IntroductionThe role of derived neutrophil-to-lymphocyte ratio (dNLR) in predicting the prognosis of patients with triple-negative breast cancer (TNBC) has not been well studied. Here, we attempted to investigate the significance of dNLR in predicting the prognosis of patients with surgical (nonmetastatic) TNBC.MethodsA total of 281 patients diagnosed with surgical TNBC in The First Affiliated Hospital of University of Science and Technology of China from February 2005 to March 2015 were retrospectively included in this study. Kaplan–Meier curve analysis was used to assess the disease-free survival (DFS) and overall survival (OS). We used Cox regression model to assess the prognostic significance of pretreatment dNLR and other clinicopathological parameters in TNBC patients.ResultsThe median DFS in TNBC patients who had low dNLR and high dNLR was 28.9 and 15.1 months (P<0.001), respectively, whereas the median OS in patients who had low dNLR and high dNLR was 71.2 and 42.3 months (P<0.001), respectively. In patients aged ≤50 years and with invasive ductal carcinoma, a low dNLR predicted better DFS and OS compared with a high dNLR. Multivariate analysis demonstrated that the increased dNLR was a risk factor of poor DFS (HR=1.90, 95% CI: 1.52–2.46, P=0.007) and OS (HR=2.56, 95% CI: 1.69–3.58, P=0.001).ConclusionPretreatment dNLR is an independent factor of prognosis for TNBC patients, which potentially allows clinical doctors to improve outcomes of patients with high dNLR by treating with aggressive therapy, such as high-dose adjuvant chemotherapy and radiotherapy.

In IEEE 802.11 wireless local area networks (WLANs), an important technique for medium access control (MAC) is the distributed coordination function (DCF). Two access mechanisms are provided by DCF, the default basic access mechanism and the optional request-to-send/clear-to-send (RTS/CTS) mechanism. The performance of IEEE 802.11 DCF networks has been predicted recently by NS-2 simulator based on a unified analytical model presenting the delay, throughput and stability [1]. NS-3 and OMNeT++ provide an essential platform to model IEEE 802.11 physical (PHY) and MAC layers, nevertheless the accuracy of which is yet not investigated. In this paper we present two studies, first is a comparative simulation study of the unified IEEE 802.11 DCF analytical model [1], by considering distinct network conditions, various topologies, different access modes and discrete system parameters in NS-3 and OMNeT++. A Linux based testbed is setup to validate the mathematical model and the simulation results. The second is the optimization study to adaptively tune the RTS threshold, so that the network operates in an access mode which steers to the maximum network throughput performance. An explicit expression of RTS threshold, verified by the simulations in NS-3 and OMNeT++, is obtained in contrast to previous studies based on channel estimation and numerical calculations. Performance evaluation is done by comparing the simulation, testbed and theoretical results. This study not only proves the credibility of the theoretical model of IEEE 802.11 DCF, but also assures that the results obtained from NS-3 and OMNeT++ are persuasive and provides a foundation for RTS threshold analysis in IEEE 802.11 WLANs for practical network design considerations.

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