Synchronous carcinomas of the large intestine.

Sixty-one (3.0%) of 2029 patients managed operatively for carcinoma of the large intestine had synchronous carcinomas. In 47 (77.0%) of the 61 patients the carcinomas were in the same or adjacent segment(s) of large intestine. Adenomatous polyps were present in 18 (30%) patients compared to 269 (14%) of 1968 patients with a single cancer. A curative resection was performed in 40 of 61 patients, palliative resection in 16 and a non-resection palliative operation in five. Two patients required proctocolectomy and eight subtotal colectomy with ileorectal anastomosis. Cancer specific survival for the entire group and for those treated by curative resection did not differ significantly from that of patients with a single carcinoma. It is concluded that: (1) the presence of a second carcinoma does not significantly alter the survival prospects; (2) both pre-operative large intestinal examination and careful operative palpation of the entire large intestine should be performed, and (3) the significantly higher incidence of adenomatous polyps in patients with synchronous carcinomas is consistent with the polyp/cancer sequence hypothesis.