Hematoporphyrin Photomedicine of Cancer

The concentration of porphyrins by malignant tissue has been known for decades and has been thoroughly reviewed in several recent symposium volumes.1–3 From these symposia as well as the many articles published in refereed journals, a picture emerges that is both positive and negative. On the positive side it has been demonstrated that (1) some porphyrins are concentrated selectively in malignant tumors in animals and man; (2) the concentrated porphyrins can be detected by fluorescence emission, thus facilitating identification of malignancy; (3) the concentrated porphyrins will absorb light of particular wavelengths, leading to a photochemical destruction of the tumor; and (4) in some human cases, localized tumors have been eradicated by this method with no regrowth detected for up to 2 years.