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Recent developments in the surgical management of rectal carcinoma
Recent Developments in the Surgical Management of Rectal Carcinoma Herbert C. Hoover,Jr
he past decade has witnessed some revolutionary changes in the surgical management of rectal cancer, especially evident in the middle to lower rectal lesions. In this article, we focus on three significant developments: (1) the importance of mesorectal resection, (2) mobilization of the small bowel when postoperative radiation therapy is anticipated, and (3) the role ofcoloanal anastomosis.
T
Mesorectal Resection The introduction of the circular stapler has made sphincter-sparing resection of middle to lower rectal cancer considerably easier and safer for most surgeons. Fewer patients today require abdominoperiheal resection and a permanent abdominal stoma. Most studies suggest that local recurrence and survival rates have not been adversely affected by the trend toward sphincter preservation as long as an adequate resection can be accomplished. I Just what represents an acceptably wide resection remains debatable, but most would agree that a distal margin of 2 cm is adequate for most cases. A less well accepted or less widely known concept is the importance of a sharp dissection of the entire mesorectum in patients with potentially curable middle to lower rectal cancers. The British, particularly Heald et al, 2,3 have led the way in stressing the great importance of the mesorectum in rectal cancer. Their careful pathologic studies have clearly shown that lymphatic spread, although rarely beyond 1 to 2 cm intramurally, can be up to 5 cm distal in the mesorectum. The conventional blunt mobilization of the posterior rectum is discouraged for fear that tumor lymphatics or veins could be torn, or that the tumor itself could be inadvertently exposed. Sharp dissection would reasonably be expected to be less traumatic. Heald has stressed his conviction that distal spread of rectal From the Department of Surgical Oncology Research, Massachusetts GeneralHospital, Harvard Medical School, Boston. Address reprint requests to Herbert C. Hoover, Jr, MD, Surgical Ontology, Cox-l, Massachusetts GeneralHospital, Boston, ?vLet02114. Copyright 9 1993by HdB. Sounders Company 1053-4296/93 / 0301-0002505.00/0 8
cancer is often initially confined to the mesorectal tissues, and that all middle to lower rectal cancers should have complete removal of the mesorectum to the levators if the tumor does not invade the levators or sphincters and if sphincter preservation is planned (Fig 1). The conventional resection that strives for a 2-cm distal margin often "cones" down to the rectal wall distal to the lesion, leaving considerable mesorecturn. Using a combination of sharp dissection and total mesorecta] resection, Heald has reported 3 a remarkably low intrapelvic recurrence rate of 2.6%, with no staple-line recurrences in 115 patients having an anterior resection with a low anastomosis at a mean follow-up of 4.2 years. Thirty-nine patients had mural resection margins of <2.5 cms, and 69 had anastomoses below 5 cm above the anal verge. This low recurrence rate was achieved without any adjuvant therapy. With the wide variability in extent of mesorectal tissue excision among surgeons, or even within a single surgeon's practice, depending on the patient's body build and pelvic anatomy, studies evaluating results in cooperative trials with or without irradiation are impossible to interpret in terms of the importance of surgical versus radiation effect on the outcome. Based on the generally accepted fact that radiation therapy reduces the incidence of pelvic recurrences, 4,5 one would reason that a combination of wide mesorectal resection and radiation therapy would offer the best possible therapy, but this has not been adequately studied. With his data, Heald makes a legitimate argument that a proper surgical resection obviates the need for radiation therapy in all but the most advanced rectal cancers. In the United States, most rectal resections are performed by surgeons less experienced than Heald in the method of mesorectal resection, and few probably are as radical in their approach. Consequently, until more data are available from larger series at other institutions, we should not abandon our current philosophy relative to pelvic irradiation for rectal cancers that are transmural and/or spread to pelvic lymph nodes. Ideally, a prospectively randomized trial between
