- Email: [email protected]
Advances in the Treatment of Oligometastatic Disease:
ARTICLE IN PRESS
Perspective
Advances in the Treatment of Oligometastatic Disease: What the Radiologist Needs to Know to Guide Patient Management Steven P. Rowe, MD, PhD, Hazem Hawasli, MD, Elliot K. Fishman, MD, Pamela T. Johnson, MD Rationale and Objectives: An ever-expanding body of biological, genetic, and clinical evidence has brought to light the presence of the oligometastatic state of cancer, which is considered between localized disease and widespread metastases. Indeed, in some patients with oligometastatic disease, curative therapy is possible. Conclusions: For select cancer histologies, aggressive focal therapy of oligometastatic lesions is already the clinical standard of care (i.e. colorectal cancer and sarcomas), while for other tumor types the evidence is still emerging (i.e. prostate, breast, etc.). It is increasingly important, therefore, for the radiologist interpreting oncology patients’ staging or restaging examinations to be aware of those diseases for which targeted therapy of oligometastases may be undertaken to effectively guide such management. The improved imaging resolution provided by technological advances promise to aid in the detection of subtle sites of disease to ensure the identification of patients with oligometastases amenable to targeted treatment. Key Words: Cancer imaging; Oligometastatic disease. © 2015 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
INTRODUCTION
I
n a landmark paper in 1995, Hellman and Weichselbaum (1) postulated the oligometastatic state of oncologic disease, in which patients may harbor a limited number of metastatic lesions. This state was viewed as existing on a continuum between localized and diffuse metastatic diseases, with oligometastic patients potentially receiving improved systemic control or even cure of their disease from treatment directed at these discrete metastatic foci. Indeed, there is increasing evidence on the molecular and genetic levels that oligometastatic disease is a distinct entity from diffusely metastatic disease, with the metastatic cells in oligometastases displaying a phenotype that lacks some of the elements necessary to bring about widespread metastases (2). This recognition results in a profoundly important change from the dogma that a small number of identifiable metastatic lesions necessarily connote widespread systemic disease and a stage of cancer only amenable to systemic chemotherapy. In light of this shifting perception about the nature of metastatic cancer, for those patients in whom there are a small number
of discretely identifiable lesions, it is becoming increasingly incumbent upon the interpreting radiologist to delineate each of those lesions. An approach in which only an index lesion is specifically commented upon when a small number of other lesions are present may be inadequate in certain clinical contexts. Indeed, the radiologist should be cognizant of the need to guide treatment in cases of oligometastatic disease, which can include a variety of local therapies such as radiation, surgery, or cryotherapy. Although a number of definitions of oligometastatic disease have been suggested, and refinement of the concept of oligometastasis may eventually arrive at different definitions for different diseases, most commonly five or fewer distinct lesions are considered oligometastases (3). This opinion piece discusses the malignancies in which aggressive treatment of oligometastic disease is already widely clinically accepted, as well as those in which there is emerging evidence that such treatment may be beneficial. We also refer the reader to an excellent and comprehensive review by Reyes and Pienta (3) that discusses the biology of oligometastsic disease and the current clinical trials ongoing within this realm.
Acad Radiol 2015; ■:■■–■■ From The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287. Received October 22, 2015; revised October 22, 2015; accepted November 2, 2015. Address correspondence to: P.T.J. e-mail: [email protected] © 2015 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.acra.2015.11.006
COLORECTAL CANCER Oligometastatic colorectal cancer involving the liver represents a prototype for the aggressive treatment of a small number of metastatic lesions, with liver resection taking place before, after, or at the time of resection of the primary 1
ROWE ET AL
(4). Thermal and radiofrequency ablation can also be used in the treatment of oligometastatic disease to the liver. Treatment of oligometastatic colorectal cancer to the liver can be curative in some patients (5). In any case of colorectal cancer staging or restaging with cross-sectional imaging, it is of utmost importance to examine the liver for any suspicious lesion(s) and to accurately identify their locations within the liver, unless such lesions are widespread or diffuse. After the liver, the second most common site of colorectal cancer metastases is the lungs. Oligometastatic disease involving the lungs can also be targeted for an attempt at cure (6). Thus, a careful examination for, and delineation of, lung nodules is essential when patients with colorectal cancer are imaged. Interestingly, there are data that suggest that selected patients with colorectal oligometastases to both the liver and the lungs may benefit from aggressive therapy to the involved sites of both organ systems (7)—thus, radiologic findings of disease in both the lungs and the liver may not preclude curative surgery and should be carefully sought.
