Doctors in the United Kingdom have determined that patients suffering from cancer affecting their eye can usually avoid visual handicap, loss of the eye and spread of the disease by receiving proton beam radiation therapy, according to a new study published in the August 1, 2005 issue of the International Journal of Radiation Oncology-Biology-Physics, the official journal of ASTRO, the American Society for Therapeutic Radiology and Oncology.
The study, conducted on 349 patients in conjunction with the Liverpool Ocular Oncology Centre, set out to determine visual acuity, local tumor control, ocular retention and overall survival after patients received proton beam radiation therapy for melanoma affecting their eyes. The patients chosen were deemed unsuitable for other forms of treatment because of their tumor size and location, with 75 percent of the patients having tumors that extended to within three millimeters of the optic disk, which if affected can cause blindness. The large tumors also posed an increased risk of the tumor returning, retinal detachment and glaucoma.
Of the 346 patients who had the ability to count fingers before treatment began, 79.1 percent of them retained that ability at the five year mark. Before treatment, 212 patients had 20/40 vision, 44.8 percent were able to retain that visual acuity five years following radiation therapy. Overall survival rates based on the cancer spreading to other parts of the body was high with 90 percent of the patients able to stave off further disease when they were checked at the five year milestone.
"What is special is that these good results, similar to other studies, are achieved despite the fact that we reserve proton beam radiation therapy for patients who we feel would not do well with other methods," said Bertil Damato, M.D., Ph.D., F.R.C.Ophth., a doctor at St. Paul's Eye Unit at Royal Liverpool University Hospital in Liverpool, England. "The findings are also interesting because our proton beam has relatively sharp conformal dose characteristics, thereby enhancing its capability for avoiding critical structures, such as the optic disk."