Preoperative neutrophil-to-lymphocyte ratio predicts 30 day postoperative morbidity and survival after primary surgery for ovarian cancer.

Objective: The preoperative neutrophil-to-lymphocyte ratio has been found to be an independent prognostic indicator for perioperative complications and survival outcomes in patients undergoing oncologic surgery for several malignancies. The objective of this study was to evaluate the role of the preoperative neutrophil-to-lymphocyte ratio in predicting 30-day postoperative morbidity and overall survival in advanced-stage high-grade serous ovarian cancer patients after primary surgery.

Methods: A retrospective study was conducted on consecutive patients who underwent primary surgery for high-grade serous ovarian cancer between January 2008 and December 2016 at a single tertiary academic institution in Toronto, Canada. Optimal thresholds for preoperative neutrophil-to-lymphocyte ratio were determined using receiver-operator characteristic curve analysis. Cox-proportional hazard models, Kaplan-Meier, and logistic regression analyses were performed.

Results: Of 505 patients with ovarian cancer during the study period, 199 met the inclusion criteria. Receiver-operator characteristic curve analysis generated optimal preoperative neutrophil-to-lymphocyte ratio thresholds of 2.3 and 2.9 for 30-day postoperative morbidity and survival outcomes, respectively. A neutrophil-to-lymphocyte ratio ≥2.3 was predictive of a composite outcome of 30-day postoperative complications (odds ratio 7.3, 95% confidence interval 2.44 to 21.81; p=0.0004), after adjusting for longer operative time and intraoperative complications. Postoperative complications included superficial surgical site infections (p=0.007) and urinary tract infections (p=0.004). A neutrophil-to-lymphocyte ratio ≥29 was associated with worse 5-year overall survival (57.8% vs 77.7%, p=0.003), and suggested no statistically significant difference in progression-free survival (33.8% vs 40.7%, p=0.054). On multivariable analysis, the neutrophil-to-lymphocyte ratio remained an independent predictor for overall survival (p=0.02) when adjusting for suboptimal cytoreduction (p≤0.0001).

Discussion: A preoperative neutrophil-to-lymphocyte ratio ≥2.3 and ≥2.9 is associated with greater risk of 30-day postoperative morbidity and worse overall survival, respectively. This marker may be used in conjunction with other risk assessment strategies to preoperatively identify high-risk patients. Further prospective study is required to investigate its role in clinical decision-making.