Ocular Toxicity Associated with Tamoxifen Administration in Patients with Breast Cancer: A Systematic Review

Introduction: Tamoxifen (TAM), a selective Oestrogen Receptor (ER) modulator, is widely used for treating and preventing ERpositive Breast Cancer (BC). TAM, administered as an adjuvant therapy for hormone receptor-positive BC, reduces recurrence but can cause ocular toxicity, including retinal degeneration, macular oedema, and corneal changes. However, the underlying mechanisms behind these effects remain unclear. Aim: This systematic review aimed to evaluate the ocular toxicity induced by TAM in patients with BC and to assess the reported adverse events. Materials and Methods: A systematic review was conducted which included a comprehensive search of electronic databases and grey literature sources to identify relevant studies published between May 2018 and May 2024. Observational studies (case-control and cross-sectional) published in the English language that detailed the ocular Adverse Effects (AE) of TAM in patients with BC were considered for inclusion. Three reviewers screened the selected studies based on the title and abstract. Disagreements were resolved by discussion with another reviewer. Data extraction included study characteristics, patient demographics, intervention details, and ocular changes. Results: Five studies met the inclusion criteria and were included in the review. The analysis revealed that TAM-induced ocular toxicity results in diverse structural and functional changes within eye tissues, including retinal degeneration, macular thinning, alterations in choroidal thickness, and vascular modifications. The severity of ocular toxicity correlated with cumulative TAM exposure, highlighting the need for long-term eye monitoring in patients receiving extended therapy. Conclusion: This systematic review indicated a possible link between TAM use and ocular toxicity, although the evidence is limited by methodological constraints. These results highlight the necessity of eye monitoring for patients undergoing TAM treatment, especially for those receiving long-term regimens.