Clinical research led by radiation oncologists at the Princess Margaret Hospital (PMH) Cancer Program, University Health Network showed men with locally advanced or high-risk prostate cancer who receive combined radiation and hormone therapy live longer and are less likely to die from their disease.
The findings are published online today in The Lancet
(doi: 10.1016/S0140-6736(11)61095-7). Principal investigator Padraig Warde, deputy head, PMH radiation medicine program, says: "The study shows combining radiation and hormone therapy improves overall survival by 23 percent and disease-specific survival by 43 percent, compared with treating with hormone therapy alone.
"Based on these results, we believe adding radiation to the treatment plan should become part of the standard therapy." Dr. Warde is also a Professor in the Department of Radiation Oncology, University of Toronto. (view Dr. Warde video at http://www.youtube.com/watch?v=tC0uJWcrGJg
Prostate cancer is the most common malignancy in men and between 15% and 25% percent of cases are high risk, says Dr. Warde. The Canadian Cancer Society estimates 25,500 new cases will be diagnosed this year and that 4,100 men will die from the disease.
In the randomized study of 1,205 men to investigate appropriate treatment for high-risk prostate cancer, half the participants received androgen deprivation therapy ("hormone therapy") alone and half received hormone therapy plus radiation.
After seven years, 66 percent of men who had hormone therapy only were still alive, compared with 74 percent who received the combined therapy. Among those in the hormone-only group, 26 percent died from their prostate cancer versus 10 percent who received hormone therapy plus radiation.
"This study will challenge the prevailing dogma of only using hormone therapy alone for locally advanced prostate cancer," says Dr. Warde. "As well, we found the radiation therapy was tolerated well with no significant toxicity."
He believes the benefits of combined therapy could actually be even greater now given the use of more targeted radiation techniques that have been developed since the study began in 1995.
"Our study shows the way to combine existing, effective treatment options that are readily available to improve outcomes for many men with high-risk prostate cancer."
The study, conducted by the NCIC Clinical Trials Group (NCIC CTG) at Queen's University in Kingston, Ontario in collaboration with the Medical Research Council UK involved clinical researchers and staff from participating sites throughout Canada and internationally. Patients were enrolled onto the study between 1995 and 2005.