Shorter ADT Course May Suffice for High-Risk Prostate Cancer

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A new study shows no significant difference in overall survival between 18 and 36 months of androgen deprivation therapy used in combination with radiation therapy.
A new study shows no significant difference in overall survival between 18 and 36 months of androgen deprivation therapy used in combination with radiation therapy.

Reducing the duration of androgen deprivation therapy (ADT) from 36 months to 18 months in men with localized high-risk prostate cancer (PCa) also receiving radiation therapy improves their quality of life without decreasing overall survival, according to a new study.

Investigators randomly assigned 630 men to receive pelvic and prostate radiation therapy and either 18 or 36 months of ADT (short and long arm, respectively). The 5-year overall survival (OS) rates were 86% in the short arm and 91% in a long arm, a non-significant difference, Abdenour Nabid, MD, from the Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada, and colleagues reported online ahead of print in European Urology

The investigators assessed quality of life (QoL) using EORTC (European Organisation for Research and Treatment of Cancer) validated tools: EORTC30 version 3.0, which is a 30-item score scale for global QoL, and PR25, which is more specific to prostate cancer and consists of 25 items, 6 of which assess sexual activity and sexual functioning. The investigators regrouped all 55 items into 21 scales. A QoL analysis revealed a significant difference in 6 scales and 13 items favoring the shorter course of ADT.

“We were not really surprised by the results; like many colleagues we think that 18 months is sufficient in most of these cases,” Dr Nabid told Renal & Urology News.

The short and long arms of the study included 320 and 310 patients, respectively. After a median follow-up of 9.4 years, 290 patients died, 143 in the short arm and 147 in the long arm. The median duration of ADT for all patients was 17.9 months in the short arm and 35.4 months in the long arm. The 10-year cumulative incidence of biochemical failure was 31% in the short arm compared with 25% in the long arm. In adjusted analyses, patients in the long arm had a significant 29% decreased risk of biochemical recurrence compared with those in the short arm.

Dr Nabid and his colleagues noted that 2 EORTC and 1 RTOG (Radiation Therapy Oncology Group) randomized trials have shown improvement in OS in men with high-risk PCa treated with RT and 36 months of ADT. Those trials, however, only compared 36 months of ADT with no ADT or 6 months of ADT. One trial compared 28 and 4 months of ADT.

“To my knowledge, no other study compares 36 versus 18 months of ADT in high-risk prostate cancer,” Dr Nabid said.

Neil Desai, MD, Assistant Professor of Radiation Oncology at the University of Texas Southwestern Medical Center in Dallas, said these data are important and will change clinical practice in select cases. Patients in this study better reflect those who now present in the clinic. “It gives us more flexibility to personalize treatment and update patients on outcomes in a more contemporary setting of PSA-detected high-risk disease as compared to locally advanced presentations of high-risk disease in older trials,” Dr Desai said. “The detailed data on compliance and testosterone recovery in particular can only give us a better ability to refine our therapy intensity to what a patient is on board with doing. So, yes for me it is practice changing for some of my patients.”

References

Nabid A, Carrier N, Martin AG, et al. Duration of androgen deprivation therapy in high-risk prostate cancer: A randomized phase III trial. Eur Urol. 2018; published online ahead of print.

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