A Trial of Radiofrequency Ablation for Anal Intraepithelial Neoplasia Using the HALO Ablation System

Inclusion Criteria: * Age 18-75 years * HRA 2 to 12 weeks prior to the 0 month RFA visit yielding one or more flat, non-condylomatous biopsy-proven HSILs that are 1. Located entirely within in the eligible treatment zone 2. Contiguous with the squamocolumnar junction Eligible treatment zone (ETZ) is defined as <!-- --> 1. 3 cm above the dentate line to the anocutaneous line 2. Half of the anorectal circumference (meaning no more than two contiguous quadrants) * If female of child-bearing age, negative pregnancy test within 8 weeks of the 0 month RFA visit and declared intent to remain on birth control throughout the trial, or, declaration of infertility defined as subject report of status as post-menopausal or surgically sterile (status post hysterectomy or tubal ligation). * HIV negative, ELISA/Western blot test obtained within 12 weeks of the 0 month RFA visit Exclusion Criteria: 1. Any biopsy-proven HSIL entirely outside of the ETZ 2. Any biopsy-proven HSIL partially within the ETZ (for example, an HSIL lesion with extension to the perianal skin) 3. Any condylomas in the eligible treatment zone \> 1/2 cm diameter • Note: Condylomas in the eligible treatment zone \< 1/2 cm in diameter must be excised or cauterized (not treated topically or with IRC) before or during Visit 1 (0 month RFA visit) 4. Any anal or rectal pathology requiring treatment including ulcer, fistula, fissure, stenosis or proctitis 5. History of or present anal or rectal cancer 6. History of pelvic radiation therapy 7. History of HPV vaccination or plans to initiate HPV vaccination during the trial 8. History of ablation or resection therapy within the ETZ other than cauterization or excision of condyloma(s) 9. History of topical therapy (Imiquimod, 5-FU) within 6 months prior to the 0 month RFA visit within the ETZ 10. Hemorrhoids \> grade II 11. Fecal incontinence (that the investigator feels may impair healing) 12. Concurrent disease requiring systemic immunosuppression therapy 13. Concurrent malignancy requiring systemic therapy 14. Life expectancy \< 2 years