The US Food and Drug Administration granted premarket approval to Laserscope of San Jose, Calif., for use of its laser systems for photodynamic therapy, a cancer treatment that has shown promise in clinical trials. Photodynamic therapy involves injecting patients with a photosensitizing drug that is selectively absorbed by malignant tissue. A laser then destroys the fluorescing tissue without harm to surrounding healthy cells. QLT PhotoTherapeutics Inc. of Vancouver, British Columbia, Canada, developer of PHOTOFRIN, a light-activated drug given FDA approval, has worked with Laserscope on a number of clinical studies. The new therapy, approved for certain early- and late-stage lung cancers, represents an alternative approach to conventional cancer treatment. The procedure is performed on an outpatient basis.