Association between ¹³¹I treatment for thyroid cancer and risk of receiving cataract surgery: A cohort study from Taiwan

The risk of cataracts after 131I therapy for cancer is unknown. The objective of this study was to evaluate the association between 131I therapy for thyroid cancer and risk of receiving cataract surgery in Taiwan. Methods: This was a nationwide populationbased cohort study of patients with thyroid cancer diagnosed during the period 1998-2008. The data were obtained from the Taiwan National Health Insurance Research dataset. The cumulative 131I activity in each patient was calculated. Hazard ratios were calculated using a time-dependent survival analysis to estimate the effect of 131I therapy on the risk of receiving cataract surgery. Results: A total of 8,221 patients were eligible for the final analysis (mean age, 43.2 y; mean follow-up, 5.9 y); 69% received 131I with a median cumulative activity of 3.7 GBq. Two hundred patients received cataract surgery. The adjusted hazard ratios were 0.77 (95% confidence interval, 0.54-1.09), 0.92 (95% CI, 0.64-1.31), and 1.06 (95% CI, 0.58- 1.94) for cumulative 131I activities of 0.1-3.6, 3.7-7.3, and 7.4 GBq or more, respectively, compared with a cumulative activity of 0. No trend was noted (P > 0.85). No interaction between 131I activity and age or between 131I activity and sex was noted (all P > 0.05). Conclusion: 131I treatment for thyroid cancer did not increase the risk of receiving cataract surgery up to 10 y after treatment. However, further research with direct lens examination and a longer follow-up period is needed to assess subtle and late adverse effects beyond 10 y. COPYRIGHT