ESTRO 2024 - Abstract Book

S1083

Clinical - Gynaecology

ESTRO 2024

Purpose/Objective:

New systemic therapies have led to a brand-new scenario, in which radiotherapy has a major role: the oligometastasic patient. Over the past few years, some evidence has come up along with the development of new treatment techniques such as image-guided radiotherapy (IGRT) and stereotactic ablative radiotherapy (SABR) 1,2 . Extreme hypofractionation schemes have demonstrated long-term disease control and even cure in oligometastasic patients1. Regarding ovarian cancer, around 60% of the patients are diagnosed at an advanced stage. The standard of care is cytoreductive surgery + chemotherapy, remaining radiotherapy’s role unclear. Despite being considered as a radiosensitive tumor, adjuvant whole abdominal radiation is no longer used, due mainly to high abdominal toxicity. Thus, with the emergence of SABR, radiotherapy is currently indicated as a salvage treatment in oligorecurrences of patients who are not fit for surgery 1,3 .

Our goal is to describe our institutional experience in salvage radiotherapy for patients with oligometastasic gynecological cancer.

Material/Methods:

A single-centre retrospective study was performed. 15 patients with different tumor recurrences, who previously underwent surgery + chemotherapy, were analyzed. Diagnosis and follow-up was conducted by computerized tomography and/or positron emission tomography imaging. Different radiotherapy schemes were delivered between August’19 and April’23. Local control (LC: defined as complete or partial response or radiological stability), progression-free survival (PFS), overall survival (OS) and median follow-up were analyzed, among others. Tumor response and acute and late toxicity were evaluated based on the Response Evaluation Criteria in Solid Tumors, 1.1 version, and the Common Terminology Criteria for Adverse Events, 5.0 version.

Results:

15 patients with 21 treated lesions were identified. Mean age was 60,48 ± 12,24 years and mean follow-up time was 22,71 ± 19,31 months. High-grade serous ovarian cancer was the most common histologic type diagnosed, being present in 80 % of our patients. Oligometastases appeared in different locations (12 lymph nodes and 9 parenchymal – liver, lung, adrenal, splenic, muscular and vaginal – lesions). In the cohort, 10 (66,67 %) of our patients are still alive. SABR was delivered to 18 (85,71 %) of the lesions, for a mean dose of 39,95 ± 7,47 Gy in 8 ± 5,32 fractions. A 100 % of radiological response was observed: complete radiologic response, partial response and stabilization was observed in 5 (23,81 %), 13 (61,9%) and 3 (14,29 %) metastases, respectively. Prior to SABR, 10 (66,67 %) patients were undergoing systemic therapies and 9 (60 %) patients switched to another scheme after concluding radiotherapy. LC at 12 and 24 months was 93,33 % and 80 %; mean PFS was 9,9 ± 8,01 months; OS at 12 months was 80,33 %. No G³3 toxicities were described.