blue dye alone. Because a high false-negative rate was noted, however, the authors concluded that the technique was not a reliable method of staging colon cancer. Bilchik et al showed that lymphatic mapping could be applied successfully not only to colon cancer but to other gastrointestinal malignancies as well.12,18-21 Several methods of lymphatic mapping have been described.12,17-36 Mapping has been successfully performed before (in vivo) or after (ex vivo) en bloc resection of the tumor. Mapping may use a laparoscope or an open surgical technique; mapping agents include blue dye and/or radioactive colloid (Table 1).12,17-20,22-31,33-36
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Sentinel Node Mapping in Colon Cancer Table 1
Lymphatic Mapping in Colorectal Cancer: Sentinel Node Identification and Mapping Accuracy (False-Negative Rate)12,17-20,22-31,33-36 Number of Patients
Mapping Technique
Number of Patients with ≥ 1 Sentinel Node
Number of Patients with FalseNegative Sentinel Nodes
Joosten et al (1999)17
50
Blue dye, open colectomy
35 (70%)
12 (34%)
Wood et al (2000)22
50
Blue dye, open colectomy
47 (94%)
3 (6%)
(2000)30
86
Blue dye, open colectomy
85 (99%)
3 (3%)
Saha et al (2001)31
203
Blue dye, open colectomy
198 (99%)
8 (4%)
Study (Year)
Saha et al
Bilchik et
al (2001)12
40
Blue dye, open colectomy
40 (100%)
0
Esser et al (2001)24
31
Blue dye, open colectomy
18 (58%)
1 (5%)
Feig et al (2001)25
48
Blue dye, open colectomy
47 (98%)
10 (21%)
Merrie et al (2001)26
25
Blue dye, colloid, open colectomy
23 (88%)
10 (45%)
Paramo et al
(2001)28
35
Blue dye, open colectomy
25 (71%)
0
Wong et al (2001)34
26
Blue dye, open colectomy
24 (92%)
1 (4%)
Wood et al (2001)35
75
Blue dye, LAC, open colectomy
72 (96%)
4 (5%)
Wood et al (2001)36
11
Blue dye, LAC
11 (100%)
0
100
Blue dye, LAP, open colectomy
97 (97%)
5 (5%)
20
Blue dye, open colectomy
18 (90%)
1 (5%)
Bilchik et al
(2002)20
Bendavid et al (2002)23 Paramo et
al (2002)27
55
Blue dye, open colectomy
45 (82%)
1 (2%)
Patten et al (2002)29
43
Blue dye, colloid, open colectomy
41 (95%)
7 (17%)
Tsioulias et al (2002)33
14
Blue dye, LAC
14 (100%)
1 (7%)
Bilchik and Trocha (2003)18
30
Blue dye, LAC
30 (100%)
2 (7%)
120
Blue dye, colloid, open colectomy
97 (97%)
5 (4%)
Bilchik et
al (2003)19
Abbreviation: LAC = laparoscopic-assisted colectomy
Open in Vivo Technique The tumor is localized by visualization and palpation. Unnecessary manipulation of the mesentery and blood vessels is avoided to minimize lymphatic disruption. A tuberculin syringe is used to inject 0.5-1 mL of isosulfan blue dye subserosally in 4 quadrants around the tumor periphery (Figure 1).12 Blue afferent lymphatics are traced to the sentinel node, usually within 1-3 minutes of injection (Figure 2).12 Gentle dissection may be necessary to identify the blue-stained sentinel nodes in the mesentery. All blue nodes identified are marked with suture. Great care should be exercised in locating and marking all blue nodes, as aberrant lymphatic drainage has been noted in as many as 29% of cases.18,21 The colon and regional nodal basin are resected en bloc and submitted for pathologic review. Successful sentinel node localization varies widely, from 58%19 to 100%.14,15,28,31 At our institution, sentinel nodes are identified with a success rate of approximately 94%.
mum of 2 mL of isosulfan blue dye is injected in the subserosa around the tumor periphery in 4 quadrants. Sentinel nodes are found by tracing blue lymphatic channels to the draining lymph node. The rate of successful sentinel node identification ranges from 88%35 to 92%34 using this technique. However, because mapping is performed only after the specimen has been resected, it is impossible to identify aberrant lymphatic drainage to lymph nodes not included in a standard resection. The ex vivo technique may be performed by a surgeon or pathologist. It would be most advantageous to have the pathologist perform ex vivo mapping at smaller academic centers and community hospitals, in which the total number of lymphatic mapping cases may be small. In this way, the limited lymphatic mapping experience of several surgeons could be concentrated among a few pathologists in an attempt to overcome the learning curve. We have adopted a combination of in vivo and ex vivo techniques.35 If the sentinel node is not identified in vivo, ex vivo lymphatic mapping may be successful.
