Introduction/Background*Epithelial ovarian cancer is a lethal gynaecological cancer with a 5 year survival of < 30% in advanced stages. Recently, NACT followed by surgery is being increasingly used to treat advanced tubo-ovarian high-grade serous carcinoma (HGSC) following the results of randomized trials that demonstrated non- inferior overall survival and morbidity compared to primary surgery.The chemotherapy response score (CRS) has been described to assess the chemotherapy response in patients with HGS tubal & ovarian carcinoma. Studies have shown that the three-tier CRS based on omental assessment of residual disease helps in predicting progression free survival (PFS) and overall survival.

Methodology A retrospective study to assess the prognostic significance of CRS in patients who undergo surgery after 3-4cycles NACT and obtained optimal cytoreduction from January 2016 to July 2018 for HGS ovarian carcinoma in a tertiary care centre in India. CRS was analysed by a single pathologist in omental samples. Patients were followed up for the first 3 years and PFS calculated from diagnosis to radiological evidence of progression or starting of chemotherapy for recurrence. Progression free survival was estimated using the Kaplan - Meier method and compared using the log-rank test.

Result(s)*A total of 76 patients with omental slides were included in the analysis. The median follow up period was 44 months. Ten Patients had CRS 1, 36 had CRS 2 and 30 patients had CRS 3. The median progression free survival for patients with CRS 1, 2 and 3 were 7 months , 16 months and 33 months respectively (p value 0.001) The progression free survival probability at 4 years for patients with CRS1 was 0, CRS 2 was 16.7% and CRS 3 was 44.4% (p value0.001).

Conclusion*The CRS was significantly associated with PFS. The CRS scoring of omental samples provides clinicians prognostic information on patients with HGS ovarian cancer undergoing IDS. This helps in early detection of non-responders and triaging patients for further management.