Androgen Suppression Adjuvant to Radiotherapy in Carcinoma of the Prostate. Long Term Results of Phase III RTOG Study 85-31

Reviewer: Roberto Santiago, MD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: October 21, 2003

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Presenter: Miljenko V. Pilepich
Presenter's Affiliation: RTOG
Type of Session: Scientific

Background

    RTOG 85-31 was one of the first studies to evaluate the worth of adding androgen suppression to radiation therapy. It analyzed the effectiveness of adjuvant goserelin in patients with poor prognosis prostate cancer treated with definitive radiotherapy. Because of this, it is one of the few studies providing long-term outcome data for this approach. Obviously, long-term results are essential to draw conclusions about the effectiveness of any treatment for prostate cancer. This abstract updates the results of RTOG 85-31.

Materials and Methods

  • Elegible patients included those with T3/T4 tumors and/or lymph node involvement. It also included patients with evidence of T3 disease or positive margins of resection in the prostatectomy specimen.
  • All patients received 46 Gy to the whole pelvis with a boost to the primary tumor to 65-70 Gy (post-surgical patients were treated to a dose of 60-65 Gy).
  • Patients were randomized between no adjuvant therapy or the initiation of goserelin during the last week of radiation to be continued indefinitely or until signs of progression.
  • Patients on the radiation therapy alone arm could receive goserelin as salvage treatment for progressive disease.
  • 977 patients were entered on study. The median follow up is currently 7.6 years and 11 years for patients alive. Patient/tumor characteristics were well balance between the treatment arms: 28% had positive lymph nodes, 15% were status post surgery, 32% had GS 8-10, and 38% had GS 7.

Results

  • Patients who received hormones did better in all parameters measured. Local failure was 30% vs. 50% (p<.0001)
  • Distant metastatic rate was 25% vs. 40% (p<.0001)
  • Biologic failure free survival was 30% vs. 10% (p<.0001)
  • Prostate cancer specific survival was much better in the group treated with hormones (exact data not given) (p=.0052)
  • Absolute survival was 53% vs 38% (p=.0043)
  • On subset analysis for absolute survival there was no significant difference between the arms for patients with GS 2-6. However, there was a significant benefit to immediate androgen suppression for patients with GS 7 as well as for those with GS 8-10 disease (p=.026 and p=.0046, respectively).

Author's Conclusions

  • Adjuvant hormonal therapy in patients with prostate cancer and stage T3/4 and/or node positive and/or positive margins of resection provides a benefit in all endpoints analyzed in this trial. However, the subgroup of patients with GS 2-6 does not appear to derive a significant benefit.
  • When compared with the previous reports of this study, the benefits of immediate androgen suppression have increased over time.
  • The improvements for patients with GS 8-10 disease are substantial.

Clinical/Scientific Implications

  • This update confirms disease control and survival benefits with the early addition of androgen suppression to radiotherapy for patients with T3/4 tumors and/or lymph node involvement.
  • These benefits were also seen in patients initially managed surgically and found to have high-risk factors on the prostatectomy specimen. Therefore, radiotherapy plus adjuvant androgen ablation should remain the standard of care for these patients.
  • However, androgen ablation is not without side effects, especially when given indefinitely.
  • The high proportion of patients expected to survive into the second decade post-treatment with this approach underlines the need for long-term quality of life data.

Oncolink's ASTRO Coverage made possible by an unrestricted Educational Grant from Siemens Medical Solutions.


News
ASTRO: Combination Therapy Beneficial in Prostate Cancer

Jul 30, 2014 - Long-term survival may be increased in medium-risk prostate cancer patients who receive short-term androgen deprivation therapy before and during radiation treatment compared with men who receive radiation alone. In addition, proton beam therapy may be associated with a decreased risk of disease recurrence after 10 years and has minimal side effects after one year, according to research presented at the 51st Annual Meeting of the American Society for Radiation Oncology, held from Nov. 1 to 5 in Chicago.



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