Purpose: To test the safety, tolerability, and efficacy of interferon alpha 2b for conjunctival intraepithelial neoplasia (CIN) and to evaluate the risk factors associated with its clinical outcome. A secondary goal is to identify predictors of duration of treatment to achieve good results.
Methods: A prospective, noncomparative case series. Twenty-two patients with CIN were treated with interferon alpha 2b (1 million IU/mL) 4 times daily. Patients were evaluated by slit-lamp biomicroscopy, corneal histopathology, and impression cytology and the same physician carried out the diagnosis in all cases. Patients were monitored for relapses for 48 months after interferon therapy had ended. The following statistical tests were carried out: descriptive, bivariate correlation, and survival curves.
Results: Topical therapy eliminated clinical signs of disease in 91% of the cases (20 of 22). The average time to CIN resolution was 3.5 months (range 1-9), with only 4 patients presenting adverse effects (1 irritative conjunctivitis and 3 punctate keratitis). None of the 4 cases experiencing adverse reactions required discontinuation of therapy. Patients living in areas with high ultraviolet radiation levels had a longer clinical resolution (4.2 months) than those living in areas with low UV levels (1.8 months, P=0.01). There was association with statistical significance between the size of the lesion at the third month and treatment duration (P=0.048).
Conclusion: Topical interferon alpha 2b is an effective and safe treatment option for CIN. The place of residence can be a risk factor; areas like coast with higher UV levels result in a slower clinical resolution than inland areas. The size of the lesion after the third month of treatment with interferon can be a predictor of time to clinical resolution of CIN.