Assessing the impact of brachytherapy boost and androgen deprivation therapy on survival outcomes for patients with unfavorable intermediate-risk prostate cancer patients treated with external beam radiotherapy.

Current recommendations regarding radiotherapy treatment for unfavorable intermediate-risk prostate cancer (UIR-PCa) include external beam radiotherapy (EBRT) ± brachytherapy boost (BT) ± androgen deprivation therapy (ADT). The ideal radiotherapy treatment approach for UIR-PCa has not been well-defined. We hypothesized that EBRT+BT±ADT is associated with improved overall survival (OS) relative to EBRT±ADT in men with UIR-PCa.

The National Cancer Database (NCDB) was used to retrospectively identify 32,246 men diagnosed between 2004 and 2015 with UIR-PCa who received EBRT (n = 13,265), EBRT+ADT (n = 13,123), EBRT+BT (n = 3440), or EBRT+BT+ADT (n = 2418). OS was the primary outcome. Inverse probability of treatment weighting was used to adjust for covariable imbalances and weight-adjusted multivariable analysis using Cox regression modeling was used to compare OS hazard ratios.

Median follow-up was 60 months (range: 3-168 months). EBRT+ADT correlated with improved OS relative to EBRT alone on multivariable analysis (Hazard Ratio (HR): 0.92, [95% Confidence Interval: 0.87-0.98], p = 0.005). Compared to EBRT+ADT, EBRT+BT (HR: 0.77 [0.69-0.85], p = 3 × 10-7) and EBRT+BT+ADT (HR: 0.75 [0.67-0.83], p = 6 × 10-8) were associated with improved OS. Eight-years OS for the EBRT+ADT versus EBRT+BT+ADT was 70% and 78% (p < 0.0001), which is similar to historical clinical trials (ASCENDE-RT 9-year OS: 74% vs. 78%, p = 0.29). Relative to EBRT+BT, EBRT+BT+ADT was not associated with improved OS (HR: 0.99 [0.87-1.11], p = 0.82).

In a large retrospective cohort, the addition of brachytherapy to EBRT correlated with improved survival in men with UIR-PCa. Men receiving EBRT+ADT+BT had improved OS relative to EBRT+ADT. The addition of ADT to EBRT, but not to EBRT+BT, correlated with improved OS.

Brachytherapy. 2022 May 28 [Epub ahead of print]

Neal Andruska, Temitope Agabalogun, Benjamin W Fischer-Valuck, Randall J Brenneman, Yi Huang, Hiram A Gay, Jeff M Michalski, Ruben Carmona, Brian C Baumann

Department of Radiation Oncology, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO. Electronic address: ., Department of Radiation Oncology, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO., Department of Radiation Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA., Biostatistics, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO., Department of Radiation Oncology, Sylvester Cancer Center, University of Miami, FL., Department of Radiation Oncology, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO; Department of Radiation Oncology, Abramson Cancer Center, University of Pennsylvania School of Medicine, Philadelphia, PA. Electronic address: .

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