Ex Vivo Technique
Laparoscopic in Vivo Lymphatic Mapping
The colectomy specimen is taken immediately to a side table after routine en bloc resection. A pathologist or surgeon may perform lymphatic mapping. Wong et al described an ex vivo technique that involved cutting open the colon along the antimesenteric border and injecting vital blue dye submucosally.34 We adopted a modification of this technique. A maxi-
Patients are placed on the operating table supine or in the low lithotomy position. After laparoscopic abdominal exploration to confirm suitability for laparoscopic colon resection, the colon is mobilized only enough to confirm tumor location. This may be done through laparoscopic observation of tumor growth at the serosal surface or by noting the location of India
322 • Clinical Colorectal Cancer January 2005
Steve R. Martinez, Anton J. Bilchik Figure 1
Injection and Subserosal Injection Site12
Figure 2
Primary, Lymphatic, and Sentinel Lymph Nodes12
A tuberculin syringe is used to inject 1 mL of isosulfan blue dye subserosally in 4 quadrants around the tumor. Reprinted with permission from Bilchik et al. Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial. J Clin Oncol 2001; 19:1128-1136.
Soon after injection of blue dye, a blue-stained lymphatic channel (arrow) is followed to the bluestained sentinel lymph nodes (arrowheads), which are marked with a suture. Reprinted with permission from Bilchik et al. Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial. J Clin Oncol 2001; 19:1128-1136.
ink injected preoperatively at the time of colonoscopy. Prior polypectomy sites may be located with the aid of intraoperative colonoscopy. If this technique is used, isosulfan blue (1 mL) may be injected into the subserosa directly through a hand port, percutaneously via a spinal needle or with the aid of a colonoscope. Colonoscopic dye injection is reserved for those cases in which the tumor is not visible by the laparoscope. Blue afferent lymphatics are visualized laparoscopically and traced to the sentinel node or nodes, which are marked with clips or suture. The involved segment of colon and the regional nodes are resected via a minilaparotomy, and an anastomosis is created extracorporeally. This method of lymphatic mapping allows the surgeon to capitalize on the advantages of laparoscopic colon resection, such as decreased postoperative pain, shorter hospital stay, superior cosmetic result, and a quicker return to routine daily activities. Concerns regarding increased rates of local recurrence secondary to inadequate lymphadenectomy have not been substantiated in a randomized controlled study.37 Successful sentinel node localization is reported to be 100% in 3 series,18,33,36 with a false-negative rate ranging between 036 and 7%.18
then resected en bloc as usual. The specimen was placed on a standardized grid and gamma imaging was performed. Only then were lymph nodes dissected, with their coordinates noted as well as the presence or absence of blue dye. This technique of combining blue dye and radioactive colloid had an 88% success rate of sentinel node identification, but an unacceptably high 45% false-negative rate. Trocha et al used a combination of isosulfan blue and technetium-labeled sulfur colloid injected separately around the tumor periphery into the subserosa.32 Identification of blue nodes was done immediately in vivo; all blue nodes were marked with suture. Subsequently, a hand-held gamma probe was used to locate “hot” sentinel nodes. This technique identified ≥ 1 sentinel node in 98% of patients, with a false-negative rate of 6%.
Radioactive Tracer There is a wide range in the sentinel node identification and false-negative rates. This may be caused in part by a learning curve for the procedure. Alternatively, this may reflect the absence of a standardized method of sentinel node identification. The addition of a radioactive tracer to blue dye has improved the accuracy of lymphatic mapping and sentinel node localization in melanoma and breast cancer, and therefore was attempted in colon cancer. Merrie et al mixed 2 mL of patent blue dye with 40 MBq of technetium 99m colloidal antimony and injected 26 colon tumors subserosally.26 The colon and regional nodes were
Conclusion The advantages of lymphatic mapping and sentinel lymph node analysis are 3-fold. First, lymphatic mapping has been shown to increase the overall yield of lymph nodes harvested in a surgical specimen. Second, lymphatic mapping identifies aberrant routes of lymphatic drainage and allows for the inclusion of lymph nodes that might otherwise not be in the field of resection.18 Last, and central to the sentinel node concept, lymph nodes identified as sentinel include those that are most likely to harbor metastatic disease. Because the sentinel node accurately predicts the tumor status of the regional nodal basin, costly and time-consuming ultrastaging analysis is limited to those nodes most likely to contain metastatic disease. Lymphatic mapping and sentinel node analysis are thus suited to play an important role in the staging of colon adenocarcinoma.
