For men with locally advanced prostate cancer, adding radiation therapy to hormone therapy decreased the risk of dying from prostate cancer by 43% compared with the use of hormone therapy alone, according to a Phase III study (Abstract CRA 4504), reported at the ASCO Annual Meeting at an oral session.
“This study will challenge the prevailing dogma of only using hormone therapy for locally advanced prostate cancer,” said lead author Padraig Warde, MBChB, Deputy Head of the Radiation Medicine Program at Princess Margaret Hospital at the University of Toronto Princess Margaret Hospital.
“We found that men who received the combination lived longer, and were less likely to die of their prostate cancer compared with those who had only hormone therapy.
“These results suggest that adding radiation therapy to the treatment plan for these patients could become part of standard therapy and should be considered.”
Dr. Warde explained in a news release that although some physicians and clinical guidelines recommend radiation with androgen-deprivation therapy as a treatment option for patients with locally advanced prostate cancer, it has not been clear whether that alone was sufficient therapy for these patients, and whether the side effects of radiation could be avoided.
In this study, men with locally advanced or high-risk prostate cancer were randomly assigned to receive androgen-deprivation therapy alone (602 patients) or with radiation (603 patients). After seven years, 66% of those in the first group, receiving the hormone therapy without radiation therapy were still alive, compared with 74% of those who had the added radiation therapy.
Similarly, among those in the hormone therapy-only group, 26% died of their prostate cancer compared with 10% of those who received the added radiation therapy, and the survival time was also six months longer for those who received radiation.
There was no increase in significant, long-term gastrointestinal toxicity between treatment groups, Dr. Warde reported.
He and his colleagues projected that fewer men who received androgen-deprivation plus radiation would die of their prostate cancer over 10 years (10-year cumulative disease specific death rate of 15%) compared with 23% for patients receiving hormone-therapy alone.
“In view of this data, combined- modality therapy should be the standard treatment approach for these patients,” Dr. Warde and his co-researchers concluded.
A multicenter study by researchers from France showed similar results. In that study (Abstract CRA4505), a team led by Nicolas Mottet, MD, PhD, from Clinique Mutualiste in St. Etienne, patients younger than 80 with histologically confirmed locally advanced prostate cancer were randomized to receive leuprorelin androgen-deprivation therapy either alone (130 patients) or combined with radiation (133 patients).
The five-year clinical progression-free survival rate was 89% for the combined-therapy group vs 62% for the group receiving only androgen-deprivation therapy. The cumulative incidence of loco-regional disease progression at five years was about 10% for the combined group vs 29% for patients not receiving radiation therapy, and the cumulative incidence of metastatic progression at five years was 3% vs 10.8%.
Dr. Mottet and his colleagues concluded that adding local radiotherapy to androgen-deprivation therapy with three years of LHRH significantly reduces the risk of clinical progression. “With a still limited follow-up of five years, the benefit is mainly due to locoregional control; and for distant metastases, a prolonged follow-up is needed to see a larger benefit.
“Still,” the team said, “this reduction of progression confirms that a combined modality should be the standard for patients with a significant life expectancy.”