More importantly, the in vivo data demonstrate that our injectable living prosthetic breast not only exhibited an inhibitory effect on the tumor recurrence for 28 days in the C57BL/6J mice via the re‐polarization of macrophages from M2 to M1 subtypes and an increasing ratio between CD8/CD4 T cells (both indicating tumor‐killing activities at the tumor microenvironment), but also supported and enhanced adipose regeneration in the C57BL/6J mice in 2 months. This evidence concerns the gene CD4 and neoplasm.