Prognostic utility of preoperative neutrophil-lymphocyte ratio in cats with malignant mammary tumors.

Although studies have determined the neutrophil-lymphocyte ratio (NLR) to be a useful prognostic predictor in various human cancers, little is known regarding its preoperative prognostic significance in feline mammary tumors (FMTs). Thus, the present study aimed to determine the prognostic utility of preoperative peripheral blood NLR in malignant FMTs. Accordingly, medical records of 34 cats that had undergone mastectomy were searched, after which those histopathologically confirmed to have malignant FMTs were included. Univariate analysis was used to determine the effect of each variable on one-year survival time. Factors determined to be significant during univariate analysis were subsequently included for multivariate analysis. Receiver operating characteristic analysis was used to assess the accuracy of the tests for predicting one-year survival. Univariate analysis showed that a high NLR and large tumor size were significantly associated with shorter survival times (P < 0.01, for both). No significant differences in other factors were observed. Multivariate analysis showed that a high NLR (hazard ratio, 25.03; 95% confidence interval, 2.98-210.40; P < 0.01), but not tumor size and age, was an independent prognostic factor for poor outcomes. The sensitivity and specificity of the NLR (cut-off, 5.67) for predicting one-year survival were 93.8% and 88.9%, respectively. This study suggests that the NLR could potentially be used as a preoperative prognostic factor in FMTs. Preoperative NLR may help to establish therapeutic modalities by allowing prognostic evaluation among cats with mammary tumors.