Purpose: To assess the significance of CA-125 regression as a prognostic indicator and predictor of optimal cytoreduction at interval debulking surgery (IDS) in women with ovarian or primary peritoneal carcinoma receiving neoadjuvant chemotherapy (NAC).
Methods: 63 women treated between 2004 and 2007 with neoadjuvant platinum-based chemotherapy followed by IDS were studied retrospectively. Pre-operative CA-125 values were used to calculate a regression coefficient (CA-125r) using exponential regression analysis. Outcome endpoints were overall survival (OS), time to CA-125 progression (TTC) by Rustin criteria and time to second-line treatment (TTS).
Results: Women with a CA-125 half-life greater than 18 days had a significantly worse OS compared to those with a half-life less than 12 days on univariate testing (HR 3.34, 95% CI 1.25-8.94, p = 0.017). On multivariable analysis, CA-125r was an independent predictor of OS [HR 1.18 (per 0.01 increase in CA-125r), 95% CI 1.01-1.40, p = 0.043]. CA-125r was independently predictive of TTC and TTS (HR 1.17, p ≈ 0.03 for each). CA-125r was also predictive of achieving optimal cytoreduction at IDS (AUC 0.756, p < 0.001).
Conclusions: CA-125 regression rate during pre-operative NAC is of independent prognostic value. CA-125 regression rate strongly predicts for optimal cytoreduction.