Seminars in Radiation Oncology, Vol3, No 1 (January), 1993:pp 8-12
SurgicalManagementofRectal Carcinoma
Line of excision includes mesorectum
",a
Site of tumour deposits in Case 6
F i g u r e 1. The suggested plane of excision is shown diagrammatically by the dashed line. (Reprinted by permission of the publishers, Butterworth-Heineman Ltd]) conventional rectal resection that leaves the distal mesorectum intact plus radiation therapy should be compared with complete mesorectal resection without radiation therapy. Such a trial would be difficult because the advocates of wide mesorectal resection with or without radiation therapy and those who perform a conventional resection and use radiation therapy are often equally sure of the merit of their approach. In the absence of such data, both a wide mesorectal resection and pelvic irradiation are probably the ideal therapy tbr patients with transmural extension or involved pelvic l?anph nodes. A related issue of considerable importance is the extent of lateral dissection of rectal cancer. By whole-mount sections of the entire operative specimen examined by transverse slicing, Quirke 6 showed spread of rectal adenocarcinoma to the lateral resection margin in 14 of 52 patients (27%). Twelve of the 14 proceeded to local pelvic recurrence. A maximally wide lateral margin is achieved by sharp dissection along the lateral pelvic side wall, with suturing of transversed vessels rather than the commonly used method of clamping and tying, which compromises the lateral margin. This applies primarily to bulky tumors of the middle to lower rectum.
Mobilization of the Small Bowel for Postoperative Radiation Therapy Radiation injury to loops of small bowel fixed in the pelvis after rectal resection is perhaps the most serious complication in patients receiving pelvic irradiation. It occurs in 5% to 15% of patients. 7Although
9
modern radiation techniques have lowered the frequency with which this complication is clinically significant, surgeons should attempt to exclude the small bowel from the pelvis in all patients that will be receiving postoperative radiation therapy. If the mesorectum and pelvic peritoneum are resected along with the rectum, closure of the pelvic peritoneum is not possible, and the small bowel will descend to fill the pelvis. It quickly becomes adherent and cannot be effectively displaced even by a steep Trendelenburg or jackknife position during radiation therapy. Preventive procedures need to be performed at the end of the rectal procedure before abdominal closure. A number of innovative procedures have been developed, such as an omentoplasty to the pelvis, suturing the urinary bladder to the pelvic presacral fascia, the use of a mammary prosthesis, and the use of absorbable mesh to separate the pelvic and abdominal cavities. Omentoplasty and/or a mesh sling currently serve well in most patients and will be described in detail. Omentoplasty
Patients who have not had procedures of the upper abdomen that included partial or full omentectomy usually have adequate omentum to fill the pelvis if mobilized adequately. The obvious advantages are its autologous nature and its rich vasculature, which can potentially aid in preventing anastomotic leaks in the pelvis or help to heal the perineal closure after an abdominoperineal resection. Pelvic dead space is filled, which theoretically minimizes the likelihood of a pelvic abscess. However, there have been no studies that have definitively shown that the entire small bowel can be kept out of the pelvic cavity with this technique. The omentum should be fully mobilized off the greater curvature of the stomach, being careful to incorporate the gastroepiploic vessels within the omental pedicle. It can then be brought down either the left or the right gutter to fill the pelvis fully or nearly so in most patients. Especially thin patients may have an inadequate omentum to satisfactorily fill the pelvic space, and an alternative procedure should be used in those patients. The omentum should be secured to the peritoneum at the pelvic inlet and all the way around to prevent any loops of small bowel from entering the pelvis and defeating the purpose of the effort. Complications should be rare, although one must be very careful with hemostasis in this well-vascularized organ. Caution should be exercised in prevent-
10
Her&rt C Hoover,Jr.
