To summarize, high amounts of CD15+MPO+ TANs or MPO+ cells at time of PT diagnosis enhanced the likelihood of having distant recurrent MBC (as opposed to de novo MBC), but high amounts of infiltrating CD15+MPO+ TANs or CD15+MPO− TANs also decreased the likelihood of having bone and skin metastases, in contrast to MPO+ cells that increased the likelihood of lung metastasis. This evidence concerns the gene MPO and metastasis.