A Canadian scientific team led by Dr. Julia Levy and Dr. David Dolphin from the University of British Columbia has developed a new technique that fights the war against cancer tumours. The cancer is attacked by microscopic strangulation of the tumour cells so that the supply of oxygen is severed and the cells can no longer survive. This is accomplished with the use of a weapon, the laser gun, and its ammunition, a chemical called photofrin. The effective wavelength used for the laser corresponds to the red light region of the spectrum.
Triplet oxygen is the normal form of oxygen present in the air.
Photofrin complexes the oxygen and, when activated by the laser, allows an excited state of oxygen, called singlet oxygen, to be formed. The singlet oxygen is a non-discriminating oxidizing agent that takes oxygen from everything in its path and this results in suffocation of the cells. The chemical warfare begins by intravenous injection of photofrin into the patient. The photofrin selectively accumulates inside the tumour and waits for the laser gun to be strategically placed so that it has a clear shot at the tumour. The selective accumulation occurs because the light-activated molecule is carried to cells via a lipoprotein component of the blood that normally carries cholesterol to dividing cells.