# Real world comparison of adjuvant vs. salvage radiation therapy on cancer-control outcomes after radical prostatectomy

## TL;DR

This study compares cancer outcomes after adjuvant or salvage radiation therapy following prostatectomy and finds no significant differences in survival rates.

## Contribution

The study provides real-world evidence that adjuvant and salvage radiation therapies yield similar mid-term cancer control outcomes.

## Key findings

- Adjuvant radiation therapy patients had worse baseline tumor characteristics but similar 60-month metastasis-free survival rates compared to salvage therapy patients.
- No significant differences in cancer-specific or overall survival were observed between adjuvant and salvage radiation therapy groups.
- High-risk patient subgroups showed similar outcomes, though adjuvant therapy showed slightly higher overall survival rates.

## Abstract

Outcomes of adjuvant (aRT) or salvage radiation therapy (sRT) after radical prostatectomy are under investigation regarding cancer-control outcomes.

Relying on the University Cancer Center database elaborating differences in metastasis-free (MFS), cancer-specific (CSS) and overall survival (OS) of aRT vs. sRT-treated patients between 2014–2024. Sensitivity analyses addressed high-risk patients with pN1 and/or Gleason score 8–10 and/or pT3–4 stage.

Of 1862 patients, 7.1% underwent aRT and 93% were in the sRT group. Median PSA at sRT was 0.33 ng/ml. Patients with aRT harbored significantly worse baseline tumor and pathological characteristics such as PSA level (12.0 vs. 7.6 ng/ml), Gleason score 9–10 (30% vs. 9.8%), D’Amico high risk prostate cancer (97% vs. 56%), as well as pT3–4, pN1 and positive surgical margins rates (all p < 0.001). Similar observations were made for high-risk patients. No differences were observed for aRT vs. sRT with 60-month MFS rates of 85.1% vs. 95.4% (hazard ratio [HR] 0.60, p = 0.18). 60-months CSS-rates of 96.8% vs. 99.1% and 60-month OS-rates of 91.0% vs. 89.1% respectively (all p ≥ 0.15). Neither sensitivity analyses of high-risk patients nor multivariable adjusted Cox regression models revealed significant differences regarding MFS, CSS or OS in aRT vs. SRT comparison (all p ≥ 0.05), despite aRT showing qualitatively better OS results.

Within real-world setting, patients undergoing aRT harbor wore tumor characteristics. However, these differences did not translate into significant differences of mid-term oncological outcomes, relative to sRT patients. Similar observations were made within analyses of high-risk patients with pT3–4 and/or Gleason 8–10 and/or pN1 stage, nevertheless aRT showed slightly higher OS rates within this subgroup.