Academic Radiology, Vol ■, No ■, ■■ 2015
an indeterminate renal mass for staging, as well as patients with a history of RCC presenting for restaging.
SARCOMAS Another classic family of malignancies for which oligometastaticfocused therapy is well established is the sarcomas. By far, the most common site of metastases from sarcomas is the lungs, and in any patient with this diagnosis, it is incumbent upon the radiologist to carefully search for the presence of all pulmonary nodules. In many other malignancies, a new small lung nodule does not carry the same significance as that in a patient with sarcoma. Current treatment modalities include wedge resection or lobectomy, stereotactic radiation, or percutaneous ablation. Recent data suggest that there is a survival benefit from local treatment of oligometastases in both soft tissue and bone sarcomas and that patients continue to benefit even after repeated interventions to treat successive rounds of oligometastases (16). Nonetheless, optimal management is guided by identification of all lung metastases before surgery.
PROSTATE CANCER Prostate cancer remains the second most commonly diagnosed malignancy and second most common cause of cancer death in men in the United States (8). Given how common this disease is and the relatively indolent course of many prostate cancers, it is perhaps not surprising that there is growing literature to support oligometastatic-directed therapy such as stereotactic radiotherapy and salvage lymphadenectomy (9–11). Common sites of spread of metastatic prostate cancer include the pelvic and retroperitoneal lymph nodes as well as skeleton, and the attention of the radiologist should be focused on these structures when evaluating a patient for staging or restaging. Prostate cancer also represents a disease for which improvements in imaging technology could lead to more appropriately directed therapy given the proliferation of new nuclear imaging radiotracers that are able to identify such findings as small lymph node metastases (12–14). As local therapy for prostate cancer oligometastases gains acceptance, guidance of such therapy by these new molecular imaging agents is likely to be of increasing importance. RENAL CELL CARCINOMA (RCC) There is a great deal of experience in the realm of oligometastatic RCC. Although aggressive treatment of RCC oligometastases remains controversial, a recent systematic review suggested that patients who received metastasectomy or radiotherapy had improved survival in comparison to those patients who did not receive local therapy (15). However, large prospective trials to confirm this benefit are lacking. Common sites of metastases from RCC include the adrenal glands, lung, skeleton, and lymph nodes (retroperitoneal, mediastinal, and hilar), and these sites deserve special attention from the interpreting radiologist in patients presenting with 2
LUNG CANCER The second most common cause of cancer in both men and women and the leading cause of cancer-related death (8), nonsmall cell lung cancer (NSCLC) is often metastatic at presentation (17). As a result, there has been extensive study of oligometastatic NSCLC, with current treatment options including both surgical resection and radiation therapy. Oligometastatic NSCLC patients effectively treated at all sites of disease have demonstrated improved survival (18). Careful scrutiny of imaging studies for lung and lymph node metastases in these patients is critical to identify those patients who might benefit from aggressive treatment of limited metastatic disease. Metastases to the adrenal glands should also be sought, as adrenal metastasectomy can lead to long-term survival in some patients (19).
