Trial Confirms RT Survival Benefit With ADT in Prostate Cancer

February 17, 2015
Anna Azvolinsky
Anna Azvolinsky

An 8-year analysis confirmed that adding radiotherapy to androgen deprivation therapy in prostate cancer improved patient overall survival by more than a year.

An 8-year analysis confirmed that adding radiotherapy to androgen deprivation therapy (ADT) in men with locally advanced prostate cancer improved overall survival and reduced the risk of prostate cancer–specific death. The median overall survival was 10.9 years in the combination arm compared with 9.7 years in the ADT-alone arm.

This final analysis is published in the Journal of Clinical Oncology.

The original results of this international NCIC Clinical Trials Group PR.3 trial were published in the Lancet  in 2011. This prior interim analysis showed a significant improvement in overall survival for those in the ADT plus radiotherapy treatment arm (hazard ratio [HR] = 0.77; P = .033). Based on the results, radiotherapy was recommended as part of the standard therapy for prostate cancer.

The NCIC trial is the largest study investigating the addition of radiotherapy to ADT.

The study randomized 1,205 patients enrolled in the study between 1995 and 2005 to either ADT or ADT plus radiotherapy. The median age of patients was 70. Eighty-seven percent of patients had locally advanced (T3-4) disease and 18% had tumors with a Gleason score greater than 8. Patients received a radiotherapy dose between 64 and 69 Gy in 35 to 39 fractions to the prostate and pelvis, or prostate alone.

After an 8-year median follow-up, a total of 199 men died from prostate cancer; 465 patients died in total.  

The 10-year disease progression-free rate was 46% in the ADT-alone arm compared with 74% in the ADT plus radiotherapy arm.

The most frequent grade 3 or higher treatment-related adverse events in the ADT and combination therapy arms, respectively, were impotence (29% vs 33%), hot flushes (8% vs 5%), urinary frequency (4% vs 7%), ischemia (3%  vs 5%), and hypertension (3% vs 4%). There were no differences in cardiovascular toxicities between the two therapy arms. Bowel-related adverse events were more frequent in the combination therapy arm but most were low-grade.

“It is noteworthy that the grade 3 toxicity that we detected was short term only, and we would suggest that the toxicity of radiotherapy should not be regarded as a barrier to its routine use in this patient population,” state the authors in their discussion.

The improvement in overall survival was “achieved without major detriment in terms of long-term toxicity,” concluded Malcolm D. Mason, MD, of the Cardiff University School of Medicine, in the United Kingdom.

“Although there are undoubtedly patients for whom radiotherapy or indeed any curative therapy would be inappropriate because of age, comorbidity, or other factors, we conclude that patients with clinically node-negative, locally advanced prostate cancer who are suitable for additional radiotherapy should be offered that option, an opinion shared by European and North American guidelines,” state the authors.

Further questions that remain to be addressed including whether dose escalation of radiotherapy will improve outcomes and the optimum field of radiotherapy.