FREQUENCY AND CLINICAL-FEATURES OF MULTIPLE TUMORS OF THE LARGE-BOWELIN THE GENERAL-POPULATION AND IN PATIENTS WITH HEREDITARY COLORECTAL-CARCINOMA

BACKGROUND. Reports on the frequency of multiple carcinomas of the col on and rectum have varied from 3-4% to more than 10% of all tumors of the large bowel.METHODS. We reviewed the files of a specialized colore ctal cancer registry with chronous or metachronous) in the general pop ulation; b) to compare these values with those observed in patients wi th hereditary nonpolyposis colorectal carcinoma the following objectiv es: a) to determine the frequency of multiple tumors (synchronous or m etachronous) in the general population; b) to compare these values wit h those observed in patients with hereditary nonpolyposis colorectal c arcinoma (HNPCC); and c) to evaluate the clinical outcome of patients with multiple tumors and the role of other clinical parameters in the development of these neoplasms. RESULTS. From 1984 to 1992, 53 patient s with multiple tumors (of 1298 registered patients, 4%) had large bow el carcinoma; 33 (2.5%) were synchronous and 20 (1.5%) metachronous. T he total number of multiple colorectal carcinomas was 95, which was 7% of all registered colorectal carcinomas (1337 carcinomas in 1298 pati ents). Multiple tumors occurred significantly more often in patients w ith HNPCC than in those with sporadic carcinomas (P < 0.001); this inc reased prevalence was more marked for metachronous lesions, which occu rred almost 4 times more often in patients with HNPCC (5.8% vs. 1.3%; P < 0.001). The average interval of time between the first and the sec ond malignancy was 8.7 years; there was no significant difference betw een hereditary and sporadic tumors. Patients with synchronous tumors d id not show appreciable differences in survival when compared with ind ividuals who had single neoplasms. In contrast, a poor clinical outcom e was observed in patients with metachronous tumors after the developm ent of the second carcinoma. Finally, polypoid adenomas of the large b owel were found significantly more often in patients with multiple pri mary tumors than in those with a single tumor. CONCLUSIONS. These resu lts emphasize the importance of preoperative pancolonoscopy for the id entification of possible synchronous tumors (both benign and malignant ) and long-lasting endoscopic follow-up for the detection of recurrent or metachronous lesions. The conclusions are even more pertinent for patients with HNPCC, whose risk of metachronous tumors is significantl y higher than that of patients with sporadic carcinoma. (C) 1996 Ameri can Cancer Society.