CA-125 reduction during neoadjuvant chemotherapy is associated with success of cytoreductive surgery and outcome of patients with advanced high-grade ovarian cancer

Introduction: The objective was to assess whether an early response to neoadjuvant chemotherapy in women with advanced ovarian cancer may predict short- and long-term clinical outcome.

Material and methods: This is a retrospective study of all women with stage III-IV tubo-ovarian cancer treated with neoadjuvant chemotherapy at a single center in Montreal between 2003 and 2014. Logistic regression models were used to evaluate the association between cancer antigen 125 (CA-125) levels during neoadjuvant chemotherapy and debulking success. Cox proportional hazard models were used to estimate hazard ratios and their respective 95% CI for death and recurrence. Harrell's concordance indices were calculated to evaluate which variables best predicted the chemotherapy-free interval and overall survival in our population.

Results: In all, 105 women were included. Following the first, second, and third cycles of neoadjuvant chemotherapy, CA-125 levels had a median reduction of 43.2%, 85.4%, and 92.9%, respectively, compared with CA-125 levels at diagnosis. As early as the second cycle, CA-125 was associated with overall survival (hazard ratio 1.03, 95% CI 1.01-1.05, per 50 U/mL increment). By the third cycle, CA-125 did not only predict overall survival (hazard ratio 1.04, 95% CI 1.01-1.08), but it predicted overall survival better than the success of debulking surgery (Harrell's concordance index 0.646 vs 0.616). Both absolute CA-125 levels and relative reduction in CA-125 levels after 2 and 3 cycles predicted the chance to achieve complete debulking (P < .05).

Conclusions: Reduction of CA-125 levels during neoadjuvant chemotherapy provides an early predictive tool that strongly correlates with successful cytoreductive surgery and long-term clinical outcome in women with advanced high-grade serous and endometrioid ovarian cancer.