Introduction/Background*The benefit of surgery and maintenance treatment with parp inhibitors (PARPi) has been recently shown in ovarian cancer (OC) recurrence. Also, the efficacy and safety of stereotactic body radiotherapy (SBRT) is demonstrated in patients with metastatic, persistent, and recurrent OC. The management of oligometastatic progression (OMP) during PARPi maintenance is unclear and continuing the treatment beyond progression could be an option.
Methodology This is an observational, retrospective, single arm study. Patients affected by OC recurrence treated with PARPi in maintenance setting received surgery or SBRT, if OMP occurred. OMP was assessed by either CT scan or PET/CT scan, in case of isolated disease progression (one nodule) or discrete diffusion (up to three nodules in different locations) or progression in “sanctuary” site. Maintenance treatment was continued until extensive progression of disease. Primary objectives were: Progression Free Survival 1 (PFS1), defined as the time elapsed from the start of PARPi and OMP; post-progression-PFS (ppPFS), defined as the time elapsed from OMP and the last follow up (FU). Beyond-progression PFS (bpPFS), defined as the time elapsed from the start of PARPi and the definitive progression of disease or last FU (PFS1+ppPFS), and efficacy of surgery versus SBRT at OMP were secondary objectives.
Result(s)*From June 2017 to December 2020 186 OC patients were treated with PARPi maintenance at recurrence. Of these 24 (13%) developed OMP (58% lymphnodes, 17% peritoneal, 25% visceral disease). Median age was 51 years. Olaparib and Niraparib maintenance were administered to 9 (38%) and 15 (62%) patients, respectively. Median PFS1 was 23 months [Confidence Interval (CI) 95% 11 – 34]. When OMP occurred 9 (38%) and 15 (62%) pts were subjected to surgery and SBRT, respectively. Median ppPFS was 6 months (CI 95% 5 – 7). At the time of this publication 62.5% patients are still on treatment with PARPi beyond progression.
Conclusion*OC patients, who have an OMP during PARPi maintenance at recurrence, may continue to benefit from PARPi treatment if combined with local treatment. Molecular assessment at oligometastatic and extensive progression could provide further information to define PARPi resistance mechanisms according to the type of disease progression.
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