ORIGINAL ARTICLE: PDF OnlyGamma radiation and MC540 photosensitization of melanoma in the hamster's eyeKukielczak, B.; Romanowska, B.; Bryk, J.Author Information Department of Radiospectroscopy and Radiobiology of Cancer, Institute of Molecular Biology, Jagiellonian University, Al. Mickiewicza 3, 31–120 Krakow, Poland (B. Kukielczak). Department of Ophthalmology, Collegium Medicum, Jagiellonian University, ul. Kopemika 38, 31–501 Krakow, Poland (B. Romanowska and J. Bryk). Laboratory of Pharmacology and Chemistry, NIEHS/NIH, 111 Alexander Dr., MD F0–06, Research Triangle Park, NC 27709, USA. Melanoma Research: April 1999 - Volume 9 - Issue 2 - p 115-124 Buy Abstract The purpose of this study was to evaluate the effects of cobalt-60 γ-radiation and argon laser Irradiation using Injected merocyanine (MC540) as a photosensitizer on pigmented and non-pigmented Bomirski hamster melanomas growing in the eye. The animals were treated with one of four regimens, receiving γ-irradiation only, photosensitization only, a combination of γ-irradiation and photosensitization, or a combined time-fractionated treatment. Tumours were exposed to laser light 24 h after injection, when the photosensitizing dye concentration was highest. The degree of tissue damage was evaluated by observation of the area for necrosis, interruption of blood circulation, and the shape and dissemination of the tumour cells. Additionally, tumour growth was monitored through the measurement of tumour volume and also calculated from histological cross sections on the assumption that the tumour morphology is hemi-ellipsoidal. A single treatment of tumours by a combination of photodynamic therapy and ionizing radiation resulted in an additive effect, inhibiting tumour growth for 2–4 days. A time-fractionated treatment, given four times every 24 h, markedly delayed tumour growth for up to 6 weeks. The results indicate that MC540-mediated photodynamic treatment in combination with γ-radiation exerts a significant therapeutic effect on a rapidly growing melanoma. © 1999 Lippincott Williams & Wilkins, Inc.