OTHER CANCER TYPES Only limited information is available in regard to treatment of oligometastases in breast cancer, although a number of retrospective studies have suggested a benefit from aggressive therapy with a definable number of metastatic lesions (20,21). Similarly, the evidence for aggressive treatment of oligometastases in melanoma is scant, but a large study did conclude that attempted curative resection of a small number of metastatic lesions could benefit some patients (22). Additionally, at least 42 current clinical trials are underway to further assess the utility of aggressive therapy of oligometastatic disease (3), some of which will address the tumor types described above and some of which will expand the concept of beneficial/curative therapy for oligometastases to new tumor histologies.
Academic Radiology, Vol ■, No ■, ■■ 2015
ADVANCES IN TREATING OLIGOMETASTATIC DISEASE
CONCLUSION
7. Neeff H, Hörth W, Makowiec F, et al. Outcome after resection of hepatic and pulmonary metastases of colorectal cancer. J Gastrointest Surg 2009; 13:1813–1820. 8. Siegel RL, Miller KD, Jemal A. Cancer statistics, 2015. CA Cancer J Clin 2015; 65:5–29. 9. Decaestecker K, De Meerleer G, Ameye F, et al. Surveillance or metastasisdirected Therapy for OligoMetastatic Prostate cancer recurrence (STOMP): study protocol for a randomized phase II trial. BMC Cancer 2014; 14:671. 10. Aoun F, Peltier A, Velthoven R. A comprehensive review of contemporary role of local treatment of the primary tumor and/or metastases in metastatic prostate cancer. Biomed Res Int 2014; 2014:501213. 11. Conde Moreno AJ, Ferrer Albiach C, Muelas Soria R, et al. Oligometastases in prostate cancer: restaging stage IV cancers and new radiotherapy options. Radiat Oncol 2014; 9:258. 12. Cho SY, Gage KL, Mease RC, et al. Biodistribution, tumor detection, and radiation dosimetry of 18F-DCFBC, a low-molecular-weight inhibitor of prostate-specific membrane antigen, in patients with metastatic prostate cancer. J Nucl Med 2012; 53:1883–1891. 13. Szabo Z, Mena E, Rowe SP, et al. Initial evaluation of [18F]DCFPyL for prostate-specific membrane antigen (PSMA)-targeted PET imaging of prostate cancer. Mol Imaging Biol 2015; 17:565–574. 14. Dietlein M, Kobe C, Kuhnert G, et al. Comparison of [18F]DCFPyL and [68Ga]Ga-PSMA-HBED-CC for PSMA-PET imaging in patients with relapsed prostate cancer. Mol Imaging Biol 2015; 17:575–584. 15. Dabestani S, Marconi L, Hofmann F, et al. Local treatments for metastases of renal cell carcinoma: a systematic review. Lancet Oncol 2014; 15:e549–e561. 16. Falk AT, Moureau-Zabotto L, Ouali M, et al. Effect on survival of local ablative treatment of metastases from sarcomas: a study of the French sarcoma group. Clin Oncol (R Coll Radiol) 2015; 27:48–55. 17. Ashworth A, Rodrigues G, Boldt G, et al. Is there an oligometastatic state in non-small cell lung cancer? A systematic review of the literature. Lung Cancer 2013; 82:197–203. 18. Salama JK, Schild SE. Radiation therapy for oligometastatic non-small cell lung cancer. Cancer Metastasis Reg 2015; 34:183–193. 19. Porte H, Siat J, Guibert B, et al. Resection of adrenal metastases from non-small cell lung cancer: a multicenter study. Ann Thorac Surg 2001; 71:981–985. 20. Pagani O, Senkus E, Wood W, et al. International guidelines for management of metastatic breast cancer: can metastatic breast cancer be cured? J Natl Cancer Inst 2010; 102:456–463. 21. Di Lascio S, Pagani O. Oligometastatic breast cancer: a shift from palliative to potentially curative treatment? Breast Care (Basel) 2014; 9:7– 14. 22. Essner R, Lee JH, Wanek LA, et al. Contemporary surgical treatment of advanced stage melanoma. Arch Surg 2004; 139:961–966.
