3186 - Clinical Outcomes of Salvage Nodal Radiotherapy for Prostate Cancer with Prior Radiotherapy
Presenter(s)
M. A. Ansari1, K. E. Hoffman2, H. Mok3, S. J. Frank3, Q. N. Nguyen4, C. Tang3, S. E. McGuire3, L. L. Mayo2, S. J. Shah2, S. Prajapati5, D. S. Surasi6, P. Pilie7, C. Lozano3, O. Mohamad1,2, S. Choi8, and C. J. Hassanzadeh2,3; 1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 2Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Department of Genitourinary Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 4The University of Texas MD Anderson Cancer Center, Houston, TX, 5Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 6Department of Nuclear Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 7Department of Genitourinary Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 8Division of Radiation Oncology The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose/Objective(s):
Salvage nodal radiotherapy (SNRT) is a treatment option for patients with recurrent prostate cancer (PCa) who present with nodal recurrence. However, data on its safety and outcomes remain limited. We report early outcomes for patients treated with SNRT in the setting of prior RT.
Materials/Methods:
Between December 2018 to December 2024, 53 patients with a history of prior RT to the prostate fossa or intact prostate who underwent SNRT following localized, progressive nodal recurrence. SNRT was delivered by intensity-modulated radiation therapy (IMRT) or stereotactic body radiation therapy (SBRT) based on physician discretion. Baseline data, treatment details, toxicity, and outcomes were analyzed including progression-free survival which was calculated using Kaplan-Meier method. Descriptive statistics were used to summarize the findings.
Results:
The median age at the time of SNRT was 68 years (interquartile range [IQR], 63-73), with a median follow-up of 23.7 months (95% confidence interval [CI], 19.5-27.1 months). All patients were staged with nodal recurrence with PSMA PET imaging +/- pelvic MRI. A median of 2 involved lymph nodes (IQR, 1-3 nodes) were identified prior to SNRT. Of the 53 patients, 35 (66%) had undergone radical prostatectomy (RP), while 18 had not undergone RP. The median prostate-specific antigen (PSA) at initial diagnosis was 10.2 (IQR 5.3-19.7), with the majority classified as high risk (38%) or unfavorable intermediate risk (32%).
Patients received SNRT, with a median dose/fractions were 61.6Gy in 28 fractions. The majority of patients (93%, n=49) underwent full-chain nodal RT, while 4 patients (7%) received focal nodal RT (3 of whom received SBRT). Nearly all patients (98.1%, n=52) received concurrent androgen deprivation therapy (ADT) prescribed at the discretion of the treating physician with 1 patient refusing ADT. Median PFS was 26.7 months (95% CI, 24.0-29.2 months). Two patients died from non-cancer-related causes. No prostate cancer-related deaths were reported.
Acute grade 2 gastrointestinal (GI) toxicity was observed in 13.2% of patients, with diarrhea as the most common symptom, while no acute grade 2 genitourinary (GU) toxicity were reported. Late toxicities included 4% experiencing grade 2 GI toxicity and no late grade 2 GU toxicity. No grade 3 or higher toxicities were observed.
Conclusion:
SNRT is well-tolerated, with low rates of toxicity and favorable early PFS. These findings support SNRT as a viable option for PCa recurrence with longer term data needed to assess clinical outcomes. Further research investigating this strategy in order to delay initiation of next line of systemic therapy or provide a systemic therapy holiday are warranted.