Thyroid cancer in Vaud, Switzerland: an update.

We reviewed the descriptive epidemiology of thyroid cancer using data from the Cancer Registry of the Canton of Vaud, Switzerland, a consistently well-surveilled population with relatively high rates of the disease, between 1974 and 1998, on the basis of a total of 596 registered cases. Overall thyroid cancer incidence tended to increase moderately in both genders over the 25-year period considered, to reach rates of 5.4 and 2.0 per 100,000 (world standard) in females and males, respectively. There were also changes in histologic classification, with some increases in papillary neoplasms and corresponding decreases in other and unclassified ones. Ten-year relative survival rates for cases diagnosed in 1988-1993 were 94% for papillary cancer in females and 69% in males, and 59% for follicular cancer in females. Corresponding figures were 12% for undifferentiated, and 31% for other and unspecified neoplasms in both sexes combined. Multivariate analysis confirmed the unfavorable influence of male gender (hazard ratio [HR] = 1.9), elderly age (HR = 16.5 for age > or = 65 vs. < 45 years) and undifferentiated histotype (HR = 3.5 vs. papillary) on the long-term prognosis of thyroid cancer, and showed no consistent evidence of appreciably improved prognosis over more recent calendar periods.