ing ureteral, vascular, or neurologic injury while securing the omentum in the peMs. Absorbable
Mesh Dam
In patients with an inadequate omentum to flit the pelvis, an alternative is to separate the abdominal and peMc cavities by suturing into place a dam of absorbable mesh. Polyglycolic acid mesh has been used successfully in several reports 8-1~in both animals and humans, and is probably the prosthetic material of choice. Its degradation properties are such that its dissolution requires 2 to 3 months, preventing the small bowel from descending into the pelvis until well after radiation therapy is completed. The technical aspects of the mesh dam or intestinal sling procedure have been well outlined by Devereaux. I~ Obviously, this method leaves a large pelvic dead space. Ideally, it could be combined with omentoplasty when the omentum is inadequate to totally fill the pelvis in an effort to eliminate as much dead space as possible. This is especially important when there is a low anastomosis in the pelvis and is of less concern after an abdominoperineal resection. In 60 patients, Devereux reported I~ a mean total dose of pelvic irradiation of 5,500 rad. At 28 months of mean follow-up, there were no cases of radiation enteritis, small bowel obstruction, fistula or intraabdominal sepsis. Prolonged ileus was the only complication noted. Four patients reexplored 6 to 12 months postoperatively had no evidence of mesh present and no mesh-related adhesions such as a "cocoon" surrounding the small bowel. My limited experience has shown similar findings. This technique can be enthusiastically recommended for use in selected patients
)
where high-dose postoperative radiation therapy is definitely indicated.
Role of Coloanal A n a s t o m o s e s in Rectal Cancers The improvements in the circular staplers now allow a safe anastomosis tovery low levels in the rectum or even to the anus itself. Experience has shown that anal continence depends on maintenance of the anal sphincter itself, but does not require any rectal reservoir. Most data suggest that a 2-cm distal mural margin is adequate in the resection of rectal cancers. Therefore, selective rectal cancers that are at least 2 cm from the anal verge can be resected with an adequate margin and continuity and continence restored by means ofa coloanal anastomosis, achieved either by a staple or hand-sewn technique. Theoretically, with today's approaches, abdominoperineal resection can be limited to patients with invasion of the pelvic floor or anal sphincter. Numerous studies ll-17 now suggest that local control and cure are not compromised by these sphincter-sparing approaches in patients with tumors that are not locally extensive. The concept for coloanal anastomosis was developed by Soave Is in 1964 when he described a rectal mucosectomy combined with an endorectal coloanal sleeve anastomosis for the treatment of Hirschsprung's disease. In 1972, Parks m used a similar procedure for benign rectal conditions in the adult and reported its use for malignancies in 1982.u Parks' technique has been altered by various surgeons but still serves as the basis for this approach.
-~
,
Figure 2. (Left) A solution of adrenaline in normal saline (l:300,000) is injected into the submucosa of the rectal stump. (Right) The columnar mucosa is dissected off the submucosa above the dentate line.
SurgicalManagementofRectalCamnoma
11
F i g u r e 3. (Left) The circular muscle of the upper anal canal and rectal stump can be seen. (Right) The retractor is repositioned to expose the entire circumference in about three maneuvers.
Important technical details include division of the inferior mesenteric vessels at their origin to allow an adequate length of mesocolon for a tension-free anastomosis. Parks has emphasized the importance of sacrificing the entire sigmoid and descending colon to have a more reliable vasculature of the upper descending colon to bring down to the anus. This also gets above the bulk ofdiverticular disease in most patients. The anorectal mucosa is excised transanally after injecting an epinephrine solution submucosally, and the mucosa is excised from above the dentate line to the end of any rectal cuff if it remains, after the resection of the cancer from the abdominal dissection. The special Parks' retractor is helpful for coloanal anastomosis, which we perform without a pouch as Parks had originally described. Using 3-0 Dexon (Davis and Geck, Manati, PR), the fall thickness of the colon is sutured to the dentate line, including a portion of the internal sphincter with each suture. Alternatively, the anastomosis can be performed by a staple techniquefl ~ Two recent reports 1~,~6suggest that construction of a J-pouch for the neorectum results in a better long-term result with fewer daily bowel movements than with the standard straight coloanal anastomosis. Figures 2 through 5 show the basics of the Parks' technique for the anastomsis. Complications of pelvic sepsis, anastomotic leakage, and stricture do not appear to he more common than in anterior resection of the rectum. 21 Both Vernava Z3 and Cohen 15 have sho~aa that coloanal reconstruction can be performed after high-dose
preoperative irradiation with good results. Patient selection is very important in this procedure. Ideally, the patient's tumor should be of low to moderate histologic grade and should be mobile. Adequate sphincter tone is of great importance to a good functional result. Functional results have been good in most reported series. Parks reported normal function in 51% of 76 patients, with only a minor functional defieienc'y
- ..J-/,
i
i F i g u r e 1. Interrupted sutures of 3-0 polyglycolicacid are used for the anastomosis. Each stitch passes through the mucosa of the upper anal canal, a deep bite of the internal sphincter, and full thickness of the colon.
