Topical 5-Fluorouracil 0.5% as primary treatment for Ocular Surface Squamous Neoplasia.

Purpose: To evaluate the efficacy of topical treatment with 5-Fluorouracil (5-FU) 0.5% in cases of Ocular Surface Squamous Neoplasia (OSSN), and to assess the tolerance of patients undergoing treatment.

Methods: Patients with clinical diagnosis of OSSN referred to the Ocular Oncology division from the Federal University of Sao Paulo, Brazil, were recruited for the current study. Patients were treated with topical 5-FU 0.5% using a regimen of 4 times daily for 10 days, followed by a 3-week drug holiday, continued up to 3 cycles before an alternative treatment. Lesions were evaluated at baseline and throughout treatment. Treatment adherence was assessed using the Morisky Medication Adherence scale. Any adverse events along the treatment were noted.

Results: A total of 30 eyes of 30 patients adherent to the treatment were included in the study. Among the total cases treated with 5-FU 0.5%, 24 patients achieved therapeutic success after a mean treatment duration of 21.71 ± 7.77 days, representing a success rate of 80.00% (95% CI: 60.75-91.18%). For each 1 mm2 increase in the lesion area, the odds of treatment success decrease by 6% (OR: 0.94; 95%CI: 0.88-0.99; p = 0.033). Only mild adverse events such as ocular discomfort, ocular burning and tearing were observed along the treatment in 8 patients.

Conclusions: Topical 5-FU 0.5% is an effective therapeutic option in the treatment of OSSN, with an 80% therapeutic success rate, showing good tolerability. The size of the lesion was identified as a factor influencing treatment success, therefore it should be taken into consideration when defining treatment approaches.