A secondary analysis of the historic RTOG 92-02 prostate cancer trial examined results of men with intermediate-risk prostate cancer who had received long-term hormonal therapy after radiation therapy. Based on the additional analysis, researchers concluded that there were no additional benefits of this treatment when compared to short-term hormonal therapy. The study results were presented today at the American Society for Radiation Oncology’s (ASTRO’s) 55th Annual Meeting, held in Atlanta, Ga, September, 22 – 25, 2013.
Men with advanced prostate cancer typically receive hormonal therapy to reduce the level of androgens, or male hormones, in their bodies. Although hormone therapy alone will not cure prostate cancer, lowering androgen levels can reduce prostate tumors size or stall their growth.
Potential benefits
Results of the original RTOG 92-02 trial, published in 2003, showed the potential benefits of long-term adjuvant androgen deprivation (LTAD) for two years after initial androgen deprivation, when compared to short-term (initial) androgen therapy (STAD) in mostly high-risk prostate cancer patients receiving external beam radiation therapy (EBRT).[1]
…. data supports administering less treatment, which will result in fewer side effects and reduce patients’ overall health care costs
The RTOG 92-02 study demonstrated a benefit in all study endpoints except OS, with the exception of the subset of patients with Gleason score 8-10. More recently, another study, RTOG 94-08 found an OS advantage in patients with T1b-T2b prostate CA with PSA less than 20, with the bulk of the benefit observed among intermediate risk patients. However, while STAD was validated in 94-08, it is not known whether patients in the intermediate risk subset would experience an additional survival benefit with longer duration androgen deprivation.
Additional survival benefit with LTAD
Because some intermediate-risk prostate cancer patients were included in the initial RTOG 94-08 study, the current analysis was conducted to determine if patients in the intermediate-risk subset experienced an additional survival benefit with LTAD.[2] Furthermore, the inclusion of some intermediate risk patients in the RTOG 92-02 study allowed the researchers to explore whether LTAD had any incremental benefit above STAD.
The researchers reviewed all patients enrolled in RTOG 92-02 categorized with intermediate-risk prostate cancer with T2 disease (tumor confined to the prostate), a Prostate Specific Antigen (PSA) of < 10 and a Gleason Score of 7; or, who were immediate-risk prostate cancer patients with T2 disease, PSA of 10-20 and a Gleason Score < 7.
Additional analysis
A total of 133 patients were analyzed. The LTAD group consisted of 59 patients, and the STAD group consisted of 74 patients. Statistical analysis was used to determine Overall Survival (OS), Disease Specific Survival (DSS) and PSA Failure rates (PSAF), and the median follow-up was more than 11 years. There was no statistical difference in OS with 10-year estimates of 61% for the STAD group and 65% for the LTAD group. DSS was found to be 96% in both groups. PSAF occurred in 38 patients in the STAD group and in 33 in the LTAD group. Ten-year PSAF rates were 53 percent for the STAD group and 55% for the LTAD group (p=.99).
Is more beter?
The result of the secondary analyses showed that LTAD did not confer a benefit. “Most clinicians have felt that ‘more was better’ when it came to blocking testosterone in prostate cancer patients, however, results for the specific endpoints we focused on, OS and DSS, indicate that this was clearly not the case,” said Amin Mirhadi, MD, lead author of the study and a radiation oncologist at Cedars-Sinai Medical Center in Los Angeles. “This data supports administering less treatment, which will result in fewer side effects and reduce patients’ overall health care costs.”
For more information:
Abstract: 61
Authors: Mirhadi AH, Hunt D, Hanks GE, Peters CA, Zeitzer KL, D’Souza DP, Lawton CA, Sandler HM et al.
Title: Effect of Long-Term Hormonal Therapy (vs. Short-Term Hormonal Therapy): A Secondary Analysis of Intermediate Risk Prostate Cancer Patients Treated on RTOG 9202
Monday: September 23, 2013
Time: 10:45 a.m. EST
References:
[1] Hanks GE, Pajak TF, Porter A, Grignon D, Brereton H, Venkatesan V, Horwitz EM, Lawton C, Rosenthal SA, Sandler HM, Shipley WU;
Phase III trial of long-term adjuvant androgen deprivation after neoadjuvant hormonal cytoreduction and radiotherapy in locally advanced carcinoma of the prostate: the Radiation Therapy Oncology Group Protocol 92-02. J Clin Oncol. 2003 Nov 1;21(21):3972-8.[Article][PubMed]
[2] Jones CU, Hunt D, McGowan DG, Amin MB, Chetner MP, Bruner DW, Leibenhaut MH, et al. Radiotherapy and short-term androgen deprivation for localized prostate cancer. N Engl J Med. 2011 Jul 14;365(2):107-18. doi: 10.1056/NEJMoa1012348.[Article][PubMed]
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