Multiple primary malignant neoplasms of the head and neck.

This report analyzed the 7,763 cases treated at T.W.M.C., where radiotherapy has been mainly used, between 1968 and 1984. Of these, 258 cases (3.3%) had multiple primary malignant neoplasms, among which 88 cases involved head and neck cancer. The incidence averaged 1.6% during the first 5 years, but increased to an average of 5.7% during the last 5 years. Among head and neck cancer the incidence of multiple primary malignant neoplasms was 8.5% (88/1,033) and the incidence has been gradually increasing annually. Cancers of the head and neck were frequently combined with another primary lesion in the head and neck area or in the digestive tract, especially esophagus and stomach, followed by one in the both cases. The great majority of cancers in the head and neck occurred as the first cancer at age 60-70. The head and neck region is where the respiratory system and digestive system, including lymphatic organs originate and where the external carcinogenic factors enter into the body. These data suggested that multiple primary malignant neoplasms have been increasing in number and becoming an increasing problem. The possibility of multiple primary malignant neoplasms should not be forgotten in routine cancer related clinical work.