Is there a threshold for red cell distribution width to predict malignancy in breast masses?

Background: Red cell distribution width (RDW) has been shown to have predictive properties in different diseases as well as solid cancers. Aim: We aimed to investigate the discriminative properties of RDW in benign and malignant breast lesions. Subjects and Methods: In a retrospective cohort study the files of patients who underwent surgery for fibroadenomas (Group A) and breast cancer with axillary lymph node metastasis (Group B) were reviewed. The pathology reports and laboratory parameters and demographics of the patients were recorded for comparison. The patients were later excluded if they had an hemoglobin level below 12 mg/dl and the outliers were removed for a comparison. Seventy-six patients in the fibroadenoma group and 62 patients in the breast malignancy group were compared for the RDW levels to predict the presence of malignancy. Receiver operating characteristic curves were plotted for RDW and a threshold for prediction of malignancy was calculated. Results: The difference in RDW levels between group A and group B was found to be significant, 13,10% (IQR 12.60 -13.70) versus 13,80% (IQR 13.10-14.40) respectively, P = 0,00. The area under the curve was 0.71 (95% confidence interval 0.62 to 0.79), P = 0,00. For the threshold of 13,75 the positive predictive value was 67.35 (95% CI 55.72 to 77.17) and negative predictive value was 67.42 (95% CI 60.76% to 73.44). Conclusion: The RDW levels, after adjusted for anemia, were found to have a positive prediction for malignancy in more than two thirds of the patients for the level of 13.75%.