Acknowledgements Supported in part by grant CA090848 from the National Cancer Institute and by funding from the Rod Fasone Memo-
Clinical Colorectal Cancer January 2005
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Sentinel Node Mapping in Colon Cancer rial Cancer Fund (Indianapolis, IN), the Henry L. Guenther Foundation (Los Angeles, CA), the William Randolph Hearst Foundation (San Francisco, CA), the family of Jeanne and Eric Li, the Davidow Charitable Fund (Los Angeles, CA), and the Harold J. McAlister Charitable Foundation (Los Angeles, CA).
References
1. Morton DL, Wen DR, Wong JH, et al. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg 1992; 127:392-399. 2. Giuliano AE, Kirgan DM, Guenther JM, et al. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 1994; 220:391-398. 3. Jemal A, Tiwari RC, Murray T, et al. Cancer statistics, 2004. CA Cancer J Clin 2004; 54:8-29. 4. Green FL, Page DL, Fleming ID, et al, eds. AJCC Cancer Staging Manual, 6th ed. New York: Springer Verlag, 2002. 5. Sobin LH, Wittekind C, eds. International Union Against Cancer (UICC). TNM Classification of Malignant Tumors, 6th ed. New York: Wiley, 2002. 6. Cohen AM, Kelsen D, Saltz L, et al. Adjuvant therapy for colorectal cancer. Curr Probl Cancer 1998; 22:5-65. 7. Moertel CG, Fleming TR, MacDonald JS, et al. Levamisole and fluorouracil for adjuvant therapy of resected colon cancinoma. N Engl J Med 1990; 322:352-358. 8. Burdy G, Panis Y, Alves A, et al. Identifying patients with T3-T4 node-negative colon cancer at high risk of recurrence. Dis Colon Rectum 2001; 44:1682-1688. 9. Joseph NE, Sigurdson ER, Hanlon AL, et al. Accuracy of determining nodal negativity in colorectal cancer on the basis of the number of nodes retrieved on resection. Ann Surg Oncol 2003; 10:213-218. 10. Rodriguez-Bigas MA, Maamoun S, Weber TK, et al. Clinical significance of colorectal cancer: metastases in lymph nodes < 5mm in size. Ann Surg Oncol 1996; 3:124-130. 11. Feezor RJ, Copeland EM, Hochwald SN. Significance of micrometastases in colorectal cancer. Ann Surg Oncol 2002; 9:944-953. 12. Bilchik AJ, Saha S, Wiese D, et al. Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial. J Clin Oncol 2001; 19:1128-1136. 13. Broll R, Schauer V, Schimmelpenning H, et al. Prognostic relevance of occult tumor cells in lymph nodes of colorectal carcinomas: an immunohistochemical study. Dis Colon Rectum 1997; 40:1465-1471. 14. Greenson JK, Isenhart CE, Rice R, et al. Identification of occult metastases in pericolic lymph nodes of Dukes B colorectal cancer patients using monoclonal antibodies against cytokeratin and CC49. Correlation with long term survival. Cancer 1994; 73:563-569. 15. Tschmelitsch J, Klimstra DS, Cohen AM. Lymph node micrometastases do not predict relapse in stage II colon cancer. Ann Surg Oncol 2000; 7:601-608. 16. Liefers GJ, Cleton-Jansen AM, van de Velde CJ, et al. Micrometastases and survival in stage II colorectal cancer. N Engl J Med 1998; 339:223-228. 17. Joosten JJ, Strobbe LJ, Wauters CA, et al. Intraoperative lymphatic mapping and the sentinel node concept in colorectal carcinoma. Br J Surg 1999; 86:482-486. 18. Bilchik AJ, Trocha SD. Lymphatic mapping and sentinel node analy-
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19. 20. 21.
