MPO and breast cancer: Furthermore, the absence of prognostic association between circulating levels of NETs and recurrence in localized BC in our study may be partially due to the lack of a standardized definition of “high” levels of NETs, differences in detected components of NETs (DNA, NE, MPO, or citrullinated histones), and whether NETs should be measured intratumorally (primary tumor or metastatic lesions) or in plasma samples (7).