12
\
Herbert C. Hoover,Jr.
f'
Figure 5. The anastomosis is complete and the colon lies within a short sleeve of denuded upper internal sphincter and terminal rectum. in a n a d d i t i o n a l 39%. N o r m a l was c o n s i d e r e d full c o n t i n e n c e a n d l or 2 bowel m o v e m e n t s p e r day. T h r e e to four m o v e m e n t s p e r day w i t h full contin e n c e was c o n s i d e r e d a m i n o r deficiency. Advocates of t h e J - p o u c h r e p o r t o n e to t h r e e m o v e m e n t s p e r day in m o s t of t h e i r p a t i e n t s . A l t h o u g h all series are small w i t h g e n e r a l l y s h o r t follow-up, t h e d a t a suggest t h a t local r e c u r r e n c e a n d survival r a t e s are not adversely affected by t h e selective use o f coloanal anastomosis.
References 1. Wolmark N, Fisher B: An analysis of survival and treatment failure following abdominoperineal and sphincter-saving resection in Dukes' B and C rectal carcinoma. A report of the NSABP Clinical Trials. Ann Surg 204:480-489, 1986 2. Heald RJ, Husband EM, Ryall RDH: The mesorectum and rectal cancer surgery--Clue to pelvic recurrence? Br J Surg 68:613-616, 1982 3. Heald RJ, Ryail RDH: Recurrence and survival after total mesorectal excision for rectal cancer. Lancet 1:1479-1482, 1986
4. Mittleman A, Holyoke ED, Panahon A, et al: Prolongation of the disease-free int erval in surgically treated rectal carcinoma. N EnglJ Med 312:1465-1472, 1985 5. KrookJE, Moertel CG, Gunderson LC, et al: Effective surgical adjuvant therapy for high-risk rectal carcinoma. N EnglJ Med 324:709-715, 1991 6. Quirke P, Dixon MF, Durdey P, et al: Local recurrence of rectal adenocarcinoma due to inadequate surgical resection. Histopathological study of lateral tumour spread and surgical excision. Lancet Nov 1,996-998, 1986 7. Devereux DF, Feldman MI, McIntosh TK, et al: Efficacy of po[yglycolic acid mesh sling in keeping the small bowel in the upper abdomen after abdominal surgery: A 12-month study in baboons.J Surg Oncol 31:204-209, 1986 8. Devereux DF, Kavanah MT, Feldman MI, et al: Small bowel exclusion from the pelvis by a polyglycolic acid mesh sling. J Surg Onco126:107-112, 1984 9. Devereux DF, Thompson D, Sandhaus L, et al: Protection from radiation enteritis by an absorbable polyglycolic acid mesh sling. Surgery 101:123-129, 1987 10. Devereux DF, ChandlerJ[~, Eisenstat T, et al: Efficacy of an absorbable mesh in keeping the small bowel out of the human peMs following surgery'. Dis Colon Rectum 31 : 17-21, t 988 11. Parks AG: Per-anal anastomosis. WorldJ Surg 6:531-538, 1982 12. Nicholls RJ, Lubowski DZ, Donaldson DR: Comparison of colonic resen~oir and straight colo-anal reconstruction after rectal excision. BrJ Surg 75:318-320, 1988 13. Vernava AM, Robbins PL, Brabbee GW: Restorative resection: Coloanal anastomosis for benign and malignant disease. Dis Colon Rectum 32:690-693, 1988 14. Bernard D, Morgan S, Tasse D, et al: Preliminary results of coloanal anastomosis. Dis Colon Rectum 32:580-584, 1989 15. Cohen AM, Enker WE, Minsky BD: Proctectomy and coloanal reconstruction tbr rectal cancer. Dis Colon Rectum 33:40-43, 1990 I6. Huguet C, Harb J, Bona S: Co|oanal anastomosis after resection of low rectal cancer in the elderly. World J Surg 14:619-623, 