22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37.
sis to optimize laparoscopic resection and staging of colorectal cancer: an update. Cancer Control 2003; 10:219-223. Bilchik AJ, Nora DT, Sobin LH, et al. Effect of lymphatic mapping on the new tumor-node-metastasis classification for colorectal cancer. J Clin Oncol 2003; 21:668-672. Bilchik AJ, Nora D, Tollenaar RAEM, et al. Ultrastaging of early colon cancer using lymphatic mapping and molecular analysis. Eur J Cancer 2002; 38:977-985. Bilchik AJ, Saha S, Tsioulias GJ, et al. Aberrant drainage and missed micrometastases: the value of lymphatic mapping and focused analysis of sentinel lymph nodes in gastrointestinal neoplasms. Ann Surg Oncol 2001; 8:82-85. Wood TF, Tsioulias GJ, Morton DL, et al. Focused examination of sentinel lymph nodes upstages early colorectal carcinoma. Am Surg 2000; 66:998-1003. Bendavid Y, Latulippe JF, Younan RJ, et al. Phase I study on sentinel lymph node mapping in colon cancer: a preliminary report. J Surg Oncol 2002; 79:81-85. Esser S, Reilly WT, Riley LB, et al. The role of sentinel lymph node mapping in staging of colon and rectal cancer. Dis Colon Rectum 2001; 44:850-856. Feig BW, Curley S, Lucci A, et al. A caution regarding lymphatic mapping in patients with colon cancer. Am J Surg 2001; 182:707-712. Merrie AE, van Rij AM, Phillips LV, et al. Diagnostic use of the sentinel node in colon cancer. Dis Colon Rectum 2001; 44:410417. Paramo JC, Summerall J, Poppiti R, et al. Validation of sentinel node mapping in patients with colon cancer. Ann Surg Oncol 2002; 9:550554. Paramo JC, Summerall J, Wilson C, et al. Intraoperative sentinel lymph node mapping in patients with colon cancer. Am J Surg 2001; 182:40-43. Patten LC, Berger DH, Cleary KR, et al. A prospective evaluation of radiocolloid and immunohistochemical staining in colon cancer lymphatic mapping. Ann Surg Oncol 2002; 9:S72. Saha S, Bilchik A, Wiese D, et al. Ultrastaging of colorectal cancer by sentinal lymph node mapping technique - a multicenter trial. Ann Surg Oncol 2001; 9(suppl):94S-98S. Saha S, Nora D, Wong JH, et al. Sentinel lymph node mapping in colorectal cancer—a review. Surg Clin North Am 2000; 80:1811-1819. Trocha SD, Nora DT, Saha SS, et al. Combination probe and dye-directed lymphatic mapping detects micrometastases in early colorectal cancer. J Gastrointest Surg 2003; 7:340-346. Tsioulias GJ, Wood TF, Spirt M, et al. A novel lymphatic mapping technique to improve localization and staging of early colon cancer during laparoscopic colectomy. Am Surg 2002; 68:561-565. Wong JH, Steineman S, Calderia C, et al. Ex vivo sentinel node mapping in carcinoma of the colon and rectum. Ann Surg 2001; 233:515521. Wood TF, Saha S, Morton DL, et al. Validation of lymphatic mapping in colorectal cancer: in vivo, ex vivo and laparoscopic techniques. Ann Surg Oncol 2001; 8:150-157. Wood TF, Spirt M, Rangel D, et al. Lymphatic mapping improves staging during laparoscopic colectomy for cancer. Surg Endosc 2001; 15:715-719. Clinical Outcomes of Surgical Therapy Study Group. A comparison of laparoscopically assisted and open colectomy for colon cancer. N Engl J Med 2004; 350:2050-2059.
