RESUMEN
PURPOSE: The aim of this observational, retrospective, multicenter study (Epimetheo) was to analyze the activity and the safety of SBRT during PARP inhibitors (PARPi) maintenance, in a series of oligometastatic ovarian cancer (OC) patients. METHODS: Patients treated with PARPi in maintenance setting received SBRT if oligometastatic progression occurred. Maintenance treatment was continued until the extensive progression of the disease. The primary endpoints of the study were: next systemic treatment change-free survival (NEST-FS), and acute and late toxicity; the secondary endpoints were: the rate of clinical complete response (CR), the 2-year actuarial local control (LC, progression of disease inside SBRT field) rate on "per lesion" basis, the 2-year actuarial progression free-survival (PFS), and 2-year overall survival (OS). RESULTS: From April 2018 to September 2023, SBRT was used to treat 74 OC patients with a total of 158 lesions (98 lymph nodes and 60 parenchymal lesions) under PARPi maintenance. Olaparib, Niraparib, and Rucaparib were administered to 41.9%, 48.6%, and 9.5% of patients, respectively. CR, Partial Response, Stable Disease, and Progressive Disease (PD) were observed in 115 (72.8%), 32 (20.3%), 9 (5.7%), and 2 lesions (1.3%), respectively. Severe toxicities were reported in less than 3% of patients. The actuarial median NEST-FS was 10 months, with a range of 6.7 to 13.3 months. The 12- and 24-month actuarial NEST-FS rates were 44.9% and 31.4%, respectively. The 2-year actuarial LC, PFS and OS were 68.1%, 22.5% and 77%, respectively with differences figures between complete and not complete responders. The achievement of CR was found to be correlated with an improvement in LC and OS. CONCLUSIONS: This study reports the activity and the low toxicity profile of SBRT in association with PARPi in oligometastatic OC patients. A rapid, minimally invasive, and cost-effective treatment such as SBRT may be proposed as a means of prolonging NEST-FS and maintaining an effective treatment regimen involving PARPi.