1990 17. Dixon AR, Maxwell WA, Holmes JT: Carcinoma of the rectum: A 10-year experience. BrJ Surg 78:308-311, 1991 18. Spare F: A new surgical technique for the treatment of Hirschsprung's disease. Surgery 56:1007-1014, 1964 19. Parks AG: Transanal technique in low rectal anastomosis. Proc R Soc Med 65:925-926, 1972 20. IIluminati F, Bezzi M, Martinelli V: Simple method for stapled low colorectal or coloanal anastomosis. Dis Colon Rectum 33:351-352, 1990 21. Burke ERC, Welvaart K: Complications of stapled anastomoses in anterior resection for rectal carcinoma: Colorectal anastomosis versus coloanal anastomosis.J Surg Onco145:180183, 1990
he past decade has witnessed some revolutionary changes in the surgical management of rectal cancer, especially evident in the middle to lower rectal lesions. In this article, we focus on three significant developments: (1) the importance of mesorectal resection, (2) mobilization of the small bowel when postoperative radiation therapy is anticipated, and (3) the role ofcoloanal anastomosis.
T
Mesorectal Resection The introduction of the circular stapler has made sphincter-sparing resection of middle to lower rectal cancer considerably easier and safer for most surgeons. Fewer patients today require abdominoperiheal resection and a permanent abdominal stoma. Most studies suggest that local recurrence and survival rates have not been adversely affected by the trend toward sphincter preservation as long as an adequate resection can be accomplished. I Just what represents an acceptably wide resection remains debatable, but most would agree that a distal margin of 2 cm is adequate for most cases. A less well accepted or less widely known concept is the importance of a sharp dissection of the entire mesorectum in patients with potentially curable middle to lower rectal cancers. The British, particularly Heald et al, 2,3 have led the way in stressing the great importance of the mesorectum in rectal cancer. Their careful pathologic studies have clearly shown that lymphatic spread, although rarely beyond 1 to 2 cm intramurally, can be up to 5 cm distal in the mesorectum. The conventional blunt mobilization of the posterior rectum is discouraged for fear that tumor lymphatics or veins could be torn, or that the tumor itself could be inadvertently exposed. Sharp dissection would reasonably be expected to be less traumatic. Heald has stressed his conviction that distal spread of rectal From the Department of Surgical Oncology Research, Massachusetts GeneralHospital, Harvard Medical School, Boston. Address reprint requests to Herbert C. Hoover, Jr, MD, Surgical Ontology, Cox-l, Massachusetts GeneralHospital, Boston, ?vLet02114. Copyright 9 1993by HdB. Sounders Company 1053-4296/93 / 0301-0002505.00/0 8
cancer is often initially confined to the mesorectal tissues, and that all middle to lower rectal cancers should have complete removal of the mesorectum to the levators if the tumor does not invade the levators or sphincters and if sphincter preservation is planned (Fig 1). The conventional resection that strives for a 2-cm distal margin often "cones" down to the rectal wall distal to the lesion, leaving considerable mesorecturn. Using a combination of sharp dissection and total mesorecta] resection, Heald