In the recently published Androgen Suppression Combined with Elective Nodal and Dose Escalated Radiation Therapy (ASCENDE-RT) Trial, combined external beam radiation therapy and low-dose rate brachytherapy prostate boost (EB-LDR) improved biochemical control compared to external beam prostate boost (EBRT), but caused greater physician reported toxicity. In this abstract, for the reasons listed above, the authors compare patient reported outcomes between EB-LDR and EBRT to inform treatment selection.
The Comparative Effectiveness Analysis of Surgery and Radiation (CEASAR) trial is a prospective population-based cohort study of men with localized prostate cancer (age <80, diagnosed between 2011 and 2012, PSA < 50). Though they have previously published their results comparing other treatment modalities, in this abstract they focus on comparing EBRT and EB-LDR. The primary outcome measure was patient-reported function measured on the 26-item Expanded Prostate Cancer Index Composite (EPIC)-26 at 6, 12 and 36 months after treatment. They focused on 5 specific components: urinary irritative, urinary incontinence, bowel, sexual and hormonal function.
Of the entire CEASAR cohort, they identified 578 men who underwent EBRT and 109 who underwent EB-LDR. Unfortunately, no specific demographics were provided. After adjusting for covariates (including use of hormonal therapy), patients undergoing EB-LDR had worse urinary irritative domain scores than EBRT at 6 months (-14.3 points, p <0.001) through 3 years (-4.6 points, p=0.03). Patients undergoing EB-LDR had worse bowel function domain scores than EBRT at 1 year only (-5.7 points, p = 0.002). Men undergoing EB-LDR had lower urinary incontinence domain scores (-4.6 points, p=0.04) than EBRT at one year, but was not maintained through three years. Men undergoing EB-LDR had significantly higher odds of having a moderate to severe problem with dysuria compared to EBRT at 6 months through three years after treatment (OR 4.6, 5.2 respectively; p<0.01). There were no significant differences in sexual function or hormonal function scores between the treatment groups at 3 years.
Based on this, the authors note that EB-LDR was associated with a significant and sustained worsening of urinary irritative symptoms compared to EBRT after three years, and some shorter term effects on bowel function and urinary continence and dysuria. As such, any potential oncologic benefit from EBLDR should be weighed against the increased toxicity from treatment. These findings may help facilitate shared decision making for different radiotherapy treatment options for localized prostate cancer and improve understanding of the comparative harms from radiation treatment.
Presented by: Daniel J. Lee, MD
Co-Authors: Zhiguo Zhao, Li-Ching Huang, Tatsuki Koyama Tatsuki, Matthew Resnick Matthew, David Penson, Daniel Barocas, and Karen Hoffman
Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, twitter: @tchandra_uromd at the 18th Annual Meeting of the Society of Urologic Oncology, November 20-December 1, 2017 – Washington, DC