Associations between body mass and papillary thyroid cancer stage and tumor size: a population-based study

The incidence of large thyroid tumors has increased over the past decades, suggesting that improved diagnosis is not the only driver of increased thyroid cancer incidence. Obesity has recently been implicated as an independent risk factor for thyroid cancer in specific populations. We aimed to investigate whether thyroid tumor size and advanced stage of diagnosis is associated with the obesity epidemic, for the first time, in a US population-based cohort. We leveraged existing data and linked 1,077 papillary thyroid cancer patients from the Nevada Central Cancer Registry to the Department of Motor Vehicle dataset. Tumor size and cancer stage were assessed from cancer registry records, and obesity was obtained using height and weight in the Department of Motor Vehicle records and measured by a body mass index greater than 25 kg/m(2). Crude analysis showed obesity as was associated with tumors larger than 2 cm [odds ratio (OR) 1.50, p = 0.0423] and advanced cancer stage (stage III and IV) (OR 1.40, p = 0.0111). After adjusting for confounders, a significant association was still observed between obesity and tumor larger than 2 cm (OR 1.53, p = 0.0339). A marginally significant association was shown between obesity and advanced cancer stage (OR 1.29, p = 0.0649). As thyroid cancer incidence continues to increase, this study's finding that obesity was significantly associated with larger tumor size and marginally significantly associated with advanced tumor stage can help establish new preventative actions and identify new target populations for interventions.