Complete remissions of early stage human lung and bladder cancers have been obtained with an experimental form of therapy called photoradiation therapy (PRT).
Researchers presenting the studies at the XIII International Cancer Conference in Seattle were enthusiastic about the treatment, entailing use of a photosensitizing agent activated by exposure to visible light. A dozen hospitals in the United States are already using this technique, and as many more are gearing up to do so.
But some investigators caution that results are still preliminary and that the treatment seems applicable only to a limited number of patients.
The key to the therapy is hematoporphyrin derivative (HpD), which "seems to have most of the qualities we want in a photosensitizing agent to treat cancer," according to Thomas J. Dougherty, PhD, of Roswell Park Memorial Institute in Buffalo, who has pioneered the development of the HpD system (JAMA [MEDICAL NEWS] 1979;242:403).