Review
Lymphatic Mapping and Sentinel Node Analysis in Colon Cancer Steve R. Martinez, Anton J. Bilchik Abstract Accurate staging of colon cancer is prognostically and therapeutically important. By identifying those patients who would most benefit from adjuvant chemotherapy, accurate staging should decrease recurrence rates and improve overall survival. Lymphatic mapping and sentinel node analysis allow for a focused review of the lymph nodes, which are most likely to harbor a metastasis and may make ultrastaging techniques, such as immunohistochemistry and reverse-transcriptase polymerase chain reaction, more practical. The prognostic significance of micrometastatic disease detected via ultrastaging techniques remains controversial. Clinical Colorectal Cancer, Vol. 4, No. 5, 320-324, 2005 Key words: Colectomy, Immunohistochemistry, Laparoscopy, Prognosis, Reverse-transcriptase polymerase chain reaction, Staging
Introduction The sentinel node paradigm is based on the premise that lymphatic drainage from a primary organ site occurs in an orderly and progressive fashion. The sentinel node is the first node to receive lymphatic drainage from a primary anatomic site and is therefore the most likely node to harbor a metastatic malignancy. Although the intraoperative localization of lymphatics using radioactive gold colloid was used as early as 1953, it was Morton and colleagues who championed the sentinel node concept and established its clinical importance in melanoma.1 The technique was then successfully applied to breast cancer by Giuliano et al.2 Others have applied the technique to prostate, thyroid, lung, vulvar, esophageal, gastric, anal, and colorectal malignancies. The application of lymphatic mapping to colon cancer is philosophically different from its use in breast cancer or melanoma, in which identification of the sentinel node is used to predict the presence or absence of metastatic disease in the corresponding nodal basin in an effort to limit unnecessary lymphadenectomies. In breast cancer and melanoma, only patients with metastatic disease in the sentinel node undergo a formal node dissection. With colon cancer, however, no atJohn Wayne Cancer Institute, Santa Monica, CA Submitted: Jul 7, 2004; Revised: Aug 5, 2004; Accepted: Aug 5, 2004 Address for correspondence: Anton J. Bilchik, MD, PhD, John Wayne Cancer Institute, 2200 Santa Monica Blvd, Santa Monica, CA 90404 Fax: 310-449-5261; e-mail: [email protected]
tempt is made to limit the lymph node resection based on the presence or absence of metastatic disease in the sentinel node. In fact, by identifying aberrant or unexpected sites of lymphatic drainage, lymphatic mapping may lead to more radical lymphadenectomies. Colon cancer is the most common gastrointestinal malignancy in the United States and is the second most common cause of cancer mortality. According to estimates from the American Cancer Society, > 106,000 new cases were diagnosed in the United States in 2004 and approximately 57,000 Americans died from the disease.3 The proper staging of colon cancer provides information regarding the extent of primary organ involvement as well as spread to regional lymph nodes and more distant sites.4,5 Stage I/II colon carcinomas are distinguished from stage III cancers primarily by the absence of lymph node involvement. Survival rates for patients with stage I and II disease are 90% and 75%, respectively, whereas patients with stage III disease have a 5year survival rate of approximately 50%. Chemotherapy improves survival in as many as 33% of patients with stage III disease,6,7 but it has not been demonstrated to improve survival in stage I/II disease.6 Stage I/II disease is potentially cured by surgical resection alone. Despite this, 30% of these patients with node-negative disease will develop recurrent disease and die from colon cancer. The reasons for this are unclear but are likely multifactorial. One theory attributes the development of recurrent node-negative disease to the presence of residual nodal disease, as a result of inadequate lymphadenectomy or overlooked aberrant lymphatic drainage.
Electronic forwarding or copying is a violation of US and International Copyright Laws. Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by Cancer Information Group, ISSN #1533-0028, provided the appropriate fee is paid directly to Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923 USA 978-750-8400.
320 • Clinical Colorectal Cancer January 2005
Steve R. Martinez, Anton J. Bilchik Lymphatic mapping assists in the upstaging of colon cancer by helping to identify lymph nodes, particularly those that may be small or in aberrant locations and difficult to see. If we can more accurately identify patients with lymph node involvement, we may be able to better determine which patients would benefit most from adjuvant therapy. Intuitively, the more nodes that are recovered, the greater the likelihood of discovering an occult metastasis. There is no consensus on the number of nodes necessary for adequate staging. The American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC) recommend the examination of only 12 lymph nodes per specimen.4,5 Others have recommended harvesting > 12 nodes. In a review of 108 patients with stage II colon