Prostate Cancer Combo Therapy May Not Be One Size Fits All

September 23, 2015
Anna Azvolinsky

Six months of radiation therapy combined with ADT for prostate cancer may not produce a survival benefit in men with moderate to severe comorbidities.

Six months of radiation therapy combined with androgen deprivation therapy (ADT) for prostate cancer may not produce a survival benefit in men with moderate to severe comorbidities. These results, a follow-up analysis of a randomized trial of 206 patients with unfavorable-risk prostate cancer, suggest it is important to assess the comorbidities of prostate cancer patients in order to choose an optimal therapy. The analysis is published in JAMA.

After a median follow-up of 16.62 years, the researchers found no difference in survival between the two main treatment groups (radiation therapy vs the combination of radiation plus ADT). The estimated 15-year overall survival rate was 27.58% in the radiation therapy group and 35.47% in the combination group (P = .22).

But in men with moderate to severe comorbidities (n = 49), the estimated 15-year overall survival rate was 20% with radiation therapy alone compared with 8.33% with the combination therapy (P = .07). Radiation therapy alone in these patients was also linked with decreased overall mortality (hazard ratio [HR], 0.36; P = .001) and decreased cardiac mortality (HR, 0.17; P < .001).

By contrast, in men with no or minimal comorbidities, the estimated 15-year overall survival rate was 30.52% and 43.77% in the radiation therapy and combination therapy arms, respectively (P = .04).

The clinical trial results were originally published in JAMA in 2008. The original publication showed that after a median follow-up of 7.6 years, men treated with radiation therapy alone had an increased risk of all-cause mortality compared with men treated with the combination (HR, 1.8; P = .01). But, the benefit of the combination treatment appeared to be among men with minimal comorbidities.

Limitations of the new study included a post-randomization analysis, which is only hypothesis-generating, and low event rates, noted study author Anthony V. D’Amico, MD, PhD, of Brigham and Women’s Hospital in Boston, and colleagues, who also conducted the original trial. “Nevertheless, the association of treatment with radiotherapy alone with decreased cardiac and overall mortality in men with moderate or severe comorbidity suggests that administering ADT to treat unfavorable-risk prostate cancer in these men should be carefully considered,” wrote the authors in their discussion.