http://repub.eur.nl/res/aut/54723/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/37385/ 2012-10-01T00:00:00Z Background and Objective 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. Study Design/Materials and Methods 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-1and 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-2and 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. Results 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. Conclusion The results show that the use of systemic mTHPC is partially effective for the treatment of AIN 3. Lasers Surg. http://repub.eur.nl/res/pub/34618/ 2011-10-01T00:00:00Z The objective quantitative monitoring of light, oxygen, and photosensitizer is challenging in clinical photodynamic therapy settings. We have previously developed fluorescence differential path-length spectroscopy (FDPS), a technique that utilizes reflectance spectroscopy to monitor microvascular oxygen saturation, blood volume fraction, and vessel diameter, and fluorescence spectroscopy to monitor photosensitizer concentration. In this paper the clinical feasibility of the technique is tested on eight healthy volunteers and on three patients undergoing PDT of oral cavity cancers. Model-based analysis of the measured spectra provide quantitative tissue parameters that are corrected for background tissue absorption, autofluorescence, and the transmission of the optical system; this method allows comparison of intra- and inter-subject parameters. The FDPS correctly estimated the absence of m -THPC in volunteers and detected photobleaching in the areas receiving treatment light in patients undergoing PDT treatment. This study demonstrates the feasibility of monitoring clinical photodynamic therapy treatments using optical spectroscopy.