Tumor Fluorescence with Hematoporphyrin Derivative

Abstract

Hematoporphyrin derivative (HpD) is one of several photodynamically active dyes that accumulate in tumor cells and can be used to differentiate neoplastic from normal tissue by violet light activation. Degree of tumor fluorescence was studied in relation to the nature of the hematoporphyrin compound, dose of HpD injected, route of injection, and intensity of activating light. Our studies indicate that HpD is not a chromatographically homogeneous material. Four components of HpD have been identified by thin-layer chromatography; their nature is not presently known. Pure HpD is the best agent for tumor fluorescence as compared with the components studied. Intravenous injection of HpD resulted in a more intense red-orange fluorescence than that after intraperitoneal injection. Fluorescence was more intense at the tumor periphery where tumor invaded normal tissues and around blood vessels. HpD injection of 0.002 mg/gm body weight induced more selective fluorescence of tumor than did 0.01 mg/gm. Microscopic examination of tumor showed fluorescence distributed throughout the cytoplasm. A fiberoptic bronchoscope attached to the Mayo-Baldes activating light source made possible induction of slight tumor fluorescence, but the intensity of activating light would not be adequate for clinical examination of the bronchial tree and detection of tumor.