Between 1995 and 2005, 1,205 men were randomly assigned to receive ADT plus radiation or ADT alone. Most of the men had stage T3/T4 disease. After a median follow-up of 6 years, 51 of the 603 men who received the combined modality therapy had died, compared with 89 of the 602 men who received ADT alone. Fewer than 2 percent of patients in either group experienced significant gastrointestinal toxicities. However, patients receiving radiation had more low-grade diarrhea and rectal bleeding.
“These results suggest that adding radiation therapy to the treatment plan for these patients could become part of standard therapy and should be considered,” said lead researcher Padraig R. Warde, M.D., of Princess Margaret Hospital and the University of Toronto.
The researchers projected that fewer men who received ADT plus radiation would die from their prostate cancer over 10 years than would men who received ADT alone (15 percent versus 23 percent). Final results are expected in the next few years.
Known as Intergroup T-94-0110, the study was coordinated by the National Cancer Institute of Canada with participation by the Medical Research Council of the United Kingdom and the Southwest Oncology Group in the United States. Although the study was originally designed in 1993, “we believe the results are still relevant in 2010,” said Dr. Warde. “Close to 50 percent of patients with high-risk disease are [still] managed with ADT alone.” In fact, he said, the benefit of adding radiation may be underestimated because changes in technology over the last decade have enabled oncologists to deliver “much higher doses of radiation into the prostate than used in this study.”