3243 - Changing Landscapes of Adjuvant Radiotherapy after Prostatectomy in Prostate Cancer

12:45pm - 02:00pm PT

Hall F

Screen: 14

POSTER

Presenter(s)

Harshath Gupta, MD - MD Anderson Cancer Center, Houston, TX

H. Gupta¹, Z. El Kouzi¹, M. M. Qureshi², S. E. McGuire³, S. J. Shah¹, K. E. Hoffman³, C. Tang³, Q. N. Nguyen³, L. L. Mayo¹, H. Mok³, C. J. Hassanzadeh³, R. J. H. Park³, S. J. Frank³, S. Choi³, and O. Mohamad³; ¹Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, ²Boston University Chobanian & Avedisian School of Medicine, Boston, MA, ³Department of Genitourinary Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX

Purpose/Objective(s): The role of adjuvant radiation therapy (RT) after radical prostatectomy (RP) in prostate cancer has evolved, particularly in the context of major clinical trials shaping contemporary practice about early salvage RT vs. adjuvant RT. This study aims to evaluate national trends in adjuvant RT use over time and identify clinical and sociodemographic factors influencing treatment decisions.

Materials/Methods: We conducted a retrospective cohort analysis using the National Cancer Database to identify patients diagnosed with nonmetastatic prostate cancer who underwent RP between 2004-2022. Clinical and demographic information were obtained from electronic medical records. Descriptive statistics characterized adjuvant RT use with comparisons performed using Pearson's Chi-Square test for significance and Cramer's V for effect size. Multivariable logistic regression assessed factors associated with adjuvant RT utilization (significance threshold p<0.001). Covariables included age, race, year of diagnosis, rurality, American Joint Committee on Cancer (AJCC) stage, pathologic T (pT) and N (pN) staging, surgical margins, hormone therapy use, facility location and type, median income, education status, insurance type/status, and Charlson-Deyo Comorbidity Index.

Results: Among 867,694 nonmetastatic prostate cancer patients (median age, 62; IQR 57-67), 33,508 (3.9%) received adjuvant RT. Patients with pT2 and pT3-T4 disease comprised 67.3% and 27.5% of the cohort, respectively, while pN1 patients accounted for 3.1%. Hormonal therapy was given to 16,134 (48%) of adjuvant RT recipients. Adjuvant RT use rose from 2.5% in 2007 to 6.7% in 2018 but subsequently declined to 3.8% by 2022. Adjuvant RT was received by 3.9% of pT2 vs 11% of pT3–pT4 patients (p <0.0001, ?²; Cramer’s V 0.24), 1.7% of those with negative margins vs 11% with positive margins (p <0.0001, ?²; Cramer’s V 0.20), and 4.5% of node-negative vs 24% of node-positive patients (p <0.0001, ?²; Cramer’s V 0.20). On multivariable analysis, factors significantly associated with increased adjuvant RT utilization included positive surgical margins, pT3-pT4 disease, nodal positivity, higher AJCC Stages, higher Gleason scores, Medicare/Medicaid (vs private insurance), and non-White race. Conversely, younger age, later year of diagnosis, and treatment at academic or integrated network cancer centers (vs. community practices) was associated with lower adjuvant RT use.

Conclusion: Despite an initial increase, adjuvant RT use has declined since 2018, coinciding with major studies on adjuvant vs salvage RT (RAVES, RADICALS, GETUG-AFU 17, ARTISTIC). While adverse pathologic features and social determinants correlate with adjuvant RT use, overall utilization remains low even in higher-risk patients. These findings highlight evolving treatment patterns and potential disparities in adjuvant RT delivery.