Water-filtered infrared-A radiation: a novel technique for localized hyperthermia in combination with bacteriochlorophyll-based photodynamic therapy

A novel application of an infrared-A (IR-A) radiation source equipped with a water-filter in the radiation path is described, which allows for tumour treatment with a simultaneous combination of localized hyperthermia (HT) an d bacteriochlorophyll-serine (Bchl-ser) based photodynamic therapy (PDT). U sing this system, the IR-A radiation was used to heat tumours to 43 degrees C for 60 min, while at the same time activating the Bchl-ser which was inj ected i.v. at a dose of 20 mg/kg, 10 min following commencement of MT. The growth of tumours undergoing this combined therapy was compared to that of tumours undergoing HT alone or sham-treated controls. Within the 90 day obs ervation period, 100% of tumours in sham-treated animals, 80% in MT-treated animals and only 17% in HT + Bchl-ser-treated animals reached the end poin t target volume of 3.5 ml. Thus, the tumour growth inhibition effect of MT can be substantially enhanced by combination with Bchl-ser-PDT. This novel technique has proved to be well-tolerated, easy to apply and should be suit able for treatment of superficial malignancies, especially where hypoxic tu mour areas are present.