Predictors of survival in advanced-stage, high grade primary peritoneal serous cystadenocarcinoma: An NCDB based analysis.

e16482 Background: High-grade primary peritoneal cystadenocarcinoma (HPPC) is a rare and aggressive malignancy originating from the peritoneal lining, frequently diagnosed at advanced stages with a poor prognosis. Despite its severity, data on clinical behavior, prognostic factors, and survival outcomes remain limited, particularly in advanced disease. This study utilizes the National Cancer Database (NCDB) to identify key predictors of survival to enhance clinical understanding and inform treatment strategies. Methods: Using the NCDB, we conducted a retrospective analysis of patients diagnosed with HPPC from 2010 to 2017. The primary cohort included AJCC stage III-IV, high grade pathologies. Immunotherapy and chemotherapy were combined into a single variable, systemic therapy (ST) as certain drugs were reclassified in the NCDB during the study period. Treatment modalities included systemic therapy alone (ST), surgery alone (S), and surgery with systemic therapy (S+ST). Kaplan-Meier survival analysis and Accelerated Failure Time (AFT) model were used for estimation of survival outcomes. STROBE guidelines were followed for reporting. Results: A total of 1,539 patients were included. Of these, 935 (60.8%) were aged ≥65 years, 1,430 (92.9%) were White, 872 (57%) had Medicare insurance, and 593 (38.57%) received care in Comprehensive Community Cancer Programs. 225 patients (14.6%) received ST, 84 (5.5%) received S, 1,095 (71.1%) received S+ST, and 135 (8.8%) received unspecified regimen combinations. mOS, however, varied by stage and treatment. In stage III, mOS was 28.02 months with ST, 30.23 months with S, and 51.15 months with S+ST (p < 0.05). In stage IV, mOS was 20.47 months with ST, 4.47 months with S, and 41.17 months with S+ST (p < 0.05). Collectively, covariate adjustment using AFT showed that S+ST significantly improved survival over ST alone (HR 0.63, p < 0.01), while S alone showed no statistically significant benefit (HR 0.93, p = 0.64). Older patients (≥65 years), with Charlson-Deyo Score (CDS) of 1 (vs 0; HR 1.17, p < 0.05), and those with oligometastatic disease M1 (vs M0; HR 1.24, p < 0.01) exhibited worse survival outcomes. Race, gender, insurance, and facility type did not significantly impact mortality, but patients treated in the East South Central (HR 1.82, p < 0.001) and the West South Central (HR 1.42, p = 0.038) had worse survival compared to the Northeast. Conclusions: Older age, burden of comorbidities, presence of metastasis, and treatment in certain geographic regions appear to be associated with worse outcome. Surgery combined with systemic therapy significantly improves survival outcomes, highlighting the importance of a multimodal approach in advanced stage HPPC.