In the context of increasing biological and clinical evidence that oligometastatic cancer is a truly separate entity from either localized disease or widely disseminated metastatic disease, the role of the radiologist has evolved from identifying any site of metastatic disease to carefully delineating all sites of disease, particularly in the setting of less than five metastases. With ever-improving spatial resolution and protocol development in computed tomography and magnetic resonance imaging and the promise of highly specific and sensitive molecular imaging with nuclear medicine and magnetic resonance imaging, the ability of radiologists to confidently identify all of sites of metastatic disease in an oncology patient will only increase. As such, some of the impetus for exploring aggressive and potentially curative treatment in patients with oligometastases can come from improvements in imaging technology and techniques. Thus, radiologists should not only understand the implications of the new paradigm of oligometastatic disease for how they interpret studies, but they should also actively engage in the research necessary to optimize the selection of patients for aggressive therapy of oligometastases.
REFERENCES 1. Hellman S, Weichselbaum RR. Oligometastases. J Clin Oncol 1995; 13:8– 10. 2. Corbin KS, Hellman S, Weichselbaum RR. Extracranial oligometastases: a subset of metastases curable with stereotactic radiotherapy. J Clin Oncol 2013; 31:1384–1390. 3. Reyes DK, Pienta KJ. The biology and treatment of oligometastatic cancer. Oncotarget 2015; 6:8491–8524. 4. Kelly ME, Spolverato G, Lê GN, et al. Synchronous liver metastasis: a network meta-analysis review comparing classical, combined, and liverfirst surgical strategies. J Surg Oncol 2015; 111:341–351. 5. Tomlinson JS, Jarnagin ER, DeMatteo RP, et al. Actual 10-year survival after resection of colorectal liver metastases defines cure. J Clin Oncol 2007; 25:4575–4580. 6. Salah S, Watanabe K, Welter S, et al. Colorectal cancer pulmonary metastases: pooled analysis and construction of a clinical lung metastasectomy prognostic model. Ann Oncol 2012; 23:2649–2655.
3
Perspective
Advances in the Treatment of Oligometastatic Disease: What the Radiologist Needs to Know to Guide Patient Management Steven P. Rowe, MD, PhD, Hazem Hawasli, MD, Elliot K. Fishman, MD, Pamela T. Johnson, MD Rationale and Objectives: An ever-expanding body of biological, genetic, and clinical evidence has brought to light the presence of the oligometastatic state of cancer, which is considered between localized disease and widespread metastases. Indeed, in some patients with oligometastatic disease, curative therapy is possible. Conclusions: For select cancer histologies, aggressive focal therapy of oligometastatic lesions is already the clinical standard of care (i.e. colorectal cancer and sarcomas), while for other tumor types the evidence is still emerging (i.e. prostate, breast, etc.). It is increasingly important, therefore, for the radiologist interpreting oncology patients’ staging or restaging examinations to be aware of those diseases for which targeted therapy of oligometastases may be undertaken to effectively guide such management. The improved imaging resolution provided by technological advances promise to aid in the detection of subtle sites of disease to ensure the identification of patients with oligometastases amenable to targeted treatment. Key Words: Cancer imaging; Oligometastatic disease. © 2015 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
INTRODUCTION
I
n a landmark paper in 1995, Hellman and Weichselbaum (1) postulated the oligometastatic state of oncologic disease, in which patients may harbor a limited number of metastatic lesions. This state was viewed as existing on a continuum between localized and diffuse metastatic diseases, with oligometastic patients potentially receiving improved systemic control or even cure of their disease from treatment directed at these discrete metastatic foci. Indeed, there is increasing evidence on the molecular and genetic levels that oligometastatic disease is a distinct entity from diffusely metastatic disease, with the metastatic cells in oligometastases displaying a phenotype that lacks some of the elements necessary to bring about widespread metastases (2). This recognition results in a profoundly important change from the dogma that a small number of identifiable metastatic lesions necessarily connote widespread systemic disease and a stage of cancer only amenable to systemic chemotherapy. In light of this shifting perception about the nature of metastatic cancer, for those patients in whom there are a small number
of discretely identifiable lesions, it is becoming increasingly incumbent upon the interpreting radiologist to delineate each of those lesions. An approach in which only an index lesion is specifically commented upon when a small number of other lesions are present may be inadequate in certain clinical contexts. Indeed, the radiologist should be cognizant of the need to guide treatment in cases of oligometastatic disease, which can include a variety of local therapies such as radiation, surgery, or cryotherapy. Although a number of definitions of oligometastatic disease have been suggested, and refinement of the concept of oligometastasis may eventually arrive at different definitions for different diseases, most commonly five or fewer distinct lesions are considered oligometastases (3). This opinion piece discusses the malignancies in which aggressive treatment of oligometastic disease is already widely clinically accepted, as well as those in which there is emerging evidence that such treatment may be beneficial. We also refer the reader to an excellent and comprehensive review by Reyes and Pienta (3) that discusses the biology of oligometastsic disease and the current clinical trials ongoing within this realm.
