Adolescent and mid-life diet and subsequent risk of thyroid cancer in the NIH-AARP diet and health study

Although thyroid cancer is suspected to have a nutritional etiology, prospective studies examining the relationship between diet and thyroid cancer are lacking. During 1996-1997, NIH-AARP Diet and Health Study participants, ages 51-72 years, completed a 37-item food frequency questionnaire about diet at ages 12-13 years (adolescence) and 10 years before baseline (mid-life). Over a median 10 years of follow-up, 325 individuals (143 men and 182 women) were diagnosed with thyroid cancer. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for intakes of foods and food groups comparing the highest to the lowest quartiles. Adolescent intakes of chicken/Turkey (HR = 1.59, 95% CI: 0.97-2.60; p_trend < 0.01) and sweet baked goods (HR = 1.59, 95% CI: 1.09-2.34; p_trend = 0.04) were positively associated with thyroid cancer risk, while intake of butter/margarine was inversely associated with risk (HR = 0.64, 95% CI: 0.44-0.91; p_trend < 0.02). Similar to adolescent diet, mid-life intake of sweet baked goods was nonsignificantly associated with an increased risk of thyroid cancer (HR = 1.39, 95% CI: 0.96-2.00; p_trend = 0.11), but intake of butter/margarine was inversely associated with risk (HR = 0.66, 95% CI: 0.46-0.95; p_trend = 0.03). Among men, higher adolescent consumption of canned tuna was positively associated with risk of thyroid cancer (HR = 1.69, 95% CI: 1.01-2.83; p_trend = 0.03), and greater mid-life intake of broccoli was associated with a twofold increased risk (HR = 2.13, 95% CI: 1.13-3.99; p_trend < 0.01). This large prospective study suggests that several components of the adolescent and mid-life diet, including iodine-rich foods and goitrogens, may influence thyroid cancer risk. What's new? Nutritional factors in adolescence and mid-adulthood may influence the chances of developing malignant thyroid disease later in life, though studies designed to explore that idea are lacking. Here, the relationship between diet and thyroid cancer was studied prospectively in a large cohort of individuals enrolled in the NIH-AARP Diet and Health Study. The data indicate that thyroid cancer risk is associated with dietary factors in adolescence and mid-life. The association was strongest for the intake of iodine-rich foods and goitrogenic foods, such as broccoli.