Descriptive epidemiology of thyroid cancer in the Swiss Canton of Vaud

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Abstract
Although substantial decreases have been recorded, age-standardized mortality rates from thyroid cancer in Switzerland are still the highest in Europe in men (0.9/100000), together with those from Austria, and the third highest (1.0/100 000) in women. Detailed analysis of 308 new cases registered between 1974 and 1987 in the Swiss Canton of Vaud revealed an overall incidence rate of 1.36/100000 men (world standard) in 1974–1980 and of 1.74/100 000 in 1981–1987. Corresponding values for women were 4.28 and 4.51, respectively. Thus, women constituted the majority of all cases (76%). Papillary carcinoma was the most frequent histological type (53%) followed by follicular (27%), undifferentiated (5%) and medullary (2%); other morphologies and clinical tumours accounted for 13% of the whole series. In both sexes, most of the apparent increase over the calendar period was restricted to the papillary type. Overall 5- and 10-year survival rates were 71% and 57%. When various factors were introduced in a Cox proportional-hazard model, young age at diagnosis (hazard rate for ≧65 years vs <45=14.7; 95% confidence interval=7.5–29.1) and good histological differentiation (hazard rate for papillary and follicular vs undifferentiated=0.4) emerged as strong favourable and independent prognostic factors. The reduced hazard rate for women, other factors being equal, was of borderline significance (0.7, 95% confidence interval=0.5–1.0), whereas no significant difference was observed between follicular and papillary carcinomas, and calendar periods of diagnosis.