Immediate Hormone Therapy Improves Prostate Cancer Survival

June 1, 1996

ASCO--In an EORTC study, the combination of radiotherapy and adjuvant hormonal therapy with an LHRH analog has been shown to significantly increase survival in patients with locally advanced prostate cancer, compared with radiotherapy alone.

ASCO--In an EORTC study, the combination of radiotherapy and adjuvanthormonal therapy with an LHRH analog has been shown to significantlyincrease survival in patients with locally advanced prostate cancer,compared with radiotherapy alone.

Michel Bolla, MD, of the University Joseph Fourier Grenoble, representingthe EORTC's Radiotherapy and Genitourinary Tract Cancer CooperativeGroups, presented the data at a scientific session of the AmericanSociety of Clinical Oncology meeting.

Dr. Bolla pointed out that the results, though promising, arepreliminary and need to be confirmed by longer follow-up. Medianfollow-up to date is only 33 months, he said.

In the study, 415 patients with prostate cancer classified asT1,T2 WHO grade 3 or T3,T4 with any histologic grade were randomizedto receive radiotherapy alone or radiotherapy plus the LHRH analoggoserelin (Zoladex) given at the start of radiotherapy and continuedfor 3 years.

Radiotherapy consisted of 5 weeks of treatment to the whole pelvis(up to 50 Gy in 20 fractions), followed by a boost to the prostateand seminal vesicles of 20 Gy for 2 weeks.

Goserelin, 3.6 mg, was given subcutaneously every 4 weeks. Toinhibit a transient rise of testosterone, patients also receivedthe antiandrogen cyproterone acetate for 1 month, starting atleast 1 week before the first goserelin injection.

Over one third of patients (35%) had a high Gleason score (8 to10) and at least 30% had baseline PSA levels 10-fold higher thannormal. Patients who failed when receiving radiotherapy alonewere given the option of receiving delayed hormonal therapy.

Striking Differences

The results showed a striking difference for estimated 5-yearoverall survival between patients receiving combination therapy(78%) and those in the radiotherapy alone arm (56%). Clinicaldisease-free survival was also significantly different--85% forthe hormonal treatment patients vs 44% for the radiotherapy alonegroup.

Clinically defined local control at 5 years was achieved in 95%of those on hormonal therapy, compared with 75% for patients treatedby radiotherapy alone. "The figures speak for themselves,"Dr. Bolla said.

He noted that 95% of patients were able to receive full hormonaltreatment; 21% had adverse reactions, primarily hot flushes, gynecomastia,weakness, and depression, which was likely linked to lack of potency.

The discussant, Dr. Michael Zelefsky, of Memorial Sloan-Kettering,called the study a "landmark--to my knowledge the only trialin the literature using hormonal therapy in combination with radiotherapyto demonstrate a survival benefit." However, he reiteratedDr. Bolla's caution about the preliminary nature of the data andthe short follow-up. "We need to wait longer to see if thesurvival advantage holds."

Dr. Zelefsky cited results of two other randomized trials suggestinga benefit for combined hormonal therapy and external beam radiotherapy--RTOG86-10 and RTOG 86-31--but as yet neither has shown a clear survivaladvantage.

Speaking from the audience, Dr. Mack Roach of the University ofCalifornia, San Francisco, noted that RTOG 86-31 is showing atrend for improvement in survival in patients with high-gradedisease, which would support the European findings.