Effects of therapeutic radiation on the development of multiple primary tumors of the head and neck

Previous studies on the carcinogenesis of radiotherapy for head and neck tumors have been conflicting. A series of 1,856 head and neck cancer patients was classified into three groups based on treatment: 1) surgery alone, 2) surgery with pre- or postoperative radiotherapy, or 3) radiotherapy alone. Patients who were followed-up for longer than 5 years were used to compare the incidence of multiple primaries among the three groups. The overall incidence of multiple primary head and neck malignancies in this study was 9%. There was no significant difference in the incidence of multiple primaries in the groups treated by surgery alone versus the combined surgery and radiotherapy group. In this study, radiotherapy appeared neither to protect against nor induce multiple primaries within head and neck radiation portals.