ESTRO 2024 - Abstract Book

S2368

Clinical - Urology

ESTRO 2024

A meta-analysis of three randomized trials has demonstrated that immediate adjuvant radiotherapy (aRT) and early salvage radiotherapy (sRT) yield similar outcomes in prostate cancer (PCa) patients. However, sRT is associated with significantly lower rates of toxicity. In this analysis, we aim to evaluate the preliminary results concerning outcomes and toxicity in a group of PCa patients enrolled in a prospective trial focused on early sRT following biochemical relapse during the follow-up period.

Material/Methods:

Between March 2018 and December 2022, 721 patients underwent radical prostatectomy and were enrolled in the prospective trial EASY-1 (EArly Salvage radiotherapY-1). Inclusion criteria encompassed patients with PCa treated surgically, including those with pT2 disease featuring positive surgical margins, pT3a regardless of margin status, or pT3b disease with negative surgical margins. All patients had a PSA level below the detectable limit (<0.01 ng/mL) within 40 days after surgery. The surveillance protocol involved periodic PSA assessments. Specifically, PSA levels were monitored every 2 months during the 1st year post-surgery, every 3 months in the 2nd and 3rd years, every 4 months up to the 5th year, and thereafter every 6 months up to the 10th year. In the event of biochemical relapse, confirmed by two consecutive PSA values ≥0.2 ng/mL and aided by 68Ga -PSMA PET/CT-based restaging, patients received sRT. We analyzed 2-year event-free survival (EFS) among patients experiencing biochemical relapse and assessed toxicity following sRT.

Results:

Among the 721 enrolled patients, 64 patients (8.9%) encountered biochemical relapse. Of these, 50 patients (78%) have already completed restaging and sRT. The median follow-up duration was 31 months, and the median PSA range at biochemical relapse was 0.23 ng/mL (ranging from 0.10 to 5.82 ng/mL). The International Society of Urological Pathology (ISUP) grade distribution was as follows: Grade 1 in 1.6%, Grade 2 in 9.3%, Grade 3 in 34.4%, Grade 4 in 32.8%, and Grade 5 in 21.9% of cases. The 2- year EFS rate was 56.3%. Notably, no acute or late grade ≥3 gastrointestinal (GI) or genitourinary (GU) toxicity was recorded.

Conclusion:

Despite close monitoring of PSA levels, the 2-year EFS rate was unexpectedly low in patients experiencing biochemical recurrence. Further analyses are warranted to identify patients at low risk of biochemical recurrence (who may not require aRT) and to establish the optimal PSA threshold for planning sRT.

Keywords: salvage radiotherapy , prostate cancer, outcomes

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