APOA1 and breast neoplasm: Although the exact mechanism of APOA1 protein antitumor activity is unclear, its immunomodulatory and anti-inflammatory effects on the tumor microenvironment exert the protective activity in mouse tumor models.26,40,41 APOA1 protein can reduce the recruitment of myeloid-derived suppressor cells, moderate antiangiogenesis, and increase the number of CD8 + T cells.26,36,40,42,43 The present study revealed that APOA1 expression is negatively associated with ESTIMATE immune score in breast tumors among both East Asian and Western patients.