In fact, in the skeletal system, SOSTDC1 is essential for bone metabolism, bone density maintenance, and fracture healing.[35] In the immune system, SOSTDC1 is secreted by a subpopulation of follicular helper T‐cells and is required for regulatory follicular T‐cell differentiation.[63] Further functional analyses will be meaningful to explore the roles of SOSTDC1 in TNBC tumor microenvironment and bone metastasis. Here, SOSTDC1 is linked to neoplasm.