has reported 3 a remarkably low intrapelvic recurrence rate of 2.6%, with no staple-line recurrences in 115 patients having an anterior resection with a low anastomosis at a mean follow-up of 4.2 years. Thirty-nine patients had mural resection margins of <2.5 cms, and 69 had anastomoses below 5 cm above the anal verge. This low recurrence rate was achieved without any adjuvant therapy. With the wide variability in extent of mesorectal tissue excision among surgeons, or even within a single surgeon's practice, depending on the patient's body build and pelvic anatomy, studies evaluating results in cooperative trials with or without irradiation are impossible to interpret in terms of the importance of surgical versus radiation effect on the outcome. Based on the generally accepted fact that radiation therapy reduces the incidence of pelvic recurrences, 4,5 one would reason that a combination of wide mesorectal resection and radiation therapy would offer the best possible therapy, but this has not been adequately studied. With his data, Heald makes a legitimate argument that a proper surgical resection obviates the need for radiation therapy in all but the most advanced rectal cancers. In the United States, most rectal resections are performed by surgeons less experienced than Heald in the method of mesorectal resection, and few probably are as radical in their approach. Consequently, until more data are available from larger series at other institutions, we should not abandon our current philosophy relative to pelvic irradiation for rectal cancers that are transmural and/or spread to pelvic lymph nodes. Ideally, a prospectively randomized trial between
Seminars in Radiation Oncology, Vol3, No 1 (January), 1993:pp 8-12
SurgicalManagementofRectal Carcinoma
Line of excision includes mesorectum
",a
Site of tumour deposits in Case 6
F i g u r e 1. The suggested plane of excision is shown diagrammatically by the dashed line. (Reprinted by permission of the publishers, Butterworth-Heineman Ltd]) conventional rectal resection that leaves the distal mesorectum intact plus radiation therapy should be compared with complete mesorectal resection without radiation therapy. Such a trial would be difficult because the advocates of wide mesorectal resection with or without radiation therapy and those who perform a conventional resection and use radiation therapy are often equally sure of the merit of their approach. In the absence of such data, both a wide mesorectal resection and pelvic irradiation are probably the ideal therapy tbr patients with transmural extension or involved pelvic l?anph nodes. A related issue of considerable importance is the extent of lateral dissection of rectal cancer. By whole-mount sections of the entire operative specimen examined by transverse slicing, Quirke 6 showed spread of rectal adenocarcinoma to the lateral resection margin in 14 of 52 patients (27%). Twelve of the 14 proceeded to local pelvic recurrence. A maximally wide lateral margin is achieved by sharp dissection along the lateral pelvic side wall, with suturing of transversed vessels rather than the commonly used method of clamping and tying, which compromises the lateral margin. This applies primarily to bulky tumors of the middle to lower rectum.
