Five years after having proton therapy for early- and intermediate-risk prostate cancer, 99 percent of men are living cancer-free and with excellent quality of life, according to a University of Florida Proton Therapy Institute study. Three-quarters of those with high-risk prostate cancer are also disease-free.
The study, published in the International Journal of Radiation Oncology Biology Physics, adds to the body of evidence pointing to a significant role for proton therapy in the effective and efficient treatment of prostate cancer, said Nancy P. Mendenhall, M.D., lead author and medical director of the UF Proton Therapy Institute.
"These proton therapy results compare very favorably with IMRT results, particularly for intermediate risk-disease, where disease control rates of 70 percent to 85 percent are typical," said Mendenhall, the associate chair of the UF College of Medicine department of radiation oncology. IMRT is intensity modulated radiation therapy, a form of radiation that uses photons, or X-rays, to deliver radiation. Proton therapy uses protons, particles of an atom, to deliver radiation.
The study tracked 211 patients who participated in prospective Institutional Review Board-approved trials. In each track, patients were given proton therapy over an eight-week period, a shorter interval than typical with IMRT, which may last nine to nine-and-a-half weeks. Researchers used standardized data-gathering methods for both physician-reported and patient-reported outcomes.
Physician-reported data show cancer-free survival rates at five years for low-, intermediate-, and high-risk patients are 99 percent, 99 percent and 76 percent, respectively, while overall survival rates are 93 percent, 88 percent and 90 percent.
Moreover, the rate of serious gastrointestinal and urologic complications is low, at 1.4 percent and 5.3 percent respectively for all patients. Patients also reported good outcomes with respect to both urologic and bowel function.