ESTRO 2024 - Abstract Book

S2590

Clinical - Urology

ESTRO 2024

1 European Institute of Oncology, IRCCS, Division of Radiation Oncology, Milan, Italy. 2 University of Milan, department of Oncology and hematology, Milan, Italy. 3 University of Piemonte Orientale (UPO), Department of Translational Medicine, Novara, Italy

Purpose/Objective:

High-risk prostate cancer (PCa) represents a fairly complex scenario with a range of predicted outcomes and widely discussed local and distant recurrence rates. Guidelines recommend surgery or external beam RT (EBRT) + long term androgen deprivation therapy (ADT) ± a brachytherapy boost. Currently, there is no consensus on prophylactic whole pelvis irradiation. Nowadays, the number of studies involving extreme hypofractionation in this setting is relatively low, and, despite being cited in clinical practice guidelines, the current level of evidence is too low to implement extreme hypofractionation as a standard of care. The aim of the present study is to evaluate the efficacy and safety of ultrahypofractionated RT (UHRT) +/- a simultaneous integrated boost (SIB) on intraprostatic dominant lesion(s) (DIL) +/- androgen deprivation therapy (ADT) in a real world cohort of high and very high-risk in PCa patients.

Material/Methods:

Patients with high and very high-risk PCa, according to NCCN risk class, who underwent curative UHRT +/- SIB on DIL +/- ADT were retrospectively included. At the end of RT treatment PSA measurements were performed every 3 months. Age adjusted Charlson Comorbidity Index (CCI) was calculated at baseline. Biochemical progression (BP) was assessed according to Pheonix definition. Clinical progression (CP) was defined as the presence of local or distant metastasis at radiological imaging. Maximum acute and late gastrointestinal (GI) and genitourinary (GU) toxicities were collected according to RTOG scale. All patients signed an informed consent for research purpose.

Results:

From January 2013 to December 2021 a total of 143 consecutive patients matched inclusion criteria. Median age at diagnosis was 76 years (range 51- 88 years). Median PSA at diagnosis was 7.25 ng/ml (range 0.7 - 220.4) and most of patients had a CCI ≤ 5 (81%). Staging was performed in the majority of patients with conventional imaging (CT scan - 63.6%- and/or bone scan – 70.6%), while only 22.4% underwent Choline-PET and 2.8% whole-body MRI. The main characteristics of the study population are reported in Table 1 . Thirty-seven (25.9%) patients were included in high-risk class for iPSA, 36 (25.2%) for extension of tumour (T), and 101 (70.6%) for Gleason score (GS). A total of 118 (82.5%) patients had only 1 risk factor, while 20 (14%) had 2 risk factors and only 5 (3.5%) had 3 risk factors. All patients underwent UHRT in 5 fractions every other day with a dose/fraction within 6.50 and 7.25 Gy. Median prostate CTV Volume (data available for 116 patients- 81.1%) was 60 cc (IQR 46.01 – 78.26). Among them, 44 (30.8%) patients received a SIB on DIL of 7.5/8 Gy fractions.