Acad Radiol 2015; ■:■■–■■ From The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287. Received October 22, 2015; revised October 22, 2015; accepted November 2, 2015. Address correspondence to: P.T.J. e-mail: [email protected] © 2015 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.acra.2015.11.006
COLORECTAL CANCER Oligometastatic colorectal cancer involving the liver represents a prototype for the aggressive treatment of a small number of metastatic lesions, with liver resection taking place before, after, or at the time of resection of the primary 1
ROWE ET AL
(4). Thermal and radiofrequency ablation can also be used in the treatment of oligometastatic disease to the liver. Treatment of oligometastatic colorectal cancer to the liver can be curative in some patients (5). In any case of colorectal cancer staging or restaging with cross-sectional imaging, it is of utmost importance to examine the liver for any suspicious lesion(s) and to accurately identify their locations within the liver, unless such lesions are widespread or diffuse. After the liver, the second most common site of colorectal cancer metastases is the lungs. Oligometastatic disease involving the lungs can also be targeted for an attempt at cure (6). Thus, a careful examination for, and delineation of, lung nodules is essential when patients with colorectal cancer are imaged. Interestingly, there are data that suggest that selected patients with colorectal oligometastases to both the liver and the lungs may benefit from aggressive therapy to the involved sites of both organ systems (7)—thus, radiologic findings of disease in both the lungs and the liver may not preclude curative surgery and should be carefully sought.
Academic Radiology, Vol ■, No ■, ■■ 2015
an indeterminate renal mass for staging, as well as patients with a history of RCC presenting for restaging.
SARCOMAS Another classic family of malignancies for which oligometastaticfocused therapy is well established is the sarcomas. By far, the most common site of metastases from sarcomas is the lungs, and in any patient with this diagnosis, it is incumbent upon the radiologist to carefully search for the presence of all pulmonary nodules. In many other malignancies, a new small lung nodule does not carry the same significance as that in a patient with sarcoma. Current treatment modalities include wedge resection or lobectomy, stereotactic radiation, or percutaneous ablation. Recent data suggest that there is a survival benefit from local treatment of oligometastases in both soft tissue and bone sarcomas and that patients continue to benefit even after repeated interventions to treat successive rounds of oligometastases (16). Nonetheless, optimal management is guided by identification of all lung metastases before surgery.
