National patterns of brachytherapy boost use for intermediate- and high-risk prostate cancer: Bridging the gap between evidence and practice.

BACKGROUND

Brachytherapy boost in combination with external beam radiation therapy (EBRT-BT) improves biochemical progression-free survival in patients with intermediate- and high-risk prostate cancer. However, its adoption in routine clinical practice remains uncertain. We aimed to evaluate national trends and factors associated with the use of EBRT-BT following the publication of the ASCENDE-RT trial.

METHODS

This retrospective cohort study used data from the Surveillance, Epidemiology, and End Results (SEER) database from 2015 to 2020. We included men with intermediate- or high-risk localized prostate cancer who received EBRT with or without brachytherapy boost as their sole initial treatment. The primary outcome was receipt of brachytherapy boost. Trends in use were assessed by year of diagnosis, and multivariable logistic regression was used to identify clinical and demographic factors associated with EBRT-BT.

RESULTS

Among 507,327 men with prostate cancer, 48,777 (9.6%) met inclusion criteria. Of these, 6775 (13.9%) received EBRT-BT. Use increased modestly from 12.4% in 2015 to 14.6% in 2020 among patients with unfavorable intermediate-risk disease, and from 12.5% to 15.2% in those with high-risk disease. In multivariable analysis, use of EBRT-BT was significantly associated with younger age, higher Gleason grade group, and advanced T stage (all p < 0.001). Compared with 2015, EBRT-BT use was more likely in 2018-2020 (p < 0.05).

CONCLUSION

Despite level 1 evidence and guideline support, brachytherapy boost remains underutilized. These findings highlight a persistent gap between evidence and practice and underscore the need for strategies to expand access to EBRT-BT and promote its use where clinically appropriate.