Mobilization of the Small Bowel for Postoperative Radiation Therapy Radiation injury to loops of small bowel fixed in the pelvis after rectal resection is perhaps the most serious complication in patients receiving pelvic irradiation. It occurs in 5% to 15% of patients. 7Although
9
modern radiation techniques have lowered the frequency with which this complication is clinically significant, surgeons should attempt to exclude the small bowel from the pelvis in all patients that will be receiving postoperative radiation therapy. If the mesorectum and pelvic peritoneum are resected along with the rectum, closure of the pelvic peritoneum is not possible, and the small bowel will descend to fill the pelvis. It quickly becomes adherent and cannot be effectively displaced even by a steep Trendelenburg or jackknife position during radiation therapy. Preventive procedures need to be performed at the end of the rectal procedure before abdominal closure. A number of innovative procedures have been developed, such as an omentoplasty to the pelvis, suturing the urinary bladder to the pelvic presacral fascia, the use of a mammary prosthesis, and the use of absorbable mesh to separate the pelvic and abdominal cavities. Omentoplasty and/or a mesh sling currently serve well in most patients and will be described in detail. Omentoplasty
Patients who have not had procedures of the upper abdomen that included partial or full omentectomy usually have adequate omentum to fill the pelvis if mobilized adequately. The obvious advantages are its autologous nature and its rich vasculature, which can potentially aid in preventing anastomotic leaks in the pelvis or help to heal the perineal closure after an abdominoperineal resection. Pelvic dead space is filled, which theoretically minimizes the likelihood of a pelvic abscess. However, there have been no studies that have definitively shown that the entire small bowel can be kept out of the pelvic cavity with this technique. The omentum should be fully mobilized off the greater curvature of the stomach, being careful to incorporate the gastroepiploic vessels within the omental pedicle. It can then be brought down either the left or the right gutter to fill the pelvis fully or nearly so in most patients. Especially thin patients may have an inadequate omentum to satisfactorily fill the pelvic space, and an alternative procedure should be used in those patients. The omentum should be secured to the peritoneum at the pelvic inlet and all the way around to prevent any loops of small bowel from entering the pelvis and defeating the purpose of the effort. Complications should be rare, although one must be very careful with hemostasis in this well-vascularized organ. Caution should be exercised in prevent-
10
Her&rt C Hoover,Jr.
ing ureteral, vascular, or neurologic injury while securing the omentum in the peMs. Absorbable
Mesh Dam
In patients with an inadequate omentum to flit the pelvis, an alternative is to separate the abdominal and peMc cavities by suturing into place a dam of absorbable mesh. Polyglycolic acid mesh has been used successfully in several reports 8-1~in both animals and humans, and is probably the prosthetic material of choice. Its degradation properties are such that its dissolution requires 2 to 3 months, preventing the small bowel from descending into the pelvis until well after radiation therapy is completed. The technical aspects of the mesh dam or intestinal sling procedure have been well outlined by Devereaux. I~ Obviously, this method leaves a large pelvic dead space. Ideally, it could be combined with omentoplasty when the omentum is inadequate to totally fill the pelvis in an effort to eliminate as much dead space as possible. This is especially important when there is a low anastomosis in the pelvis and is of less concern after an abdominoperineal resection. In 60 patients, Devereux reported I~ a mean total dose of pelvic irradiation of 5,500 rad. At 28 months of mean follow-up, there were no cases of radiation enteritis, small bowel obstruction, fistula or intraabdominal sepsis. Prolonged ileus was the only complication noted. Four patients reexplored 6 to 12 months postoperatively had no evidence of mesh present and no mesh-related adhesions such as a "cocoon" surrounding the small bowel. My limited experience has shown similar findings. This technique can be enthusiastically recommended for use in selected patients
)
where high-dose postoperative radiation therapy is definitely indicated.
Role of Coloanal A n a s t o m o s e s in Rectal Cancers The improvements in the circular staplers now allow a safe anastomosis tovery low levels in the rectum or even to the anus itself. Experience has shown that anal continence depends on maintenance of the anal sphincter itself, but does not require any rectal reservoir. Most data suggest that a 2-cm distal mural margin is adequate in the resection of rectal cancers. Therefore, selective rectal cancers that are at least 2 cm from the anal verge can be resected with an adequate margin and continuity and continence restored by means ofa coloanal anastomosis, achieved either by a staple or hand-sewn technique. Theoretically, with today's approaches, abdominoperineal resection can be limited to patients with invasion of the pelvic floor or anal sphincter. Numerous studies ll-17 now suggest that local control and cure are not compromised by these sphincter-sparing approaches in patients with tumors that are not locally extensive. The concept for coloanal anastomosis was developed by Soave Is in 1964 when he described a rectal mucosectomy combined with an endorectal coloanal sleeve anastomosis for the treatment of Hirschsprung's disease. In 1972, Parks m used a similar procedure for benign rectal conditions in the adult and reported its use for malignancies in 1982.u Parks' technique has been altered by various surgeons but still serves as the basis for this approach.
