The role of prophylactic subtotal colectomy in metachronous carcinoma of the colon and rectum.

The risk of metachronous carcinoma of the colon and rectum at 40 year follow-up evaluation is as high as 30 percent. Because of this risk, we reviewed a series of 767 patients treated surgically for carcinoma of the colon and rectum to define a possible prophylactic role for subtotal colectomy. Patients being treated for metachronous carcinoma of the colon and rectum represented 1.6 percent of all patients undergoing surgical treatment for carcinoma of the colon and rectum during this period. There was an early group (less than 2.5 years) and a late group (greater than eight years); with respect to time interval between lesions, the early group possibly representing missed synchronous lesions. Forty-six percent of the patients had associated adenomas. Evaluation of the colon with preoperative colonoscopy may eliminate the "early" metachronous lesions that are probably missed synchronous lesions. The presence of adenomas in a younger patient with a primary carcinoma of the colon and rectum represents a high risk of future carcinoma. Subtotal colectomy should be considered in these patients and may also improve the life-long follow-up evaluation required by allowing proctosigmoidoscopy alone to evaluate effectively the remaining colon and rectum.