Introduction High grade serous carcinoma (HGSC) is the most common epithelial type of ovarian cancer. The aim of the present study was to validate the role of the CRS system in an independent cohort of patients with advanced ovarian cancer treated with NACT followed by IDS with or without HIPEC on progression free survival (PFS) and overall survival (OS).

Methods This is a single center retrospective study with a total of 55 patients. The collected data was analysed and statistically evaluated using SPSS-PC-25 version. Clinicopathological factors were compared by chi-square test. Kaplan–Meier method was used to estimate PFS and OS, and comparisons were made by the log rank test. A P-value of <0.05 was considered statistically significant.

Results CRS 1 was achieved in 6/55 patients (10.9%); CRS 2 in 36/55 (65.5%); CRS 3 in 13/55 patients (23.6%). The median overall survival was 49 months. No significant difference in OS was observed between the CRS scores. Median OS with CRS 1&2 was 46 months whereas that of CRS 3 was 49 months. The median RFS was 19 months. Difference of 7 months in RFS was noted between CRS 1&2 group and CRS 3 group (15 and 22 months, respectively) but statistically not significant (p=0.069). However statistically significant difference was noted when all the scores were analyzed individually without grouping (P=0.028).

Conclusion/Implications CRS3 was significantly associated with improved PFS compared to CRS1/2. The validation of CRS in a practical clinical setting shows its reliability as a biomarker, suggesting its potential use in guiding treatment decisions and designing clinical trials.