Multiple primary tumors in patients with head and neck cancer.

From July 1978 to June 1984, 851 new cases of malignancies in the head and neck were registered in our hospital. Ninety-three patients with multiple primary tumors were observed. Triplicated malignancies were observed in three cases, i.e., larynx, thyroid, skin; stomach, tongue, larynx; and larynx, sarcoma, mesopharynx. The incidence rate was a high 30% in cancer of the mesopharynx (14/46), 14% in cancer of the larynx (55/392), and 7% in cancer of the hypopharynx. Additional primary malignancies occurred in the head and neck regions (25 cases), the digestive system (10 cases), the uro-reproductive system (18 cases), and others. Cancers of the stomach, lung, esophagus, and thyroid were predominant. Thirty-one cases (32.2%) were detected simultaneously and others were detected synchronously. We discuss the increased incidence rate of multiple primary tumors and the factors attributable to multiple primary tumors and stress the usefulness of systematic investigations.