Recent trends in the incidence, geographical distribution, and survival from thyroid cancer in wales, 1985-2010

Background: Previous studies of thyroid cancer incidence in Wales have given varying results with suggestions of an excess of cases in geographic areas that were previously exposed to the radioactive fallout from the 1986 Chernobyl nuclear reactor incident. Our objective in this study was to provide an up-to-date comprehensive analysis of time trends in the incidence, geographical distribution, and survival from thyroid cancer in Wales. Methods: We identified thyroid cancer cases, registered from 1985 through 2010 in the Welsh Cancer Intelligence and Surveillance Unit (WCISU). Age standardized rates were determined from the European standard population. A Poisson regression model was fitted to assess temporal trends and rate ratios (RRs) and confidence intervals (CIs) were determined and compared across consecutive time periods: 1985-1997 and 1998-2010. Standardized incidence ratios were calculated for each of the 22 local authority areas. Relative survival and Kaplan-Meier curves were computed to analyze all cause and thyroid cancer-specific survival. Results: A total of 1747 thyroid cancer cases were registered from 1985 to 2010. Age standardized incidence rates were 2.8 and 1.2 per 100,000 population per year for females and males respectively. Incidence rates increased with time (RR 1.3 [CI 1.2-1.5], p65 years vs. 15-64 years) and patients with anaplastic thyroid cancer (p