Genitourinary Cancer

PV QA 1 - Poster Viewing Q&A 1

SU_30_2303 - Variations in Patterns of Concurrent Androgen Deprivation Therapy (ADT) Use Based on Standard Dose Versus Dose-Escalated Radiation Therapy (DE RT) for Prostate Cancer

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Variations in Patterns of Concurrent Androgen Deprivation Therapy (ADT) Use Based on Standard Dose Versus Dose-Escalated Radiation Therapy (DE RT) for Prostate Cancer
J. J. Mohiuddin1, V. Narayan2, S. Venigalla1, and N. Vapiwala1; 1Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 2Division of Hematology Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA

Title: Variations in patterns of concurrent androgen deprivation therapy (ADT) use based on standard dose vs. dose-escalated radiotherapy (DE RT) for prostate cancer

Purpose/Objective(s): Multiple trials have established a survival benefit with the addition of ADT to standard dose external beam RT (EBRT) for patients (pts) with intermediate (IR) and high-risk (HR) prostate cancer (PC). The advent of DE RT in PC (total dose >75.59 Gy per NCCN guidelines) has prompted some to question whether more intense local therapy can obviate the need for micrometastasis-directed systemic therapy. Although subgroup analysis of EORTC 22991 demonstrated a progression-free survival benefit with ADT even in pts receiving DE-EBRT, the trial did not include pts who received DE RT via EBRT plus a brachytherapy boost (EBRT-BB). Given the ongoing debate of RT dose vs. ADT, we hypothesized that the proportion of pts receiving concurrent ADT would be lower among those receiving EBRT-BB vs. DE-EBRT.

Materials/Methods: Men with favorable/unfavorable IR (FIR/UIR) and HR PC treated with definitive RT from 2004-2015 were identified using the National Cancer Data Base. Pts who underwent extreme hypofractionation (i.e. SBRT) were excluded. DE-EBRT was defined as >75.59 Gy. An additional “favorable” HR subgroup (FHR, see table) was created to examine practice patterns for cases often considered resectable by urologists. Contingency tables and a logistic regression (LR) were created to measure associations and adjust for confounders (e.g. age, facility volume, comorbidities, year, etc).  

Results: 120,277 men were included. The rate of ADT receipt in the UIR and FHR groups differed based on DE-EBRT vs. EBRT-BB. This difference held for both the older (UIR 8.4% absolute difference, FHR 12.1%) and more recent time periods (UIR 13.4% absolute difference, FHR 11.7%). In a multivariable LR, pts who underwent EBRT-BB were less likely to receive concurrent ADT compared to those who had DE-EBRT (odds ratio 0.76, 95% confidence interval 0.74 to 0.79). The interaction test between type of dose escalation (DE-EBRT vs. EBRT-BB) and risk group was significant at the p <0.0001 level.

Conclusion: Patients with unfavorable intermediate and favorable high risk PC are less likely to receive concurrent ADT if they are dose escalated with a brachytherapy boost compared to EBRT alone. We await the results of RTOG 0815 to guide whether it is clinically sound to omit ADT for patients receiving EBRT with a brachytherapy boost.  
    Favorable Intermediate N=32,202 Unfavorable Intermediate N=34,457   “Favorable High” (Low volume GS8, T1c,    PSA <=20) N=6,777 All Other High N=46,841
2004-2011 N=81,958 Not dose escalated   41.5 59.7 76.4 80.4
EBRT >75.59 Gy   35.1 56.6 77.7 81.3
EBRT with brachytherapy boost   38.1 48.2 65.6 74.0
2012-2015 N= 38,319 Not dose escalated   25.8 57.2 78.8 85.5
EBRT >75.59 Gy   30.3 56.1 82.3 87.3
EBRT with brachytherapy boost   24.3 42.7 70.6 84.0
Table: % of patients receiving concurrent ADT stratified by year of diagnosis, level of dose escalation, and risk group  

Author Disclosure: J.J. Mohiuddin: None. V. Narayan: None. S. Venigalla: None. N. Vapiwala: Vice Chair; ACGME Residency Review Committee. President; ADROP.

Send Email for Jahan Mohiuddin


Assets

SU_30_2303 - Variations in Patterns of Concurrent Androgen Deprivation Therapy (ADT) Use Based on Standard Dose Versus Dose-Escalated Radiation Therapy (DE RT) for Prostate Cancer



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Variations in Patterns of Concurrent Androgen Deprivation Therapy (ADT) Use Based on Standard Dose Versus Dose-Escalated Radiation Therapy (DE RT) for Prostate Cancer