Association between Genetic Risk, Adherence to Healthy Lifestyle Behavior, and Thyroid Cancer Risk

Abstract

Importance: Genetic and lifestyle factors are related to thyroid cancer (TC). Whether a healthy lifestyle is associated with TC and could attenuate the influence of genetic variants in TC remains equivocal. Objectives: To examine the associations between genetics and healthy lifestyle with incident TC and whether adherence to a healthy lifestyle modifies the association between genetic variants and TC. Design, Setting, and Participants: A prospective cohort study using UK Biobank data recruited 502505 participants aged 40 to 69 years between March 13, 2006, and October 1, 2010. A total of 307803 participants of European descent were recruited at baseline, and 264956 participants were available for the present study. Data analysis was conducted from November 1, 2021, to April 22, 2022. Exposures: Lifestyle behaviors were determined by diet index, physical activity, weight, smoking, and alcohol consumption. Lifestyle was categorized as unfavorable (scores 0-1), intermediate (score 2), and favorable (scores 3-5). The polygenic risk score (PRS) was derived from a meta-genome-wide association study using 3 cohorts and categorized as low, intermediate, and high. Main Outcomes and Measures: Thyroid cancer was defined using the International Classification of Diseases, Ninth Revision (code 193), International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (code C73), and self-report (code 1065). Results: Of 264956 participants, 137665 were women (52%). The median age was 57 (IQR, 49-62) years. During a median follow-up of 11.1 (IQR, 10.33-11.75) years (2885046 person-years), 423 incident TCs were ascertained (14.66 per 100000 person-years). Higher PRSs were associated with TC (hazard ratio [HR], 2.25; 95% CI, 1.91-2.64; P = 8.65 × 10-23). An unfavorable lifestyle was also associated with a higher risk of TC (HR, 1.93; 95% CI, 1.50-2.49; P