-~
,
Figure 2. (Left) A solution of adrenaline in normal saline (l:300,000) is injected into the submucosa of the rectal stump. (Right) The columnar mucosa is dissected off the submucosa above the dentate line.
SurgicalManagementofRectalCamnoma
11
F i g u r e 3. (Left) The circular muscle of the upper anal canal and rectal stump can be seen. (Right) The retractor is repositioned to expose the entire circumference in about three maneuvers.
Important technical details include division of the inferior mesenteric vessels at their origin to allow an adequate length of mesocolon for a tension-free anastomosis. Parks has emphasized the importance of sacrificing the entire sigmoid and descending colon to have a more reliable vasculature of the upper descending colon to bring down to the anus. This also gets above the bulk ofdiverticular disease in most patients. The anorectal mucosa is excised transanally after injecting an epinephrine solution submucosally, and the mucosa is excised from above the dentate line to the end of any rectal cuff if it remains, after the resection of the cancer from the abdominal dissection. The special Parks' retractor is helpful for coloanal anastomosis, which we perform without a pouch as Parks had originally described. Using 3-0 Dexon (Davis and Geck, Manati, PR), the fall thickness of the colon is sutured to the dentate line, including a portion of the internal sphincter with each suture. Alternatively, the anastomosis can be performed by a staple techniquefl ~ Two recent reports 1~,~6suggest that construction of a J-pouch for the neorectum results in a better long-term result with fewer daily bowel movements than with the standard straight coloanal anastomosis. Figures 2 through 5 show the basics of the Parks' technique for the anastomsis. Complications of pelvic sepsis, anastomotic leakage, and stricture do not appear to he more common than in anterior resection of the rectum. 21 Both Vernava Z3 and Cohen 15 have sho~aa that coloanal reconstruction can be performed after high-dose
preoperative irradiation with good results. Patient selection is very important in this procedure. Ideally, the patient's tumor should be of low to moderate histologic grade and should be mobile. Adequate sphincter tone is of great importance to a good functional result. Functional results have been good in most reported series. Parks reported normal function in 51% of 76 patients, with only a minor functional defieienc'y
- ..J-/,
i
i F i g u r e 1. Interrupted sutures of 3-0 polyglycolicacid are used for the anastomosis. Each stitch passes through the mucosa of the upper anal canal, a deep bite of the internal sphincter, and full thickness of the colon.
12
\
Herbert C. Hoover,Jr.
f'
Figure 5. The anastomosis is complete and the colon lies within a short sleeve of denuded upper internal sphincter and terminal rectum. in a n a d d i t i o n a l 39%. N o r m a l was c o n s i d e r e d full c o n t i n e n c e a n d l or 2 bowel m o v e m e n t s p e r day. T h r e e to four m o v e m e n t s p e r day w i t h full contin e n c e was c o n s i d e r e d a m i n o r deficiency. Advocates of t h e J - p o u c h r e p o r t o n e to t h r e e m o v e m e n t s p e r day in m o s t of t h e i r p a t i e n t s . A l t h o u g h all series are small w i t h g e n e r a l l y s h o r t follow-up, t h e d a t a suggest t h a t local r e c u r r e n c e a n d survival r a t e s are not adversely affected by t h e selective use o f coloanal anastomosis.
References 1. Wolmark N, Fisher B: An analysis of survival and treatment failure following abdominoperineal and sphincter-saving resection in Dukes' B and C rectal carcinoma. A report of the NSABP Clinical Trials. Ann Surg 204:480-489, 1986 2. Heald RJ, Husband EM, Ryall RDH: The mesorectum and rectal cancer surgery--Clue to pelvic recurrence? Br J Surg 68:613-616, 1982 3. Heald RJ, Ryail RDH: Recurrence and survival after total mesorectal excision for rectal cancer. Lancet 1:1479-1482, 1986
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