ESTRO 2024 - Abstract Book

S2477

Clinical - Urology

ESTRO 2024

1965

Digital Poster

Acute toxicity after SABR to the prostate and pelvic lymph nodes for high-risk prostate cancer

Elisha T Fredman, Danielle Shemesh, Dror Limon, Assaf Moore

Davidoff Cancer Center, Radiation Oncology, Petah Tikvah, Israel

Purpose/Objective:

In this study we evaluate and report toxicity of stereotactic ablative radiotherapy (SABR) to the prostate and pelvic lymph in patients with high- and very high-risk prostate cancer.

Material/Methods:

Seventy seven patients with high- or very high-risk adenocarcinoma of the prostate were treated with SABR in 5 fractions to a dose of 40 Gy (78.9%), 37.5 Gy (1.3%) or 36.25 Gy (19.7%) to the prostate, 35 Gy to distal seminal vesicles, and 25 Gy to the lymph nodes up to the level of the aortic bifurcation. Nearly all (98%) received neoadjuvant, concurrent, and adjuvant androgen deprivation therapy for 18-24 months. 84% and 96% of patients had a hydrogel spacer and fiducials markers placed, respectively. All radiation plans were based on both CT and T2 sequence 3T-MRI simulation scans. Median follow up was 5 months (range 1-15) months. Common Terminology Criteria for Adverse Events, version 5.0, was used to evaluate toxicities.

Results:

At 3 month follow up, 8 patients (14.3%) reported having had a grade 1 gastrointestinal (GI) toxicity, persisting in 7.7% at 6 months, all of which resolved by 9 months. No grade 2 GI toxicities were reported at 3 months, though one grade 2 GI toxicity was reported at 6 months, resolved by 9 months. Grade 1 genitourinary (GU) toxicity was reported by 13 patients (23.2%) at 3 months, 11 patients at 6 months, and 6 patients by 9 months. Grade 2 GU toxicity was reported in 7 patients (12.5%) at 3 months, 3 patients (7.7%) at 6 months, all of which resolved by 9 months. One case of grade 3 GU toxicity occurred within one month of completing SABR, which resolved by 3 month follow up.

Conclusion:

SABR to the prostate and pelvic lymph nodes in patients with high- and very high-risk prostate cancer was well tolerated with acceptable rates of low-grade GI and GU toxicity. No persistent grade 3 toxicities were reported. Continued follow up is necessary to evaluate long-term safety and efficacy of this modern radiotherapy approach in high-risk patients.

Keywords: Prostate, SABR, lymph nodes