Multiple primary gastric and colorectal cancer in Japan.

The features of multiple primary gastric and colorectal cancer (MPGCC) were investigated, using 447 patients with primary gastric cancer and 199 with colorectal cancer during 1981-1992. Thirteen of these patients were found to have adenocarcinoma in both the stomach and colorectum. The increase rate for MPGCC and colorectal cancer was higher than that of primary gastric cancer (p < 0.05). Of the 13 patients with MPGCC, 8 showed synchronous MPGCC, while 5 showed metachronous MPGCC. Five of the 8 patients with synchronous MPGCC showed either Stage I or II in both lesions of the stomach and colorectum, and all 5 patients with metachronous MPGCC showed Stage I or II in the lesion of the second primary cancer. Since patients with MPGCC are expected to have a relatively good prognosis, both a preoperative examination and postoperative follow-up will be needed in order not to overlook lesions of the stomach or colorectum in patients with MPGCC.