[Multiple primary cancers of the head and neck].

Multiple primary cancers of the head and neck are not always rare. We have experienced 30 cases of multiple primary cancers in the Department of Otolaryngology, Ehime University School of Medicine from 1976 to 1989. The incidence ranged from 3.6% to 8.9% with flexible criteria. The minimum was 14 of 393 cases of all index cancers, strictly conformed with Warren's definition. The maximum was 29 of 327 cases of index cancers on the mucosal surfaces, including a combination of both head and neck cancers. In view of organic specificity of the index cancers, the incidence was high in the larynx and oral cavity, low in the nasopharynx and maxillary sinus. The concept of "multicentric cancerization" was verified by the result that 60% of the additional cancers were head and neck, esophagus and lung. During following-up studies of oropharyngeal, hypopharyngeal and laryngeal cancers, we have to examine the esophagus periodically due to high risk of occurrence of cancer. To compare the data of multiple primary cancers of the head and neck between institutions, adequate and detailed criteria should be established.