Shorter duration of androgen deprivation therapy reduces side effects in prostate cancer

Abdenour Nabid

CHICAGO – Reducing the duration of androgen deprivation therapy from 36 to 18 months improved quality of life without affecting survival outcomes among men with high-risk prostate cancer, according to findings presented at the ASCO Annual Meeting.

“Long-term ADT combined with radiotherapy is a standard treatment for patients with high-risk prostate cancer,” the researchers wrote. “However, the optimal duration of ADT is not yet defined.”

The combination of ADT and radiotherapy has the potential to be curative, but the side effects of ADT – which include hot flashes as well as cognitive and emotional issues – make the 36-month duration of therapy difficult for some patients, according to Heather H. Cheng, MD, PhD, assistant professor at the University of Washington School of Medicine, assistant member of the clinical research division at Fred Hutchinson Cancer Research Center and director of the Seattle Cancer Care Alliance Prostate Cancer Genetics Clinic.

“I have patients who are quite debilitated by the side effects, but they’re still trying to achieve the positive outcomes associated with this therapy,” she said. “It really becomes a balance between the toxicities and the benefits of this treatment.”

Abdenour Nabid , MD , of the Centre Hospitalier Régional Universitaire in Quebec, Canada, and colleagues assessed the outcomes associated with radiotherapy and either 36 or 18 months of ADT in a randomized phase 3 trial. The researchers randomly assigned 630 patients to receive pelvic and prostate radiotherapy in combination with 36 months (arm 1; n = 310) or 18 months (arm 2; n = 320) of ADT. OS and quality of life served as primary endpoints.

Median follow-up was 9.4 years, at which point 290 patients had died (147 in arm 1 vs. 143 in arm 2). The 10-year OS was 62.4% (95% CI, 56.4%-67.8%) in arm 1 compared with 62% (95% CI, 56.1%-67.3%) in arm 2 (P = .8412); the global HR was 1.024 (95% CI, 0.813-1.289; P = .8411).

The quality of life analysis revealed a difference in six scales and 13 items, indicating a preference for 18 months of ADT (P < .001). Two of the items demonstrated a “clinically relevant difference” in mean scores of 10 or more points, according to the study results.

“The OS outcomes were equivalent between the two arms,” Cheng said. “However, quality of life appears to be better with 18 months of ADT compared with 36 months, and long-term side effects improved as well. Eighteen months is half the standard amount of time for this therapy. That’s a big difference, especially for patients who experience severe side effects.”

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The results from Nabid and colleagues should provide clinicians with “more confidence” in recommending the shorter duration of ADT, Cheng continued.

“We now have data to support the belief that you aren’t minimizing your chance of cure with the shorter duration of therapy. There are never any guarantees, but the likelihood of cure is not significantly diminished by reducing the length of hormone therapy,” she said. “This phase 3, randomized clinical trial will likely to represent level one evidence.”

ADT used in combination with radiotherapy “can be safely reduced from 36 to 18 months without compromising outcomes or quality of life,” the researchers wrote. “Eighteen months of ADT represents a new standard of care in high-risk prostate cancer.” – by Julia Ernst, MS

Reference:

Nabid A, et al. Abstract 5008. Presented at: ASCO Annual Meeting; June 2-6, 2017; Chicago.

Disclosures: Nabid reports that he serves as a consultant or advisor to Astellas Pharma, Bayer, Janssen Oncology and Sanofi Canada and on the speakers bureau for Janssen Oncology and Sanofi Canada; he also reports that he receives travel, accommodations and expenses from Sanofi Canada. The study was funded by AstraZeneca Pharmaceuticals. Cheng reports no relevant financial disclosures.