USING GENETIC INFORMATION TO MAKE SURGICAL DECISIONS - REPORT OF A CASE OF A 13-YEAR-OLD BOY WITH COLON-CANCER

PURPOSE: We report the case of a boy aged 13 years who was diagnosed w ith a Dukes B obstructing cancer of the sigmoid colon. At the time of diagnosis, he underwent a Hartmann's procedure with end colostomy. Bec ause of his unusually young age, he was referred to the Familial GI Ca ncer Registry at Mount Sinai Hospital fur genetic assessment. A detail ed pedigree revealed no significant history other than lung cancer in his maternal grandfather. METHODS: We obtained his tumor specimen and performed molecular analysis of both normal colonic and tumor DNA. Spe cifically, we identified replication errors (RER) in the patient's tum or DNA when compared with normal colonic DNA. RER has been found in mo re than 90 percent of tumors from patients with Hereditary Nonpolyposi s Colon Cancer (HNPCC) and is, thus, considered to be one of the hallm arks of this disease. Because HNPCC patients have a 40 percent risk of synchronous or metachronous tumors, the recommended surgery for HNPCC should be at least a subtotal colectomy with ileorectal anastomosis. RESULTS: Based on molecular results, we were able to recommend that th e patient have a subtotal colectomy performed instead of merely colost omy closure, to reduce his lifetime risk of developing further colon r umors and to malic surveillance of the remaining rectum relatively eas y. In this patient, we subsequently identified a germline mutation of the mismatch repair gene hMSH2 that is implicated in HNPCC. The possib ility of HNPCC should be considered in adolescents who are diagnosed w ith colorectal cancer, so appropriate surgical decisions can be made.