PURPOSE: To investigate the associations of anthropometric factors and physical activity with risk of thyroid cancer in a large prospective study.METHODS: We examined these associations with risk of incident thyroid cancer in a cohort of 144,319 postmenopausal women enrolled in the Women's Health Initiative. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) for factors of interest with risk of all thyroid cancer (n = 294) and of the two major subtypes: papillary (n = 245) and follicular thyroid cancer (n = 32).RESULTS: After adjustment for covariates, measured height at baseline was positively associated with thyroid cancer overall (HR for highest vs. lowest quartile 1.48, 95% CI 1.04-2.13, p for trend 0.02) and with papillary carcinoma (HR 1.49, 95% CI 1.01-2.21, p for trend 0.03, respectively). For each 5 cm-increase in height, the HR for all thyroid cancer was 1.15, 95% CI 1.04-1.27 and for papillary thyroid cancer was 1.14, 95% CI 1.03-1.27. In addition, self-reported weight at age 18 was positively associated with risk of papillary thyroid cancer. In contrast, baseline weight, body mass index, waist circumference, hip circumference, waist-hip ratio, weight change from age 18 to baseline, and level of self-reported recreational physical activity were not associated with risk.CONCLUSIONS: Our results suggest that attained stature is a risk factor for thyroid cancer in postmenopausal women. This association may reflect the influence of either genetic or environmental factors in early life on risk of thyroid cancer.
Anthropometry Body Mass Index