Photodynamic therapy with systemic meta‐tetrahydroxyphenylchlorin in the treatment of anal intraepithelial neoplasia, grade 3

Abstract

Anal cancer and preneoplastic anal lesions (anal intraepithelial neoplasia, AIN) rising especially in men having sex with men (MSM). There are no widely accepted treatment standards for AIN. Photodynamic therapy (PDT) using the systemic sensitizer meta-tetrahydroxyphenylchlorin (mTHPC) has the potential to treat the anal area even when the exact borders of the preneoplastic anal lesion cannot easily be visualized. In this prospective intervention study, 15 HIV-positive MSM with AIN 3 were treated in 25 PDT-sessions using mTHPC intravenously administered at drug doses of 0.075-0.15 mg ml(-1) and illumination at 48 hours. The illumination was performed using a custom made applicator using either red light (652 nm) to a measured intended fluence of 10 and 20 J cm(-2) and green light (532 nm) to a measured intended fluence of 105, 210, and 340 J cm(-2) . Red and green illuminations were performed at a (green) equivalent fluence rate of 105 mW cm(-2) . Initial complete response was seen in 7/25 (28%) of treatments and another 4/25 (16%) initial partial responses. After an average 8 months, recurrences were detected in 7/11 (64%) of sessions that initially showed response. A total 4/25 (16%) showed persistent complete response 6-15 months after green light illumination. Red light illuminations caused more significant side effects combined with no persistent complete response. Reported side effects were intense pain, bloody and purulent rectal discharge, and anal stricture formation, in one patient. The results show that the use of systemic mTHPC is partially effective for the treatment of AIN 3.