Photodynamic therapy using meso tetra hydroxy phenyl chlorin (mTHPC) in early prostate cancer

Abstract

Background and objectives: Prostate cancer is increasing in incidence, but current treatments including surgery and radiotherapy have significant side effects. This pilot study was designed to assess the potential of photodynamic therapy (PDT) using meso tetra hydroxy phenyl chlorin (mTHPC) for organ confined prostate cancer.

Study design/patients and methods: Six men with organ confined prostate cancer were photosensitised with mTHPC (0.15 mg/kg). Between 2 and 5 days later, red light (652 nm) was delivered to areas of biopsy proven cancer via fibres inserted through transperineal needles (50-100 J per site).

Results: After 8 of 10 PDT sessions, the prostate specific antigen (PSA) fell by up to 67%. Early MRI scans showed oedema and patchy necrosis, which resolved over 2 months. Biopsies of treated areas revealed necrosis and fibrosis at 1-2 months.

Conclusions: PDT for primary prostate cancer appears safe and can reduce PSA levels. As this was a phase I study, no attempt was made to treat the whole prostate; this or targeted tumour ablation could be attempted in a phase II study with an increased number of fibres. This technique merits further investigation in early prostate cancer.