cancer, Burdy et al found that the recovery of < 14 uninvolved lymph nodes in the colectomy specimen was significantly associated with tumor recurrence.8 It may be possible to reliably stage colon cancer by examining ≥ 12 lymph nodes, but more nodes may need to be examined for greater predictive value. Joseph et al concluded that prediction of nodal status with an 85% certainty required examination of > 40 nodes for T1/2 lesions and ≥ 40 nodes for T3 lesions.9 Although > 40 nodes may be harvested from a properly resected specimen, thorough examination of these nodes would be costly and labor-intensive. Additionally, all harvested lymph nodes may not be identified and examined by the pathologist. Conventional methods of pathologic examination are subject to sampling error. Because as many as 70% of tumor-involved lymph nodes are < 0.5 cm in diameter,10 nodes that contain metastases often cannot be seen or palpated by the surgeon. Using standard techniques, < 1% of the lymph node is examined for metastases. Techniques have been developed that may reduce sampling error, such as multilevel sectioning, xylene-based fat clearance, cytokeratin immunohistochemistry (IHC), and reverse-transcriptase polymerase chain reaction (RT-PCR). The importance of using techniques beyond standard hematoxylin and eosin (H&E) staining to stage colon cancer was underscored by the revised guidelines of the AJCC and the UICC published in 2002.4,5 The revised staging guidelines define micrometastases and distinguish them from isolated tumor cells. This change in nomenclature reflects the growing, but as yet prospectively unproven, body of evidence that the presence of micrometastases and isolated tumor cells may have prognostic importance. With use of IHC, micrometastases may be identified in 10%-76% of cases that would not have been noted by H&E alone.11,12 It is unresolved whether IHC-detected cells within lymph nodes represent metastatic disease or reflect hyperplastic mesothelial cells, benign epithelial cells, or tumor cells that are shed from the primary mass during surgical manipulation but lack true metastatic potential. Broll et al examined the nodes of 32 patients with stage I/II colorectal carcinoma.13 With a median follow-up of 84 months, 33% of IHC-positive patients developed disease recurrence, as opposed to only 12% of patients with IHC-negative nodes. However, this difference in disease recurrence did not trans-
late into a difference in overall survival. Greenson et al used IHC for cytokeratin and TAG-72 to examine the lymph nodes of 50 patients with node-negative Dukes B colon cancer.14 Mortality within 66 months was 43% for patients with IHCpositive disease but only 3% for patients with IHC-negative disease. Although promising, several studies have failed to reveal a difference between patients with IHC-positive and IHC-negative lymph nodes with respect to disease recurrence or survival. Tschmelitsch et al used an anticytokeratin antibody to reexamine nodal tissue from 55 patients who had undergone surgical resection of stage II colon cancer and were followed up for ≥ 5 years.15 Those patients who developed disease recurrence had a lower rate of IHC-identified micrometastases (67%) than those who did not experience recurrence (84%). Reverse-transcriptase polymerase chain reaction is a technology that allows for the amplification of a known segment of RNA that codes for a protein of interest, eg, K-ras, p53, or carcinoembryonic antigen. Bilchik et al used a multimarker RT-PCR assay that incorporated uMAGE, c-MET, and B-hCG.12 This approach upstaged 46% of cases identified as node-negative by H&E and IHC. Similarly, Liefers et al used RT-PCR for carcinoembryonic antigen to study the nodes of 26 patients with node-negative colorectal cancer; 54% of cancers were upstaged.16 More important, the 5-year survival rate was 91% for those who had node-negative disease by RT-PCR compared with only 50% for those with node-positive disease by RT-PCR. These so-called ultrastaging techniques are promising but too costly and time-consuming for use on all nodes in a colectomy specimen. If the pathologist’s efforts could be concentrated on a few lymph nodes that are most likely to harbor a metastatic cancer, the potential to upstage cancer would be greatly increased without significantly increasing time and cost. Lymphatic mapping, by helping to identify high-risk lymph nodes, particularly those that may be small or in aberrant locations and difficult to see, would assist in the upstaging of colon cancer. Lymphatic mapping may allow an effective, focused pathologic ultrastaging review of ≥ 1 sentinel nodes without compromising standard pathologic assessment of nonsentinel nodes. Joosten et al published the first series of 50 patients with colon cancer who underwent lymphatic mapping and sentinel node analysis in 1999.17 The sentinel node was located with a 70% success rate using blue dye alone. Because a high false-negative rate was noted, however, the authors concluded that the technique was not a reliable method of staging colon cancer. Bilchik et al showed that lymphatic mapping could be applied successfully not only to colon cancer but to other gastrointestinal malignancies as well.12,18-21 Several methods of lymphatic mapping have been described.12,17-36 Mapping has been successfully performed before (in vivo) or after (ex vivo) en bloc resection of the tumor. Mapping may use a laparoscope or an open surgical technique; mapping agents include blue dye and/or radioactive colloid (Table 1).12,17-20,22-31,33-36
