Background: Chemotherapy response score (CRS) applied to omental metastases obtained at the time of interval debulking surgery (IDS) has been used to quantify response to neoadjuvant chemotherapy (NACT) in advanced stage ovarian cancer patients. The score has been correlated with both progression free survival (PFS) and overall survival (OS). This CRS score has not been studied in advanced stage endometrial cancer. The aim of the current study is 1) to apply the CRS to omental and adnexal metastases obtained at IDS of advanced stage endometrial cancer patients and 2) to investigate the association between the CRS score and surgical outcome, PFS and OS. Methods: Patients with clinical stage III-IV endometrial cancer (endometrioid, serous, clear cell, carcinosarcoma) were identified through the endometrial cancer database, billing data and tumor board notes (2003-2019) from the University of Chicago. Patients were included if they received NACT followed by IDS (R0 no gross residual, optimal < 1 cm residual or suboptimal ≥ 1 cm residual disease). Patients who received pre-operative radiotherapy were excluded. Pathology specimens from primary and metastatic sites were reviewed by the study pathologist blinded to clinical outcome. Histologic specimens from the omental and adnexal metastases were assigned a single quantitative score of 1 (no/minimal tumor response), 2 (appreciable tumor response with viable tumor) or 3 (complete/near complete response) using the CRS system as previously described by Bohm et al (JCO 2015; 33:2457-63). Results: A total of 40 patients were available for analysis. Median age 63.5, median BMI 32 kg/m². There is a significant association between omental CRS and optimal IDS (p = 0.029) but no significant association between the adnexal CRS and optimal IDS (p = 0.145). Cox regression analysis identified CRS omentum [2: HR = 0.095, p = 0.001; 3 HR = 0.088, p = 0.004] and CRS adnexa [2: HR = 0.24, p = 0.007] predictive of PFS. There was not enough evidence to comment on any association between CRS with OS. Conclusions: Omental CRS2, CRS3 are associated with optimal IDS. Omental CRS2, CRS3 and adnexal CRS2 are prognostic for improved PFS in stage III – IV endometrial cancer patients after neoadjuvant chemotherapy.

PFS/OS in median months