Case 18-2004: A 61-Year-Old Man with Rectal Bleeding
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《新英格兰医药杂志》
To the Editor: Case 18-2004, discussed by Shellito et al. (June 10 issue),1 concerns the management of rectal cancer and contains the recommendation that adequate pathological examination of resection specimens requires retrieval of no fewer than 15 mesorectal lymph nodes. In my experience, specimens from this region in patients who were not given preoperative treatment are rarely likely to contain such a high number of lymph nodes, and specimens from those given the treatment are even less so. The number of lymph nodes varies throughout the length of the colorectum — and even from patient to patient — with the rectum, in particular, being a node-poor zone. Neoadjuvant therapy worsens the node harvest, as it appears to ablate or reduce in size many normal lymph nodes. Retrieval of four or five nodes after such treatment is more realistic, with some specimens, despite meticulous examination, yielding none. Use of fat-clearing techniques may help, but I wonder what the likelihood is of nodes thus found having metastases. Surgeons and oncologists-in-training should attempt at least once to search for perirectal lymph nodes from these specimens to appreciate just how difficult the task can be.
Andrew Mitchell, M.D.
H?pital Maisonneuve–Rosemont
Montreal, QC H1T 2M4, Canada
amitchell.hmr@ssss.gouv.qc.ca
References
Case Records of the Massachusetts General Hospital (Case 18-2004). N Engl J Med 2004;350:2500-2509.
To the Editor: In an otherwise superb review of new advances in the management of rectal cancer, the discussants of Case 18-2004 omit information on the patient's family history and the tumor microsatellite-instability status. Family history is important because hereditary nonpolyposis colorectal cancer has a nonspecific phenotype and familial aggregation is often the only clue to this diagnosis.1 In this case, however, hereditary nonpolyposis colorectal cancer can already be suspected on the basis of the occurrence of synchronous colorectal cancers. This feature is a criterion for tumor microsatellite-instability testing in the recently revised Bethesda Guidelines for identifying persons at risk for hereditary nonpolyposis colorectal cancer.2 In one study, this criterion was 96 percent sensitive for the prediction of high-frequency microsatellite instability,3 which is itself associated with a substantial risk of the germ-line mutation for hereditary nonpolyposis colorectal cancer. The management of rectal cancer in a patient such as the one in this case should therefore include tumor microsatellite-instability testing and, if the results are positive, counseling for genetic testing for hereditary nonpolyposis colorectal cancer.
Beno?t Panzini, M.D.
Centre Hospitalier Universitaire de Montréal
Montreal, QC H2L 4M1, Canada
benoit.panzini.chum@ssss.gouv.qc.ca
References
Lynch HT, de la Chapelle A. Hereditary colorectal cancer. N Engl J Med 2003;348:919-932.
Umar A, Boland CR, Terdiman JP, et al. Revised Bethesda Guidelines for hereditary nonpolyposis colorectal cancer (Lynch syndrome) and microsatellite instability. J Natl Cancer Inst 2004;96:261-268.
Terdiman JP, Gum JR Jr, Conrad PG, et al. Efficient detection of hereditary nonpolyposis colorectal cancer gene carriers by screening for tumor microsatellite instability before germline genetic testing. Gastroenterology 2001;120:21-30.
The authors reply: We agree with Dr. Mitchell that there is much variation in the number of lymph nodes that can be retrieved and also variability that is based on the meticulousness of the pathologist.
Dr. Panzini is right to call attention to the importance of genetic syndromes in colorectal cancer. We did not emphasize it in the discussion because the assessment of a genetic component did not influence how we managed this patient's cancer. His family history was negative for colorectal neoplasms, however. We have no standard institutional policy with respect to the determination of microsatellite-instability status in colorectal cancers. The pathologist may select cases for microsatellite-instability determination on the basis of clinicopathological characteristics, which may include a family history of colorectal cancer, a right-sided tumor in a patient younger than 50 years of age, synchronous or metachronous colorectal cancers, or histologic findings suggestive of a tumor with microsatellite instability. Nevertheless, some clinicians worry about the long-term implications for the patient and family members when genetic tests are performed.
Paul C. Shellito, M.D.
Aaron P. Caplan, M.D.
Massachusetts General Hospital
Boston, MA 02114
Andrew Mitchell, M.D.
H?pital Maisonneuve–Rosemont
Montreal, QC H1T 2M4, Canada
amitchell.hmr@ssss.gouv.qc.ca
References
Case Records of the Massachusetts General Hospital (Case 18-2004). N Engl J Med 2004;350:2500-2509.
To the Editor: In an otherwise superb review of new advances in the management of rectal cancer, the discussants of Case 18-2004 omit information on the patient's family history and the tumor microsatellite-instability status. Family history is important because hereditary nonpolyposis colorectal cancer has a nonspecific phenotype and familial aggregation is often the only clue to this diagnosis.1 In this case, however, hereditary nonpolyposis colorectal cancer can already be suspected on the basis of the occurrence of synchronous colorectal cancers. This feature is a criterion for tumor microsatellite-instability testing in the recently revised Bethesda Guidelines for identifying persons at risk for hereditary nonpolyposis colorectal cancer.2 In one study, this criterion was 96 percent sensitive for the prediction of high-frequency microsatellite instability,3 which is itself associated with a substantial risk of the germ-line mutation for hereditary nonpolyposis colorectal cancer. The management of rectal cancer in a patient such as the one in this case should therefore include tumor microsatellite-instability testing and, if the results are positive, counseling for genetic testing for hereditary nonpolyposis colorectal cancer.
Beno?t Panzini, M.D.
Centre Hospitalier Universitaire de Montréal
Montreal, QC H2L 4M1, Canada
benoit.panzini.chum@ssss.gouv.qc.ca
References
Lynch HT, de la Chapelle A. Hereditary colorectal cancer. N Engl J Med 2003;348:919-932.
Umar A, Boland CR, Terdiman JP, et al. Revised Bethesda Guidelines for hereditary nonpolyposis colorectal cancer (Lynch syndrome) and microsatellite instability. J Natl Cancer Inst 2004;96:261-268.
Terdiman JP, Gum JR Jr, Conrad PG, et al. Efficient detection of hereditary nonpolyposis colorectal cancer gene carriers by screening for tumor microsatellite instability before germline genetic testing. Gastroenterology 2001;120:21-30.
The authors reply: We agree with Dr. Mitchell that there is much variation in the number of lymph nodes that can be retrieved and also variability that is based on the meticulousness of the pathologist.
Dr. Panzini is right to call attention to the importance of genetic syndromes in colorectal cancer. We did not emphasize it in the discussion because the assessment of a genetic component did not influence how we managed this patient's cancer. His family history was negative for colorectal neoplasms, however. We have no standard institutional policy with respect to the determination of microsatellite-instability status in colorectal cancers. The pathologist may select cases for microsatellite-instability determination on the basis of clinicopathological characteristics, which may include a family history of colorectal cancer, a right-sided tumor in a patient younger than 50 years of age, synchronous or metachronous colorectal cancers, or histologic findings suggestive of a tumor with microsatellite instability. Nevertheless, some clinicians worry about the long-term implications for the patient and family members when genetic tests are performed.
Paul C. Shellito, M.D.
Aaron P. Caplan, M.D.
Massachusetts General Hospital
Boston, MA 02114