Real-world study on the effect of PARPi as maintenance therapy on recurrent site after first-line chemotherapy in patients with high-grade serous epithelial ovarian cancer.

e17593 Background: This study investigated the effect of poly (ADP-ribose) polymerase inhibitors (PARPi) as maintenance therapy after first-line chemotherapy on recurrent site in patients with high-grade serous epithelial ovarian cancer (HGSOC). Methods: This study retrospectively analyzed 173 patients with HGSOC treated at Zhejiang Cancer Hospital and Jiaxing Maternity and Child Health Care Hospital between January 2017 and March 2024. The PARPi group comprised patients who received a PARPi as maintenance therapy after first-line chemotherapy (n=63), and the control group comprised those who did not (n=110). Results: There were no differences in both groups regarding age, body mass index (BMI), residual tumor after initial surgery, efficacy evaluation after first-line chemotherapy (P > 0.05). Among the 63 patients in the PARPi group and the 110 patients in the control group, thirty-eight and 28 whose recurrent site were widespread pelvic and abdominal peritoneum, respectively (hazard ratio HR: 2.37, 95% Confidence Interval (CI) 1.63-3.47, P < 0.0001). However, there was no significant statistical difference in lymph nodes recurrence between the two groups (HR: 0.95, 95% CI 0.69-1.26, P=0.72). In the subgroup analysis of the PARPi group, among 36 patients with breast cancer susceptibility gene (BRCA) mutations and 10 homologous recombination deficiency(HRD) negative patients, 21 and 7 patients developed pelvic and abdominal peritoneum recurrence (HR: 0.83, 95% CI 0.54-1.54, P=0.50), while 20 and 5 patients developed lymph node recurrence (HR: 1.11, 95% CI 0.63-2.45, P=0.75) respectively, with no statistically significant differences. Conclusions: Patients with HGSOC using a PARPi as maintenance therapy after first-line chemotherapy were more likely to cause widespread pelvic abdominal peritoneal recurrence while lymph node recurrence were similar to those who did not receive PARPi. BRCA status did not affect the recurrent site when using a PARPi as maintenance therapy after first-line chemotherapy. We should pay attention to these patients because using a PARPi as maintenance therapy after first-line chemotherapy might change the location and characteristics of recurrent lesions, which might affect the complete resection rate of secondary cytoreductive surgery Recurrence site analysis. Widespread pelvic abdominal peritoneal recurrence No widespread pelvic abdominal peritoneal recurrence Total PARPi 38 25 63 no PARPi 28 82 110 Total 66 107 173 Lymph node recurrence No lymph node recurrence Total PARPi 32 31 63 no PARPi 59 51 110 Total 91 82 173 widespread pelvic abdominal peritoneal recurrence no widespread pelvic abdominal peritoneal recurrence Total BRCA1/2 mutation 21 15 36 HRD negative 7 3 10 Total 28 18 46 Lymph node recurrence no Lymph node recurrence Total BRCA1/2 mutation 20 16 36 HRD negative 5 5 10 Total 25 21 46