Multiple primary cancers in patients with initial laryngeal cancer.

The risk of a person developing a second primary cancer was evaluated in 1,215 patients with laryngeal cancer at the National Cancer Center Hospital. Overall, 92 (8.2%) of the male patients and 5 (5.7%) of the female patients developed a second cancer, compared with 83.0 and 3.7, respectively, expected on the basis of general population rates, resulting observed: expected values (O/E) to be 1.1 and 1.3. The numbers of second cancers of the lung (O/E = 1.9), oropharynx (O/E = 8.8) and esophagus (O/E = 2.8) were significantly in excess of those expected, while the number of second stomach cancers (O/E = 0.5) was far below expectation. Synchronous second cancers were significantly higher than expected (O/E = 4.6). Smoking, especially heavy smoking, was related to second lung cancers, but alcohol drinking featured less. Histories of benign respiratory tract and digestive organ diseases were related to second oropharyngeal cancers. Alcohol drinking was related to second stomach cancers. Radiation therapy for the initial laryngeal cancer was related to second oropharyngeal cancers, while hazardous occupations related to noxious agents for respiratory systems featured more prevalently in cases of second lung cancer. Further analytical studies should clarify the roles of smoking, drinking, occupation and various forms of therapy on the risk of developing a different second cancer following laryngeal cancer.