Second Primary Cancers Following Colorectal Cancer

1. Evans HS, Moller H, Robinson D, Lewis CM, Bell CM, Hodgson SV. The risk of subsequent primary cancers after colorectal cancer in southeast England. Gut 2002;50:647-52. 2. Lee JW, Kim JW, Kim NK. Clinical characteristics of colorectal cancer patients with a second primary cancer. Ann Coloproctol 2014;30:18-22. 3. Travis LB, Rabkin CS, Brown LM, Allan JM, Alter BP, Ambrosone CB, et al. Cancer survivorship: genetic susceptibility and second primary cancers: research strategies and recommendations. J Natl Cancer Inst 2006;98:15-25. 4. Metayer C, Lynch CF, Clarke EA, Glimelius B, Storm H, Pukkala E, et al. Second cancers among long-term survivors of Hodgkin’s disease diagnosed in childhood and adolescence. J Clin Oncol 2000; 18:2435-43. 5. Umar A, Boland CR, Terdiman JP, Syngal S, de la Chapelle A, Rüschoff J, et al. Revised Bethesda Guidelines for hereditary nonpolyposis colorectal cancer (Lynch syndrome) and microsatellite instability. J Natl Cancer Inst 2004;96:261-8. 6. Hemminki K, Li X, Dong C. Second primary cancers after sporadic and familial colorectal cancer. Cancer Epidemiol Biomarkers Prev 2001;10:793-8. 7. Lynch HT, de la Chapelle A. Genetic susceptibility to non-polyposis colorectal cancer. J Med Genet 1999;36:801-18. 8. Win AK, Lindor NM, Young JP, Macrae FA, Young GP, Williamson E, et al. Risks of primary extracolonic cancers following colorectal cancer in lynch syndrome. J Natl Cancer Inst 2012;104:1363-72. 9. Canto MI, Goggins M, Yeo CJ, Griffin C, Axilbund JE, Brune K, et al. Screening for pancreatic neoplasia in high-risk individuals: an EUS-based approach. Clin Gastroenterol Hepatol 2004;2:606-21. Compared with the general population, individuals with a previous colorectal cancer have an elevated risk of a second primary cancer [1, 2]. Possible reasons for this phenomenon could be (1) an overall greater predisposition to cancer due to the same environmental and genetic factors that contributed to the first primary cancer [3] and (2) the second cancers possibly being related to the effects of treatment for the first cancer [4]. Lynch syndrome is an autosomal, dominant, inherited disorder of cancer susceptibility caused by germline mutations in DNA mismatch repair (MMR) genes. Mutation carriers are prone to developing cancers of the colon, rectum, endometrium, ovary, stomach, small intestine, urinary tract, kidney, biliary tract, and nervous system, and the diagnosis of these cancers generally occurs at a younger age than it does for non–MMR-related cancers [5]. Second cancers following colorectal cancer have essentially two types of patterns: Lynch-syndrome-associated cancers and cancers with no features of Lynch syndrome, which include breast, pancreas, prostate, and thyroid cancers [6-8]. An increased surveillance strategy could lead to earlier identification and removal of both premalignant lesions and early-stage tumors. Any patients diagnosed with colorectal cancer at a young age are at high risk of having a second colorectal cancer and should be followed-up at regular intervals [6]. Furthermore, in surveillance of these patients, all Lynch-syndrome-related sites should be considered. However, given the limited evidence for the efficacy of screening for breast, pancreas, prostate, and thyroid cancers [8, 9], further studies are needed to verify the validity of screening for these cancers in Lynch syndrome.