This research is proposed to prospectively assess if KELIM score can accurately predict treatment outcomes, in patients with advanced HGSOC receiving NACT. 

All newly diagnosed patients with HGSOC and FIGO Stage III or IV deemed to be inappropriate for primary debulking surgery by the multidisciplinary team and fit to receive NACT will be recruited into the study. Serum CA-125 levels will be measured and recorded at various time points: a. at the time of diagnosis, b. before every NACT cycle, c. prior to IDS and d. during every follow up visit after treatment completion. In addition, various other parameters related to the study, including intra-operative details and post-operative histological details(eg: Chemotherapy Response Score(CRS) will be recorded. KELIM score will be calculated for these patients using the first three serum CA-125 values during the first 100 days from the start of neoadjuvant chemotherapy, using a mathematical algorithm available on the website: https://www.biomarker-kinetics.org/CA- 125-neo.

Patients will be grouped into two groups as per their KELIM Score(< 1 or ≥ 1) and the score will then be correlated with various parameters which are related to treatment outcome. After surgery, patients will complete the remaining chemotherapy and CA-125 will be recorded during follow up visits. Maintenance chemotherapy with targeted agents or PARP inhibitor drugs will be based on the treating team.

Standard-of-care protocol for patient follow up will be followed. Rise of serum CA-125 levels above 35U/mL, and/or new onset symptoms suggestive of disease recurrence will initiate imaging with contrast enhanced CT/MRI of the abdomen and/or CT thorax. Radiological confirmation of disease recurrence will be considered as indication of restarting treatment for recurrence.