Multiple primary malignant tumors (MPMT): study of 68 autopsy cases (1963-1980).

Review of 8428 autopsies (1870 for known cancer) showed that 68 patients had had multiple primary malignant tumors (MPMT). Those 68 cases represented 0.8 per cent of all autopsies done, 3.6 per cent of all cancer autopsies. Diagnosis of MPMT was made only at autopsy in 24 cases (35.3 per cent). Thirty-six patients were male, 32 female. Their average age was 64 +/- 2.3 years. Cancers were "synchronous" (diagnosed within a six-month period) in 15 patients, "metachronous" (diagnosed at greater than six-month intervals) in 49, and "combined" in four. Metastatic foci were seen in 53 patients. Fifty-nine patients had two primary malignant tumors (PMTs); seven had three PMTs; one had four PMTs; and one had five PMTs, for a total of 148 tumors. Over half (53.1 per cent) of the second PMTs occurred within five years of the first PMTs. First PMTs were most common in the hematopoietic system and the cervix; second PMTs were most common in the lungs and the hematopoietic system. Second PMTs were less well differentiated than index PMTs. Forty-four deaths had not been directly tumor-related. Nineteen patients with metachronous MPMT lived more than ten years. Of 23 patients with one pulmonary PMT, 22 died within two years. Concomitant findings of pulmonary artery embolism, gallstone(s), thyroid or prostatic hyperplasia, and benign tumor were common in these patients. It is hoped that accumulation of data from this and other series of MPMT will provide insight into the clinicopathologic characteristics, the causes, and the interrelationships of these lesions that constitute primarily a disease of the elderly.