ESTRO 2024 - Abstract Book

S2436

Clinical - Urology

ESTRO 2024

bivariate analysis. Statistical analyses were performed using STATA 15.1. Results were considered as statistically significant at p value< 0,05.

Results:

PET-PSMA with complete follow-up was performed in 85 patients aged 48-78 years (mean age 69 years) with biochemical relapse of prostate cancer after primary treatment. Most patients were staged T2 (50.58%) - T3 (48.23%), cases N1 (10.58%), Gleason score > 7 (96%) with mean nadir PSA values of 0.13 ng/ml following primary treatment with radical intent. In 53% of patients (45/85) had positive PET-PSMA results, pre-study median PSA was 0.59 ng/ml and median PSA doubling time was seven months. There is a positive relationship between PSA values and PSA doubling time in months with the ability to detect disease in the PET-PSMA study (AUC 0.74). The disease detection rate (DR) was 32%, 60% and 77.8% for PSA values less than 0.5 ng/ml, between 0.5 - 1.0 ng/ml and greater than 1.0ng/ml respectively. For PSA doubling time the detection rate was 62%, 47% and 26.7% for those cases less than 6 months, between 6 and 12 months and greater than 12 months respectively. From the sum of all positive PET-PSMA studies, a total of 90 lesions were found in the 45 patients who were negative on conventional (CT/GGO) and/or PET-Choline studies (17% prostate/bed, 60% adenopathies, 20% bone lesions and 3% visceral metastases). The disease detection rate increased significantly with higher PSA values (p 0.004) and shorter PSA doubling time (p 0.007). PSA value of 0.5 ng/ml and DT-PSA of 9 months were established as optimal cut-off points according to RoC curves. In 84% of patients with positive PET-PSMA results (38/45) there were changes in therapeutic management. Treatment changes were classified into different categories (salvage surgery, radiotherapy/SBRT +/- ADT or ARSI, ADT +/- ARSI or systemic treatment). Once treatment changes occurred the median PSA was 0.08ng/ml. In PET PSMA negative cases a watchful waiting approach was taken.

Conclusion:

Our results support that the PET-PSMA study in patients with biochemical relapse prostate cancer after primary treatment with radical intent is a powerful tool that provides greater diagnostic capacity compared to other tests, conditioning changes in therapeutic management in 84% of patients with positive results in the study.

Keywords: Prostate cancer, PET-PSMA, biochemical relapse

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