The optimal number of lymph nodes removed in maximizing the survival of breast cancer patients

Abstract

The number of lymph nodes removed is one of the important predictors for survival in breast cancer study. Our aim is to determine the optimal number of lymph nodes to be removed for maximizing the survival of breast cancer patients. The study population consists of 873 patients with at least one of axillary nodes involved among 1890 patients from the University of Malaya Medical Center (UMMC) breast cancer registry. For this study, the Chi-square test of independence is performed to determine the significant association between prognostic factors and survival status, while Wilcoxon test is used to compare the estimates of the hazard functions of the two or more groups at each observed event time. Logistic regression analysis is then conducted to identify important predictors of survival. In particular, Akaike’s Information Criterion (AIC) are calculated from the logistic regression model for all thresholds of node involved, as an alternative measure for the Wald statistic (χ2), in order to determine the optimal number of nodes that need to be removed to obtain the maximum differential in survival. The results from both measurements are compared. It is recommended that, for this particular group, the minimum of 10 nodes should be removed to maximize survival of breast cancer patients.