[Multiple primary malignancies in patients with head and neck cancer]

From July, 1978 to December, 1985, 1,138 cases of malignancies of the head and neck were treated at the authors' hospital, and up to June, 1986, 132 patients with multiple primary malignancies were detected. In all cases, the incidence rate of a multiple primary malignancy was 11.6%. In 45 (33.0%) of these head and neck cancer cases, the multiple cancer was detected simultaneously, and as for the other cases (66.7%), they were discovered metachronously. In patients with a cancer of the mesopharynx, the incidence rate of a multiple primary malignancy was the highest (25.8%), whereas in those with a cancer of the parotid gland and in those with a cancer of the hypopharynx, the incidence rates were 20.0% and 14.9%, respectively. In most patients the second malignancy occurred in the same head and neck region, and in the rest, the second malignancy was a gastric cancer, a lung cancer, or an esophageal cancer in that descending order. Of the 45 synchronous cancer cases, ten were a thyroid cancer, most being latent. In head and neck malignancies, the authors stress the importance of a precise investigation prior to start of therapy and of maintaining follow-up investigations after therapy.