ESTRO 2024 - Abstract Book

S1549

Clinical - Lower GI

ESTRO 2024

2583

Mini-Oral

Outcomes and Predictors of Response in Oligometastatic Colorectal Cancer Patients Treated with SBRT

Sara Stefanini 1,2 , Ciro Franzese 1,2 , Tiziana Comito 1 , Maria Massaro 1 , Beatrice Marini 1,2 , Marco Badalamenti 1 , Damiano Dei 1,2 , Luisa Bellu 1 , Ruggero Spoto 1 , Davide Franceschini 1 , Luciana Di Cristina 1,2 , Anna Bertolini 1,2 , Mariya Boyanova Ilieva 1,2 , Francesco Laurelli 1,2 , Pietro Mancosu 1 , Carmela Galdieri 1 , Stefano Tomatis 1 , Marta Scorsetti 1,2 1 IRCSS Humanitas Research Hospital, Department of Radiotherapy and Radiosurgery, Rozzano (Milan), Italy. 2 Humanitas University, Department of Biomedical Sciences, Pieve Emanuele (Milan), Italy

Purpose/Objective:

The oligometastatic setting represents an intermediate state of disease characterized by a limited number of metastases eligible for local treatment (1). Patients with colorectal cancer (CRC) present with a metastatic disease at the time of diagnosis in 20% of cases or become metastatic along the disease course in 25% of cases (2). Stereotactic Body Radiation Therapy (SBRT) represents a potential treatment option in these patients.

Material/Methods:

Patient population included in this retrospective study consisted of patients treated at our centre with SBRT either for synchronous or metachronous oligometastases from colorectal adenocarcinoma.

Patient considered eligible for inclusion had up to 5 metastases in a maximum of 3 different organs, as defined by the concept of oligometastatic state. Primary endpoints were overall survival (OS), local control (LC), and progression-free survival (PFS).

Results:

The study included 347 patients treated for a total of 820 oligometastatic lesions between 2008 and 2022. Slightly more than half of the patient were treated for a single lesion (n=207, 59.6%).

Most patients had a ECOG performance status of 0 (66.6%). All patients had a diagnosis of adenocarcinoma, and the majority had a primary disease originating from the colon (68%), followed by rectum (25.6%), and sigma (6.4%).

Mean time from diagnosis to metastases development was 21.2 months (ranging 0-167.9 months).

The median tumour volume was 14.1 cc (ranging 0.4 – 596.9 cc). Median total delivered dose was 48 Gy (ranging 25-75 Gy) in a median number of fractions of 4 (ranging 1-10), with a median biologically effective dose (BED) of 105.6 Gy.

Median duration of follow-up was 32.4 months (ranging 6 – 157.6 months).