Relationship between tamoxifen and cataracts: a nationwide cohort study of women in South Korea

Purpose: Although prospective randomized clinical trials have reported that the use of prophylactic tamoxifen in patients at a high risk of breast cancer is associated with an increased risk of cataracts development, such findings are inconsistent. This study aimed to clarify the relationship between adjuvant tamoxifen use and cataracts risk using a nationwide longitudinal population-based registry. Methods: This retrospective cohort study was conducted using the Korean National Health Insurance claims database over a 15-year period (January 2007–December 2021). Data from all female patients diagnosed with ductal carcinoma in situ (DCIS) between 2009 and 2015 were extracted. We evaluated the incidence of cataracts diagnosis and surgery after adjuvant tamoxifen administration in patients with DCIS. Results: A total of 43,434 patients who met the inclusion criteria were diagnosed with DCIS between 2009 and 2015. Data from 2849 patients receiving tamoxifen and 1615 patients not receiving tamoxifen were analyzed before matching. After matching for comorbidities, type of breast surgery, and age, both groups consisted of 1597 patients. Both before and after matching, adjuvant tamoxifen was not a significant factor for an increased risk of cataracts diagnosis alone or with surgery. Conclusion: Our study showed that adjuvant tamoxifen was not a risk factor for increased cataracts diagnosis and surgery in patients with DCIS. This finding provides a basis for physicians to reduce their ocular toxicity concerns regarding the risk of patients developing cataracts by tamoxifen treatment.