Impact of neoadjuvant chemotherapy followed by interval debulking surgery on survival in women with advanced non-serous ovarian, fallopian tube, or primary peritoneal cancer
To evaluate the survival impact of neoadjuvant chemotherapy followed by interval debulking surgery (NACT/IDS) versus primary debulking surgery (PDS) in patients with advanced epithelial ovarian cancer of non-high-grade serous carcinoma (HGSC) histology. A retrospective analysis was conducted using the Japan Society of Obstetrics and Gynecology tumor registry (2017 to 2022). Patients with FIGO stage III-IV ovarian, fallopian tube, or primary peritoneal cancer were classified by histology (HGSC or non-HGSC), and compared initial treatment. Overall survival (OS) was analyzed using multivariate Cox proportional hazard model and propensity score matching (PSM). Among 20,212 eligible cases, 14,718 (72.8 %) were HGSC and 5494 (27.2 %) were non-HGSC, primarily clear cell (2389;11.8 %) and endometrioid (1431;7.1 %) carcinomas. In HGSC patients, 7118 (48.4 %) received NACT, while in non-HGSC, 1203 (21.9 %) received NACT. Compared with HGSC, non-HGSC patients were younger, more frequently registered in eastern Japan, diagnosed at FIGO 2014 stage IIIA/IIIB, and underwent PDS and nodal evaluation (all, P < .05). In the overall cohort, non-HGSC histology was independently associated with poorer OS (adjusted-hazard ratio [HR]1.35, P < .001). Upstaging/IDS failure was higher in non-HGSC (36 %) vs HGSC (25 %, P < .001). After PSM, 5-year OS was comparable between HGSC patients who achieved IDS after NACT and those who underwent PDS (36.8 % vs 35.6 %; HR0.83, P = .12), whereas IDS failure was associated with markedly worse survival (3.9 %; HR3.12, P < .001). In non-HGSC, the rate of upstaging/IDS failure after NACT reached approximately 36 %; however, achieving IDS after NACT resulted in survival comparable to PDS, highlighting the need to select appropriate candidates.