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Sentinel Node Mapping in Colon Cancer Table 1
Lymphatic Mapping in Colorectal Cancer: Sentinel Node Identification and Mapping Accuracy (False-Negative Rate)12,17-20,22-31,33-36 Number of Patients
Mapping Technique
Number of Patients with ≥ 1 Sentinel Node
Number of Patients with FalseNegative Sentinel Nodes
Joosten et al (1999)17
50
Blue dye, open colectomy
35 (70%)
12 (34%)
Wood et al (2000)22
50
Blue dye, open colectomy
47 (94%)
3 (6%)
(2000)30
86
Blue dye, open colectomy
85 (99%)
3 (3%)
Saha et al (2001)31
203
Blue dye, open colectomy
198 (99%)
8 (4%)
Study (Year)
Saha et al
Bilchik et
al (2001)12
40
Blue dye, open colectomy
40 (100%)
0
Esser et al (2001)24
31
Blue dye, open colectomy
18 (58%)
1 (5%)
Feig et al (2001)25
48
Blue dye, open colectomy
47 (98%)
10 (21%)
Merrie et al (2001)26
25
Blue dye, colloid, open colectomy
23 (88%)
10 (45%)
Paramo et al
(2001)28
35
Blue dye, open colectomy
25 (71%)
0
Wong et al (2001)34
26
Blue dye, open colectomy
24 (92%)
1 (4%)
Wood et al (2001)35
75
Blue dye, LAC, open colectomy
72 (96%)
4 (5%)
Wood et al (2001)36
11
Blue dye, LAC
11 (100%)
0
100
Blue dye, LAP, open colectomy
97 (97%)
5 (5%)
20
Blue dye, open colectomy
18 (90%)
1 (5%)
Bilchik et al
(2002)20
Bendavid et al (2002)23 Paramo et
al (2002)27
55
Blue dye, open colectomy
45 (82%)
1 (2%)
Patten et al (2002)29
43
Blue dye, colloid, open colectomy
41 (95%)
7 (17%)
Tsioulias et al (2002)33
14
Blue dye, LAC
14 (100%)
1 (7%)
Bilchik and Trocha (2003)18
30
Blue dye, LAC
30 (100%)
2 (7%)
120
Blue dye, colloid, open colectomy
97 (97%)
5 (4%)
Bilchik et
al (2003)19
Abbreviation: LAC = laparoscopic-assisted colectomy
Open in Vivo Technique The tumor is localized by visualization and palpation. Unnecessary manipulation of the mesentery and blood vessels is avoided to minimize lymphatic disruption. A tuberculin syringe is used to inject 0.5-1 mL of isosulfan blue dye subserosally in 4 quadrants around the tumor periphery (Figure 1).12 Blue afferent lymphatics are traced to the sentinel node, usually within 1-3 minutes of injection (Figure 2).12 Gentle dissection may be necessary to identify the blue-stained sentinel nodes in the mesentery. All blue nodes identified are marked with suture. Great care should be exercised in locating and marking all blue nodes, as aberrant lymphatic drainage has been noted in as many as 29% of cases.18,21 The colon and regional nodal basin are resected en bloc and submitted for pathologic review. Successful sentinel node localization varies widely, from 58%19 to 100%.14,15,28,31 At our institution, sentinel nodes are identified with a success rate of approximately 94%.
mum of 2 mL of isosulfan blue dye is injected in the subserosa around the tumor periphery in 4 quadrants. Sentinel nodes are found by tracing blue lymphatic channels to the draining lymph node. The rate of successful sentinel node identification ranges from 88%35 to 92%34 using this technique. However, because mapping is performed only after the specimen has been resected, it is impossible to identify aberrant lymphatic drainage to lymph nodes not included in a standard resection. The ex vivo technique may be performed by a surgeon or pathologist. It would be most advantageous to have the pathologist perform ex vivo mapping at smaller academic centers and community hospitals, in which the total number of lymphatic mapping cases may be small. In this way, the limited lymphatic mapping experience of several surgeons could be concentrated among a few pathologists in an attempt to overcome the learning curve. We have adopted a combination of in vivo and ex vivo techniques.35 If the sentinel node is not identified in vivo, ex vivo lymphatic mapping may be successful.
Ex Vivo Technique
Laparoscopic in Vivo Lymphatic Mapping
The colectomy specimen is taken immediately to a side table after routine en bloc resection. A pathologist or surgeon may perform lymphatic mapping. Wong et al described an ex vivo technique that involved cutting open the colon along the antimesenteric border and injecting vital blue dye submucosally.34 We adopted a modification of this technique. A maxi-
Patients are placed on the operating table supine or in the low lithotomy position. After laparoscopic abdominal exploration to confirm suitability for laparoscopic colon resection, the colon is mobilized only enough to confirm tumor location. This may be done through laparoscopic observation of tumor growth at the serosal surface or by noting the location of India
322 • Clinical Colorectal Cancer January 2005
Steve R. Martinez, Anton J. Bilchik Figure 1
Injection and Subserosal Injection Site12
Figure 2
Primary, Lymphatic, and Sentinel Lymph Nodes12
A tuberculin syringe is used to inject 1 mL of isosulfan blue dye subserosally in 4 quadrants around the tumor. Reprinted with permission from Bilchik et al. Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial. J Clin Oncol 2001; 19:1128-1136.
