Short-term as good as long-term hormonal therapy

September 30, 2013

Short-term hormone therapy appears to produce outcomes that are as favorable as those for long-term therapy in men with intermediate-risk prostate cancer, according to the results of two studies from the Radiation Therapy Oncology Group.

Short-term hormone therapy appears to produce outcomes that are as favorable as those for long-term therapy in men with intermediate-risk prostate cancer, according to the results of two studies from the Radiation Therapy Oncology Group (RTOG).

RTOG 9910, the larger of the two studies, confirmed a disease-specific-survival rate of 95% when patients received fewer weeks of neoadjuvant total androgen suppression prior to radiation therapy. In a secondary analysis of RTOG 9202, men who had received long-term hormonal therapy after radiation therapy showed no additional benefits when compared to short-term hormonal therapy. Results of both studies were reported at the American Society for Radiation Oncology annual meeting in Atlanta.

The phase III trial RTOG 9910 evaluated 1,490 intermediate-risk prostate cancer patients (mean age, 71 years at accrual) from 152 North American institutions. Patients were followed for an average of 9 years. They were stratified and randomized into two groups: those who received 8 weeks of neoadjuvant total androgen suppression (Group 1) and those who received 28 weeks of neoadjuvant total androgen suppression (Group 2). Both groups then received 8 weeks of external beam radiation therapy and concurrent androgen suppression.

There were 30 prostate cancer deaths in Group 1, for a 10-year disease-specific survival rate of 95%, and 24 prostate cancer deaths in Group 2, for a 10-year disease-specific survival rate of 96% (no statistical difference). The 10-year overall survival rate was 66% in Group 1 and 67% in Group 2.

Hot flashes and erectile dysfunction were more common in Group 2.

“Overall, both groups had very, very good outcomes, but patients assigned to Group 2 had more side effects from androgen suppression than Group 1, who received only 8 weeks of neoadjuvant total androgen suppression,” said lead author Thomas Pisansky, MD, of the Mayo Clinic in Rochester, MN. “Now, investigators know the upper boundary of how much androgen suppression is needed in this group of patients.”

In the second study, researchers reviewed all patients enrolled in RTOG 9202 categorized with intermediate-risk prostate cancer with T2 disease, PSA <10.0 ng/mL, and a Gleason score of 7; or, who were immediate-risk prostate cancer patients with T2 disease, PSA of 10.0-20.0 ng/mL, and a Gleason score <7. A long-term adjuvant androgen deprivation group consisted of 59 patients, and a short-term therapy group consisted of 74 patients.

There was no statistical difference in overall survival, with 10-year estimates of 61% for the short-term group and 65% for the long-term group. Disease-specific survival was 96% in both groups. Ten-year PSA failure rates were 53% and 55% in the short- long-term groups, respectively (p=.99).

“This data supports administering less treatment, which will result in fewer side effects and reduce patients’ overall health care costs,” said lead author Amin Mirhadi, MD, of Cedars-Sinai Medical Center in Los Angeles.

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