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Prostate cancer: Intermittent adjuvant ADT schedule fails to demonstrate noninferiority

Key clinical point: In patients with locally advanced prostate cancer, intermittent adjuvant androgen deprivation therapy (ADT) does not show noninferiority to continuous long-term ADT in terms of modified biochemical recurrence-free survival (bRFS).

Major finding: Five-year modified bRFS rates were 84.8% in the long-term group and 82.8% in the intermittent ADT group (hazard ratio [HR], 1.13; 95% confidence interval, 0.74-1.72). Cancer-specific survival (HR, 1.150; P = .8167) and 5-year overall survival rates (93.7% vs. 90.5%; HR, 1.204; P = .5138) did not differ between groups despite more than 4 years of lower total ADT duration with intermittent therapy.

Study details: This multicenter, randomized, phase 3 trial included 280 patients with locally advanced prostate cancer treated with neoadjuvant ADT followed by radiotherapy + adjuvant ADT (long term or intermittent). Median follow-up period was 8.2 years.

Disclosures: This study was funded by a Grant-in-Aid for Cancer Research from the Japanese Ministry of Health, Labor, and Welfare. Some of the investigators reported receiving honoraria from multiple pharmaceutical companies.

Commentary

The optimal treatment strategy for local prostate cancer remains elusive. The optimal duration of androgen deprivation therapy (ADT) when administered with radiation has yet to be determined. ADT often causes bothersome side effects, so minimizing the time of ADT without sacrificing efficacy is of great importance. Ito et al. conducted a randomized control trial comparing continuous ADT post-radiation versus an intermittent ADT approach. All participants received 6 months neoadjuvant ADT prior to radiation and continued ADT during radiation. While the 5-year modified biochemical relapse-free survival was 84.8% in the long-term cohort versus 82.8% in the intermittent ADT cohort, this did not reach the noninferiority threshold. However, with so many potential permutations of ADT dosing, further study may yet reveal an improved approach to localized prostate cancer.

Mark Klein, MD

Citation:

Ito K et al. Cancer. 2020 Jun 23. doi: 10.1002/cncr.33034.