Clinical problems of multiple primary cancers including head and neck cancers. From the viewpoint of radiotherapy

A total of 2144 head and neck cancers were treated by radiotherapy at the National Sapporo Hospital between 1974 and 2001. Of these, 313 (14.6%) were found to have other primary cancers besides head and neck cancer, in which double cancers were 79% and triple or more cancers were 21%. Frequency according to primary site of the first head and neck cancer was oral cavity: 107/603 (17.7%), epipharynx cancer: 7/117 (6.0%), oropharyngeal cancer: 63/257 (24.5%), hypopharyngeal cancer: 65/200 (32.5%), laryngeal cancer: 114/558 (20.4%), and nose/paranasal sinus: 4.9% respectively. Esophageal cancer, head and neck cancer, lung cancer and gastric cancer were very frequent as other primary sites combined with the head and neck. The first onset region was the head and neck in 233 out of 313 cases with multiple primary cancers. The five-year survival rate from the onset of head and neck cancers is 52%, 10-year: 30%, and 5-year cause-specific survival rate 82%, and 10-year: 78%, respectively. The treatment possibilities in multiple primary cancers tend to be limited because the treatment areas are sometimes overlapped. New approaches to the treatment of multiple primary cancers should be considered in the future. (author)