Topical 5-fluorouracil treatment of anal intraepithelial neoplasia in human immunodeficiency virus-positive men

Background Anal intraepithelial neoplasia (AIN), a human papillomavirus (HPV) induced potential precursor lesion of anal cancer, is frequent among human immunodeficiency virus (HIV)-positive men who have sex with men (MSM). So far, only a few prospective studies have been performed on the topical treatment of AIN, especially at the intra-anal location. Objectives To evaluate the efficacy and safety of self-administered topical 5-fluorouracil (5-FU) treatment of AIN in HIV-positive MSM. Methods High-resolution anoscopy (HRA) was performed and patients with AIN (grade 1-3) were treated with 5-FU twice weekly for a total of 16 weeks. HRA-guided lesional biopsies were repeated after 5-FU treatment for histopathological evaluation. Lesional swabs were obtained before and after treatment for HPV typing and HPV-DNA load determination of the high-risk types HPV16, 18, 31 and 33. Responding patients returned 6 months after treatment for follow-up. Results A total of 46 patients with AIN were included in this open prospective pilot study; 76% had multifocal disease and 74% had high-grade lesions (AIN 2 or 3). In an intention-to-treat analysis, 26 of 46 patients (57%) responded to 5-FU treatment. Eighteen patients (39%) had a complete clearance of AIN and eight patients (17%) had a partial response. Seventeen patients (37%) did not respond (unchanged grade of AIN in 16 patients and progression from low-to high-grade AIN in one patient). 5-FU treatment led to a significant decrease of HPV16-DNA load and cumulative high-risk HPV-DNA load in both responding and non-responding patients. Thirty-nine patients (85%) experienced side-effects during therapy, but only two discontinued 5-FU treatment. One patient was lost to follow-up. Six months later, 50% of the complete responders had a recurrence. Conclusions A substantial proportion of HIV-positive MSM with AIN completely cleared their lesions with topical 5-FU treatment. In those with partial response, pretreatment with topical 5-FU might facilitate subsequent ablative therapy.