ESTRO 2023 - Abstract Book

S1196

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ESTRO 2023

radiotherapy(RT) ± hormone therapy(HT) adapted to risk groups based on Multiparametric Magnetic Resonance Imaging (mMRI). We analyzed potential prognostic factors as well as acute and chronic toxicity of the administered treatment. Materials and Methods We retrospectively evaluated 140 consecutive patients diagnosed with prostate adenocarcinoma by ultrasound-guided biopsy(Gleason Score), determination of PSA level(ng/ml), digital rectal examination, in addition to mMRI. The patients were stratified in different risk groups according to NCCN (low (LR), intermediate (IR), high (HR) (including very high risk)). mMRI results were used as key factor to choose dose and volume of RT treatment and the necessity to associate HT. LR patients received 76-78Gy (2Gy/fraction), IR and HR patients received 78-80Gy (2Gy/fraction). The clinical target volume (CTV) included the prostate in LR patients, the prostate and seminal vesicles were included in IR and HR patients. CTV was extended to include extracapsular disease according to the mMRI extension in T3–T4 patients. IR and HR group received 6 and 24 months HT respectively. Toxicity was evaluated according to RTOG criteria. Results After a median follow-up of 104 months, in the LR group(n=15), 10y-BRFS was 86.7%, 10y-LRFS was 86.7%, 10y-MFS was 93.3% and 10y-OS was 100%. In the IR group(n=80) 10y-BRFS was 80.5%, 10y-LRFS was 86.1%, 10y-MFS was 92.6%, and 10y OS was 76%. In the HR group(n=45), 10y-BRFS was 72.8%, 10y-LRFS was 78.7%, 10y-MFS was 82.1%, and 10y-OS was 77% (2 patients died from prostate cancer). According to the results of the mMRI, there was a change in the risk group in 36 (25.7%) patients, 25 patients from LR to IR, 1 patient from LR to HR and 10 patients from IR to HR, no downgrades. There is a trend for higher metastatic relapse in patients who switched from IR to HR group (due to mMRI) versus the patients who remained in the IR group (20%, vs 1.58% p=0.059). Within the patients who remained in the HR group(n=34), 30 patients (88.23%) presented a change in the T-stage and in 7 patients (20.58%) a change in the RT volume was done. Multivariate analysis showed that locoregional relapse was strongly associated to distant relapse (OR=9.28; 95% CI:2.60-33.31).No cases of acute GIII were observed. Chronic GIII genitourinary, gastrointestinal and sexual toxicity were 2.8%, 0.7% and 1.2% respectively.

Conclusion To our knowledge, this is the first study with a 10-year follow-up of patients diagnosed with non-metastatic prostate cancer treated with radiotherapy adapted to risk groups according to mMRI with excellent efficacy and toxicity outcomes. These