Risk of thyroid cancer in a nationwide cohort of patients with biopsy-verified celiac disease

Background: In earlier studies based on selected populations, the relative risk for thyroid cancer in celiac disease has varied between 0.6 and 22.5. We aimed to test this relationship in a population-based setting. Methods: We collected small intestinal biopsy report data performed in 1969-2008 from all 28 Swedish pathology departments. 29,074 individuals with celiac disease (villous atrophy; Marsh histopathology stage III) were matched for sex, age, calendar year, and county to 144,440 reference individuals from the Swedish general population. Through Cox regression, we then estimated hazard ratios (HRs) and confidence intervals (CIs) for any thyroid cancer and papillary thyroid cancer (defined according to relevant pathology codes in the Swedish Cancer Register) in patients with celiac disease. Results: During follow-up, any thyroid cancer developed in seven patients with celiac disease (expected=12) and papillary thyroid cancer developed in five patients (expected=7). Celiac disease was not associated with an increased risk of any thyroid cancer (HR 0.6 [CI 0.3-1.3]) or of papillary thyroid cancer (HR 0.7 [CI 0.3-1.8]). All cases of thyroid cancer in celiac disease occurred in female patients. Risk estimates were similar before and after the year 2000 and independent of age at celiac diagnosis (≤24 years vs. ≥25 years). Conclusions: We conclude that, in the Swedish population, there is no increased risk of thyroid cancer in patients with celiac disease. This differs from what has been reported in smaller studies in Italy and the United States.