Soon after injection of blue dye, a blue-stained lymphatic channel (arrow) is followed to the bluestained sentinel lymph nodes (arrowheads), which are marked with a suture. Reprinted with permission from Bilchik et al. Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial. J Clin Oncol 2001; 19:1128-1136.
ink injected preoperatively at the time of colonoscopy. Prior polypectomy sites may be located with the aid of intraoperative colonoscopy. If this technique is used, isosulfan blue (1 mL) may be injected into the subserosa directly through a hand port, percutaneously via a spinal needle or with the aid of a colonoscope. Colonoscopic dye injection is reserved for those cases in which the tumor is not visible by the laparoscope. Blue afferent lymphatics are visualized laparoscopically and traced to the sentinel node or nodes, which are marked with clips or suture. The involved segment of colon and the regional nodes are resected via a minilaparotomy, and an anastomosis is created extracorporeally. This method of lymphatic mapping allows the surgeon to capitalize on the advantages of laparoscopic colon resection, such as decreased postoperative pain, shorter hospital stay, superior cosmetic result, and a quicker return to routine daily activities. Concerns regarding increased rates of local recurrence secondary to inadequate lymphadenectomy have not been substantiated in a randomized controlled study.37 Successful sentinel node localization is reported to be 100% in 3 series,18,33,36 with a false-negative rate ranging between 036 and 7%.18
then resected en bloc as usual. The specimen was placed on a standardized grid and gamma imaging was performed. Only then were lymph nodes dissected, with their coordinates noted as well as the presence or absence of blue dye. This technique of combining blue dye and radioactive colloid had an 88% success rate of sentinel node identification, but an unacceptably high 45% false-negative rate. Trocha et al used a combination of isosulfan blue and technetium-labeled sulfur colloid injected separately around the tumor periphery into the subserosa.32 Identification of blue nodes was done immediately in vivo; all blue nodes were marked with suture. Subsequently, a hand-held gamma probe was used to locate “hot” sentinel nodes. This technique identified ≥ 1 sentinel node in 98% of patients, with a false-negative rate of 6%.
Radioactive Tracer There is a wide range in the sentinel node identification and false-negative rates. This may be caused in part by a learning curve for the procedure. Alternatively, this may reflect the absence of a standardized method of sentinel node identification. The addition of a radioactive tracer to blue dye has improved the accuracy of lymphatic mapping and sentinel node localization in melanoma and breast cancer, and therefore was attempted in colon cancer. Merrie et al mixed 2 mL of patent blue dye with 40 MBq of technetium 99m colloidal antimony and injected 26 colon tumors subserosally.26 The colon and regional nodes were
Conclusion The advantages of lymphatic mapping and sentinel lymph node analysis are 3-fold. First, lymphatic mapping has been shown to increase the overall yield of lymph nodes harvested in a surgical specimen. Second, lymphatic mapping identifies aberrant routes of lymphatic drainage and allows for the inclusion of lymph nodes that might otherwise not be in the field of resection.18 Last, and central to the sentinel node concept, lymph nodes identified as sentinel include those that are most likely to harbor metastatic disease. Because the sentinel node accurately predicts the tumor status of the regional nodal basin, costly and time-consuming ultrastaging analysis is limited to those nodes most likely to contain metastatic disease. Lymphatic mapping and sentinel node analysis are thus suited to play an important role in the staging of colon adenocarcinoma.
Acknowledgements Supported in part by grant CA090848 from the National Cancer Institute and by funding from the Rod Fasone Memo-
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Sentinel Node Mapping in Colon Cancer rial Cancer Fund (Indianapolis, IN), the Henry L. Guenther Foundation (Los Angeles, CA), the William Randolph Hearst Foundation (San Francisco, CA), the family of Jeanne and Eric Li, the Davidow Charitable Fund (Los Angeles, CA), and the Harold J. McAlister Charitable Foundation (Los Angeles, CA).
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