Recent trends in the incidence, geographical distribution, and survival from thyroid cancer in Wales: 1985-2010.
Title: Recent trends in the incidence, geographical distribution, and survival from thyroid cancer in Wales: 1985-2010.
Author: Amphlett B, Lawson Z, Abdulrahman GO, White C, Bailey R, Premawardhana L, Okosieme OE.
Reference: Thyroid. 2013 Mar 14. [Epub ahead of print]
Keywords:
Abstract: Abstract 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 standardised rates were determined from the European standard population. A Poisson regression model was fitted to assess temporal trends and rate ratios (RR) and 95% confidence intervals (CI) were determined and compared across consecutive time periods: 1985-1997 and 1998-2010. Standardised incidence ratios were calculated for each of the 22 local authority areas. Relative survival and Kaplan Meier curves were computed to analyse all cause and thyroid cancer-specific survival. Results A total of 1747 thyroid cancer cases were registered from 1985-2010. Age standardised incidence rates were 2.8 and 1.2 per 100,000 population per year for females and males, respectively. Incidence rates increased with time (rate ratio 1.3, 95% CI 1.2-1.5, p<0.001, 1998-2010 vs.1985-1997). The incidence of papillary cancer increased progressively over the study period (RR 2.22, 95% CI 1.91-2.57, p<0.001; 1998-2010 vs.1985-1997), while rates for other (non-papillary) histological subtypes remained static (RR 0.95, 95% CI 0.84-1.08, p=0.45; 1998-2010 vs.1985-1997). We identified two geographical areas of increased incidence but the spatial distribution of cases was inconsistent with exposure to radioactive fallout. Five-year relative survival from all-cause mortality improved from 74.2 (95% CI 66.8-80.1) in 1985-1989, to 82.6 (95% CI 77.1-86.9) in 2000-2004 but remained poor for patients >65 years (p<0.001, >65 yrs vs. 15-64 years) and patients with anaplastic thyroid cancer (p<0.001, anaplastic vs. other histological varieties). Conclusions The incidence of thyroid cancer has increased in Wales, predominantly due to an increase in papillary cancers. The current geographical distribution of cases does not support a radiation effect in the region. Survival has remained poor for patients aged >65 years and those with anaplastic carcinoma.
URL: http://www.ncbi.nlm.nih.gov/pubmed/23488941
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