Occupational radiation exposure and risk of thyroid cancer: A meta-analysis of cohort studies

The association between occupational exposure to ionizing radiation and the risk of thyroid cancer remains unclear in medical research. The present meta-analysis assessed whether occupational radiation exposure increases the risk of thyroid cancer. The PubMed, China National Knowledge Infrastructure, Embase, ChinaInfo, Weipu and Chinese Biomedical Literature databases were comprehensively searched for cohort studies published up to January 1st, 2023, using medical subject headings and keywords. Subsequently, a meta-analysis was conducted to determine a pooled-effect estimate of the association between occupational exposure and thyroid cancer. Subgroup analyses by sex were performed. The results were presented as the overall odds ratio (OR) and 95% confidence interval (CI). A total of six studies (covering 3,409,717 individuals), which were published between 2006 and 2021 from 4 countries met the inclusion criteria. The number of participants per study ranged from 67,562 to 2,992,166 and the number of cancer events in each study ranged from 134 to 2,599 cases. Pooled analyses indicated that occupational radiation exposure was associated with a 67% higher risk of thyroid cancer (OR=1.61, 95% CI: 1.27-2.04, P<0.001). Male patients with a history of occupational radiation exposure exhibited a slightly higher risk of thyroid cancer than female patients (OR=1.74, 95% CI: 1.61-1.87, P=0.726 vs. OR=1.30, 95% CI: 1.15-1.48, P=0.032). Collectively, the data indicated that occupational exposure to ionizing radiation was associated with the risk of thyroid cancer. However, further studies are warranted to confirm these preliminary findings.