Study: Tumors zapped by lasers

TORONTO, May 15 (UPI) -- New cancer drugs called photosensitizers, which are activated by laser light, have destroyed tumors in mice, say Canadian scientists.

The technology, photodynamic therapy, was discovered by researchers at the Ontario Cancer Institute at Princess Margaret Hospital in Toronto.

Anti-cancer drugs are given to the patient, which then congregate in tumor tissue. When the laser is turned on, the beam goes through normal tissues and activates the drugs, which produce a reactive form of oxygen that kills the cells to which they are attached.

Normal tissue surrounding the tumor, which does not contain the drugs, is spared, and since the drugs only respond to the laser, the process is completely controllable.

Although the current work was done in mice, the team is planning clinical trials in human beings in a year or two.

The report appears in Tuesday's issue of the Proceedings of the National Academy of Sciences.