Trends in oral cancer by subsite in New Zealand.

A significant increase in incidence rates for all subsites of oral cancer in men and all but cancer of the salivary glands in women has occurred in New Zealand over the past 35 years. However, only male mortality rates of cancers of the nasopharynx and pharynx (excluding the nasopharynx) have significantly increased during this time period. Significant birth-cohort effects existed in the trends in incidence and mortality for cancers of the tongue, mouth, pharynx (excluding the nasopharynx), and nasopharynx among men. For cancers of the mouth and pharynx (excluding the nasopharynx) an increased risk for men born 1912-1932 existed, while an increased risk of cancer of the tongue occurred for men born 1922 onwards. For nasopharyngeal cancer, men born around 1912 and those born from about 1932 onwards were found to have an increased risk. For women, no consistent trends by birth-cohort were found for any oral subsite of cancer.