Men with intermediate risk, localized prostate cancer can be treated effectively with fewer and higher doses of stereotactic body radiation therapy (SBRT) over five treatment sessions, according to research presented at the American Society for Radiation Oncology (ASTRO) annual meeting.
The findings could make the healthcare system more efficient, said lead researcher Nicholas van As, MD, of the Royal Marsden NHS Foundation Trust and the Institute of Cancer Research in London in an ASTRO statement.
"Standard radiation treatment is already highly effective and is very well tolerated in people with localized prostate cancer,” he said. "But for a healthcare system and for patients to have this treatment delivered just as effectively in five days as opposed to four weeks has huge implications."
Prostate cancer is one of the most commonly diagnosed cancer in the U.S., van As noted. Most of these cancers are diagnosed before they have spread beyond the prostate gland; primary treatment options include active surveillance, radiation therapy, or prostactetomy. The typical radiation therapy protocol consists of daily doses over 20 days, while SBRT is administered in five outpatient treatments or less.
The investigators conducted a study called Prostate Advances in Comparative Evidence (PACE B) that included 874 participants across the U.K. and Canada who underwent radiation treatment. Patients were randomized into an SBRT group (443) that had five radiation doses over one to two weeks (a total dose of 36.25 Gy) or a standard radiation group (441) that received 39 doses over 7.5 weeks (78 Gy) or 20 doses over four weeks (62 Gy).
The researchers found that, at five-year follow-up, patients treated with SBRT had a similar biochemical failure-event free rate as those treated with conventional radiation, at 96% versus 95%. Side effects were not significantly different between the two groups, at 5.5% (SBRT) and 3.2% (conventional protocol).
The research suggests that men at intermediate risk prostate cancer can be offered the option of SBRT as an alternative to longer courses of radiation or prostate surgery, van As concluded.
"To be able to sit with a patient and say, 'We can treat you with a low toxicity treatment in five days, and your chance of keeping the cancer at bay for five years is 96%' – it's a positive conversation to have," he said.
