Dietary patterns and thyroid cancer risk: a population-based case-control study

Purpose: Thyroid cancer (TC) incidence has increased greatly during the past decades with a few established risk factors, while the relationship between dietary factors and TC remains unclear. Limited literature has investigated the association with inconsistent findings. Methods: We examined the association between dietary pattern and risk of TC in a population based case-control study conducted in Connecticut (2010-2011). Our study population included 390 historically confirmed incident TC cases and 436 population-based controls who completed baseline dietary history questionnaires (DHQ). We identified 3 distinct dietary patterns ("Starchy Foods and Desserts", "Fruits and Vegetables", "High Protein and Fat") through principal components analysis. Multivariate unconditional logistic regression models were used to investigate the association between each dietary pattern and risk of TC, controlling for potential confounders. Results: A diet rich in fruits and vegetables was significantly associated with a reduced risk of overall TC (OR = 0.60, 95% CI: 0.39, 0.92; P-trend = 0.02). Compared to younger women, a stronger protective effect was observed among women >= 50 years of age in overall TC and papillary TC risk. A diet rich in starchy foods and desserts was positively and negatively associated with an overall TC risk among men and women respectively. Conclusions: Our study found a significant negative association between diet patterns rich in fruits and vegetables and TC risk, especially among women aged 50 years or older. While high in starchy foods and desserts may be positively and negatively associated with TC risk among men and women respectively, these results require confirmation in other populations.