PROSTATE CANCER Prostate cancer remains the second most commonly diagnosed malignancy and second most common cause of cancer death in men in the United States (8). Given how common this disease is and the relatively indolent course of many prostate cancers, it is perhaps not surprising that there is growing literature to support oligometastatic-directed therapy such as stereotactic radiotherapy and salvage lymphadenectomy (9–11). Common sites of spread of metastatic prostate cancer include the pelvic and retroperitoneal lymph nodes as well as skeleton, and the attention of the radiologist should be focused on these structures when evaluating a patient for staging or restaging. Prostate cancer also represents a disease for which improvements in imaging technology could lead to more appropriately directed therapy given the proliferation of new nuclear imaging radiotracers that are able to identify such findings as small lymph node metastases (12–14). As local therapy for prostate cancer oligometastases gains acceptance, guidance of such therapy by these new molecular imaging agents is likely to be of increasing importance. RENAL CELL CARCINOMA (RCC) There is a great deal of experience in the realm of oligometastatic RCC. Although aggressive treatment of RCC oligometastases remains controversial, a recent systematic review suggested that patients who received metastasectomy or radiotherapy had improved survival in comparison to those patients who did not receive local therapy (15). However, large prospective trials to confirm this benefit are lacking. Common sites of metastases from RCC include the adrenal glands, lung, skeleton, and lymph nodes (retroperitoneal, mediastinal, and hilar), and these sites deserve special attention from the interpreting radiologist in patients presenting with 2
LUNG CANCER The second most common cause of cancer in both men and women and the leading cause of cancer-related death (8), nonsmall cell lung cancer (NSCLC) is often metastatic at presentation (17). As a result, there has been extensive study of oligometastatic NSCLC, with current treatment options including both surgical resection and radiation therapy. Oligometastatic NSCLC patients effectively treated at all sites of disease have demonstrated improved survival (18). Careful scrutiny of imaging studies for lung and lymph node metastases in these patients is critical to identify those patients who might benefit from aggressive treatment of limited metastatic disease. Metastases to the adrenal glands should also be sought, as adrenal metastasectomy can lead to long-term survival in some patients (19).
OTHER CANCER TYPES Only limited information is available in regard to treatment of oligometastases in breast cancer, although a number of retrospective studies have suggested a benefit from aggressive therapy with a definable number of metastatic lesions (20,21). Similarly, the evidence for aggressive treatment of oligometastases in melanoma is scant, but a large study did conclude that attempted curative resection of a small number of metastatic lesions could benefit some patients (22). Additionally, at least 42 current clinical trials are underway to further assess the utility of aggressive therapy of oligometastatic disease (3), some of which will address the tumor types described above and some of which will expand the concept of beneficial/curative therapy for oligometastases to new tumor histologies.
Academic Radiology, Vol ■, No ■, ■■ 2015
ADVANCES IN TREATING OLIGOMETASTATIC DISEASE
CONCLUSION
7. Neeff H, Hörth W, Makowiec F, et al. Outcome after resection of hepatic and pulmonary metastases of colorectal cancer. J Gastrointest Surg 2009; 13:1813–1820. 8. Siegel RL, Miller KD, Jemal A. Cancer statistics, 2015. CA Cancer J Clin 2015; 65:5–29. 9. Decaestecker K, De Meerleer G, Ameye F, et al. Surveillance or metastasisdirected Therapy for OligoMetastatic Prostate cancer recurrence (STOMP): study protocol for a randomized phase II trial. BMC Cancer 2014; 14:671. 10. Aoun F, Peltier A, Velthoven R. A comprehensive review of contemporary role of local treatment of the primary tumor and/or metastases in metastatic prostate cancer. Biomed Res Int 2014; 2014:501213. 