Role of topical interferon alpha-2b in 'mitomycin-C-resistant' ocular surface squamous neoplasia: our preliminary findings.

Abstract

To report the clinical presentation of mitomycin-C (MMC)-resistant ocular surface squamous neoplasia (OSSN) and its treatment outcome with topical interferon alpha-2b (IFNα-2b). A prospective, non-randomised, pilot study enrolling clinically diagnosed OSSN patients. The inclusion criterion was resistance of OSSN to standard topical MMC (0.02%) chemotherapy. The resistance was defined as 'no clinical response' in the terms of reduction in tumour size, extension and vascularity after minimum 6weeks 'on-cycles' of MMC. Any previous surgical intervention or recurrent OSSN lesions were excluded. Topical MMC was stopped in all, and topical IFNα-2b (1million IU/ml) eyedrops were prescribed to each patient. At first presentation, the clinical features and side-effect profile of MMC was noted and therapeutic effect of IFNα-2b was clinically monitored at each follow-up. Topical immunotherapy was continued for 24weeks and a minimum follow-up of 12weeks was observed after stopping IFNα-2b. Six patients with a mean age of 62years met the inclusion criteria. At presentation, all had unilateral, circumscribed, sessile and unifocal lesions with mean dimensions of 7.67×5.17mm. Four patients had temporal lesions while surface keratin, pigmentation and corneal involvement were noted in three lesions, separately. All lesions had dilated and tortuous feeder vessels. All six tumours resolved completely over a mean tumour resolution time of 16weeks while the total duration of IFNα-2b treatment was 24weeks. After stopping immunotherapy, a mean of 14.5weeks follow-up was observed. None showed any recurrence. The approximate cost of total therapy session was 8400 Indian rupees. The OSSN lesions showing 'less or no response' to topical MMC may be shifted to topical recombinant IFNα-2b before proceeding for a surgical excision.