Decreasing incidence and improved survival of laryngeal cancer in Finland.

The decreasing incidence rate and improvement in survival of laryngeal cancer patients in Finland are exceptions among western countries. A descriptive study of these trends was conducted including both nationwide population-based cancer registry data with 5 766 patients diagnosed in 1956-1995 and regional hospital-based data from Northern Finland, allowing classification into supraglottic and glottic cancers, with 353 patients diagnosed in 1976-1995. In Finland, the age-adjusted incidence rate among males decreased from 6.5 per 100 000 in 1956-1965 to 3.5 in 1986-1995, while in females the rate remained around 0.3 per 100 000. The rates in Northern Finland were slightly higher and the supraglottic to glottic incidence ratio diminished from 1.4:1 in 1976-1985 to 0.5:1 in 1986-1995. The 5-year relative survival rate improved in both Northern Finland and the whole country, most noticeably among males and the elderly. In the data from Northern Finland, the survival rate was more favourable in glottic (80%) than in supraglottic cancer (64%). Considering the marked decrease in the incidence of the less favourable supraglottic disease, the observed improvement in survival was small.