11. Conde Moreno AJ, Ferrer Albiach C, Muelas Soria R, et al. Oligometastases in prostate cancer: restaging stage IV cancers and new radiotherapy options. Radiat Oncol 2014; 9:258. 12. Cho SY, Gage KL, Mease RC, et al. Biodistribution, tumor detection, and radiation dosimetry of 18F-DCFBC, a low-molecular-weight inhibitor of prostate-specific membrane antigen, in patients with metastatic prostate cancer. J Nucl Med 2012; 53:1883–1891. 13. Szabo Z, Mena E, Rowe SP, et al. Initial evaluation of [18F]DCFPyL for prostate-specific membrane antigen (PSMA)-targeted PET imaging of prostate cancer. Mol Imaging Biol 2015; 17:565–574. 14. Dietlein M, Kobe C, Kuhnert G, et al. Comparison of [18F]DCFPyL and [68Ga]Ga-PSMA-HBED-CC for PSMA-PET imaging in patients with relapsed prostate cancer. Mol Imaging Biol 2015; 17:575–584. 15. Dabestani S, Marconi L, Hofmann F, et al. Local treatments for metastases of renal cell carcinoma: a systematic review. Lancet Oncol 2014; 15:e549–e561. 16. Falk AT, Moureau-Zabotto L, Ouali M, et al. Effect on survival of local ablative treatment of metastases from sarcomas: a study of the French sarcoma group. Clin Oncol (R Coll Radiol) 2015; 27:48–55. 17. Ashworth A, Rodrigues G, Boldt G, et al. Is there an oligometastatic state in non-small cell lung cancer? A systematic review of the literature. Lung Cancer 2013; 82:197–203. 18. Salama JK, Schild SE. Radiation therapy for oligometastatic non-small cell lung cancer. Cancer Metastasis Reg 2015; 34:183–193. 19. Porte H, Siat J, Guibert B, et al. Resection of adrenal metastases from non-small cell lung cancer: a multicenter study. Ann Thorac Surg 2001; 71:981–985. 20. Pagani O, Senkus E, Wood W, et al. International guidelines for management of metastatic breast cancer: can metastatic breast cancer be cured? J Natl Cancer Inst 2010; 102:456–463. 21. Di Lascio S, Pagani O. Oligometastatic breast cancer: a shift from palliative to potentially curative treatment? Breast Care (Basel) 2014; 9:7– 14. 22. Essner R, Lee JH, Wanek LA, et al. Contemporary surgical treatment of advanced stage melanoma. Arch Surg 2004; 139:961–966.
In the context of increasing biological and clinical evidence that oligometastatic cancer is a truly separate entity from either localized disease or widely disseminated metastatic disease, the role of the radiologist has evolved from identifying any site of metastatic disease to carefully delineating all sites of disease, particularly in the setting of less than five metastases. With ever-improving spatial resolution and protocol development in computed tomography and magnetic resonance imaging and the promise of highly specific and sensitive molecular imaging with nuclear medicine and magnetic resonance imaging, the ability of radiologists to confidently identify all of sites of metastatic disease in an oncology patient will only increase. As such, some of the impetus for exploring aggressive and potentially curative treatment in patients with oligometastases can come from improvements in imaging technology and techniques. Thus, radiologists should not only understand the implications of the new paradigm of oligometastatic disease for how they interpret studies, but they should also actively engage in the research necessary to optimize the selection of patients for aggressive therapy of oligometastases.
REFERENCES 1. Hellman S, Weichselbaum RR. Oligometastases. J Clin Oncol 1995; 13:8– 10. 2. Corbin KS, Hellman S, Weichselbaum RR. Extracranial oligometastases: a subset of metastases curable with stereotactic radiotherapy. J Clin Oncol 2013; 31:1384–1390. 3. Reyes DK, Pienta KJ. The biology and treatment of oligometastatic cancer. Oncotarget 2015; 6:8491–8524. 4. Kelly ME, Spolverato G, Lê GN, et al. Synchronous liver metastasis: a network meta-analysis review comparing classical, combined, and liverfirst surgical strategies. J Surg Oncol 2015; 111:341–351. 5. Tomlinson JS, Jarnagin ER, DeMatteo RP, et al. Actual 10-year survival after resection of colorectal liver metastases defines cure. J Clin Oncol 2007; 25:4575–4580. 6. Salah S, Watanabe K, Welter S, et al. Colorectal cancer pulmonary metastases: pooled analysis and construction of a clinical lung metastasectomy prognostic model. Ann Oncol 2012; 23:2649–2655.
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