ESTRO 2024 - Abstract Book

S2605

Clinical - Urology

ESTRO 2024

Prostate cancer: the role of salvage SBRT re-irradiation for intraprostatic relapse

Riccardo Carlo Sigillo, Giuseppe Facondo, Gianluca Vullo, Mattia Falchetto Osti, Maurizio Valeriani

AOU Sant'Andrea, La Sapienza, UO Radioterapia Oncologica, ROMA, Italy

Purpose/Objective:

The aim of this study was to evaluate the outcomes and toxicities of local re-irradiation with stereotactic body radiation therapy (SBRT) in patients with local recurrence of prostate cancer after curative radiotherapy.

Material/Methods:

Thirty-eight patients (median age 78 years, range 64-89) were treated with salvage SBRT between January 2014 and February 2022. All patients had previously undergone curative external beam radiotherapy treatment between 2000 and 2017. Median time between two RT treatments was 106.9 months (range 38.6-228). All patients had clinical/radiological local relapse in the prostate and no distant metastasis. All patients underwent multiparametric MRI and PET/CT (Choline or PSMA). Thirty-six patients (94.7%) received 30 Gy in 5 fractions/3w, 2 (5.3%) received 25 Gy in 5 fractions/3w. All patients underwent image-guided radiotherapy (IGRT) using cone-beam computed tomography (CBCT) system as daily pre-treatment imaging. Fourteen out of 38 patients (36.8%) received also androgen deprivation therapy (ADT) at the time of recurrence. Toxicity was evaluated using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Criteria. Biochemical control was assessed according to the Phoenix definition (NADIR + 2 ng ml (-1)). Median actuarial OS from the end of re-irradiation (OS1) was 41.7 months (95% CI 39.35 - 44.05, range 8.9 - 96.97) and the median actuarial OS from the end of the first RT treatment (OS) was 154.2 months (95% CI 130.85-177.55, range 73.5 – 286.4). Analyzing OS since the end of the first curative RT treatment, there was a statistically significant correlation (p=0.038) with whether or not ADT was used: without the use of ADT the 10- and 20-year survival is 93.3% and 77.8%, and with the association of ADT 83.5% and 66.9%, respectively. Another statistically significant finding (p=0.022) is the correlation of OS and the variable "time between the two RT treatments" (<100 months, >100 months): the 10-year OS in patients with <100 months is 76%, while in those with a time >100 months is 100%. Nine patients (23.7%) died during the study; six of these for causes other than the disease under study. Three and 5 year biochemical recurrence free survival were 56.9% and 38.8%, respectively; the median BRFS is 44.03 months (95%CI 17.41 – 70.65). Three and 5-year local control (LC) were 78.2%; the median LC value was not reached. Three and 5-year metastasis-free survival (MFS) were 70.9% and 65.9%; the median MFS value was not reached. Three and 5-year disease-free survival (DFS) were 54.2% and 37%; the median DFS value is 38 months (95%CI 17.96-58.03, range 5.1 – 69.03). Genito-urinary toxicities: G1 acute in 14 patients (36.8%), G2 acute in 4 patients (10.5%); G1 late in 13 patients (34%), G2 late in 6 patients (15.7%). Gastro-intestinal toxicities: G1 acute in 2 patients (5.3%), G2 acute in 1 patient (2.6%); G1 late in 1 patient (2.6%), G3 late in 1 patient (2.6%). Results:

Conclusion: