Introduction Assessment of chemotherapy response helps timing of interval debulking surgery. This study evaluated RECIST, CA125, HE4 and Ki67 as predictors of chemotherapy response.

Methods Women with stage III and IV high grade serous carcinoma of ovary undergoing neoadjuvant chemotherapy entered this prospective cohort study. Pre and post chemotherapy CA125 and HE4 were measured. Ki67 levels were evaluated in adnexal/omental biopsy (pre- chemotherapy) and final pathology specimen (post- chemotherapy). Radiological response was calculated using RECIST; those with complete, partial response or stable disease underwent surgery. Receiver operating characteristic curves were used to calculate cut offs for post NACT CA125, HE4 and Ki67 for predicting CRS score.

Results Thirty six women were evaluated by RECIST, out of which 23 underwent IDS with CRS1(n=3), CRS 2 (n=5) and CRS3 (n=15). Although no association was noted between RECIST and CRS, lower post NACT CA125 and HE4 levels were significantly associated with complete/partial response on RECIST (p=0.01 and 0.002 respectively). Surgical PCI score showed strong correlation with post NACT radiological PCI (p=0.008). One point increase in surgical PCI decreased the odds of CRS3 by 37%. On ROC analysis, post NACT HE4 level ≤125.65 pmol/L was the most sensitive (86.87%) whereas post chemotherapy Ki67 ≤8% was the most specific (100%) predictor of CRS3. Percentage decrease in Ki67 >80% was found to have PPV of 100% for predicting CRS3.

Conclusion/Implications Ki67, surgical PCI and HE4 are promising markers for predicting response to NACT and can be explored further for prediction of survival outcomes.