[Colorectal cancer in the context of multiple primary malignant neoplasms]

The finding of more than one carcinoma throughout the life of a patient is not unusual. In fact, the occurrence of multiple primary cancers has been well documented. However, the features, implications and prognosis of colorectal cancers associated to other malignancies, have been less well documented.

We report 29 patients with multiple primary neoplasms in which at least one of them was a colorectal cancer. Number, extension and localization of colonic neoplasm, and time interval between diagnosis of both neoplasms, and mortality and survival rate were retrospectively analyzed. Follow-up ranged from 1 to 360 months.

Twenty three patients had two cancers, and six more than three neoplasms. Colorectal cancer was primary in 8 patients, metachronous in 14 patients and synchronous in 5 patients. Breast (7 cases), prostate (5 cases), endometrium (3 patients) and stomach (3 cases), were the other malignancies most frequently detected. Overall, 13 of the 27 patients (49%) died during the follow-up period after the recognition of the colorectal cancer. Two patients were lost to follow-up. Mantel-Haenszel test did not show significative differences in survival between patients with two or more neoplasms. There were no differences in survival depending upon the timing of diagnosis of the colorectal tumor.

These data suggest that colorectal cancer may share etiologic factors with hormone-dependent neoplasms (breast, prostate) and gastric cancer. In patients with primary multiple neoplasms, the number of neoplasms detected and the interval time between both diagnosis are not prognostic factors when one of the malignancies in colorectal cancer.