Differential survival trends for patients with tonsillar, base of tongue and tongue cancer in Sweden.

Tonsillar, base of tongue and tongue cancer have similar anatomical and histopathological appearances but present differences in prognosis. Human papillomavirus (HPV) is a known risk factor for tonsillar and base of tongue cancer, and a survival benefit has been shown for these tumors; however, HPV prevalence in tongue cancer is low. Tonsillar, base of tongue and tongue cancer patients registered in the Swedish Cancer Registry between 1960 and 2004 were followed from the date of cancer diagnosis until death, emigration out of Sweden, or the end of a follow-up (5 years since cancer diagnosis), whichever occurred first. The relative survival rate was computed as the ratio of the observed to the expected survival rate, in which the latter was inferred from the survival of the entire Swedish population in the same age, sex and calendar year stratum. The relative survival rate has improved significantly over time for patients with tonsillar and base of tongue cancer although delineated by different patterns. However, the relative survival rate in tongue cancer patients exhibited only a very modest improvement during the same time period. Contrary to the overall improved survival for patients with tonsillar and base of tongue cancer, the patients with tongue cancer show a very modest improvement in Sweden since 1960. Further studies are warranted to elucidate more effective treatment options for tongue cancer patients.