Distinct features of second primary malignancies in head and neck cancer patients in Japan

Second primary malignancies (SPMs) are one of the most critical problems in treating head and neck cancer patients. Our hospital had 742 patients with a diagnosis of malignant head and neck tumors during the five-year period from 2002 to 2006. In this study, we analyzed 360 of those patients who were assumed to have risk factors such as alcohol and tobacco use: 106 oral, 120 laryngeal, 50 oropharyngeal and 84 hypopharyngeal cancer patients. Synchronous SPMs are defined as second cancers diagnosed at the same time or within 6 months of the diagnosis of the index head and neck cancers. There were 4 (3.8%) and 11 (10.4%) oral cancer patients, 11 (8.3%) and 8 (5.8%) laryngeal cancer patients, 7 (14.0%) and 4 (8.0%) oropharyngeal cancer patients, and 30 (28.6%) and 7 (8.3%) hypopharyngeal cancer patients with synchronous and metachronous SPMs, respectively. The number of metachronous patients with synchronous SPMs tended to increase during this time period. The frequencies of SPMs in oropharyngeal and hypopharyngeal cancer patients are similar to those in oral and laryngeal cancer patients. Notably, the most frequent SPMs are upper gastrointestinal tract cancers in Japan, compared to lung cancers in Europe. The five-year overall survival rate of patients with synchronous SPMs was significantly poorer than that of patients without any other tumor except for the index cancer, according to the Kaplan-Meier analysis. In conclusion, searching for SPMs in the upper gastrointestinal tract is a critical issue in head and neck cancer patients in Japan.