Preliminary results of intraoperative photodynamic therapy with 5-aminolevulinic acid in dogs with prostate carcinoma

Six client-owned dogs with prostate carcinoma were treated with a combination of (1) partial subcapsular prostatectomy using an Nd:YAG laser, (2) intraoperative photodynamic therapy using a halogen broad band lamp after local administration of a photosensitiser, and (3) systemic treatment with meloxicam. Median survival time was 41 days (range 10-68 days), which compared negatively with previous reports of subtotal laser prostatectomy combined with topical interleukin-2 administration, and photodynamic therapy alone. Despite treatment, the disease progressed locally, causing signs of stranguria to recur, and in the form of distant metastases. The recurrence of clinical signs due to the primary tumour despite photodynamic therapy is probably largely explained by insufficient penetration of light into the tissue. Better results may be obtained using other light sources (e.g. laser) and alternative techniques of light delivery, such as fibres or catheters allowing interstitial diffusion of light.