Hematoporphyrin derivative (HPD) is retained by malignant tumors and emits fluorescence with peaks of 630 and 690nm wavelength when HPD is exposed to light. It is therefore theoretically possible to make a diagnosis of malignant tumors by detecting the fluorescence of HPD. The authors developed a spectroscope system compatible with fiberoptic endoscopes to analyze the shape of the fluorescence light spectrum. We could clearly recognize the HPD-specific fluorescence in human cancer foci. This system can be applied to the measurement of the relative amount of HPD absorbed in superficial tumor tissue before the photodynamic therapy. This might suggest the extent of tumor. The clincal diagnostic applications of this system are described in this study.
