Core Viewpoint - The research reveals that cancer cells hijack iron-rich macrophages in the bone marrow to promote bone metastasis and anemia, opening new avenues for therapies to mitigate both bone metastasis and associated severe anemia [3][12]. Group 1: Mechanism of Cancer Metastasis - Cancer cells effectively "hijack" a specific type of macrophage, known as VCAM1+ CD163+ CCR3+ macrophages, which are responsible for recycling iron in the bone, depriving red blood cells of the iron needed for maturation [5][10]. - The study indicates that the hijacking of these macrophages not only leads to a lack of iron necessary for red blood cell development but also supports tumor growth in the bone [9][10]. Group 2: Implications for Anemia - The cancer cells' action results in the red blood cells being in an immature state, leading to anemia due to insufficient healthy red blood cell production [9][10]. - Tumor cells simulate red blood cells to adapt to the hypoxic environment of the bone tissue, utilizing the stolen iron to produce hemoglobin, which is crucial for oxygen transport [9][12]. Group 3: Research Significance - This research shifts the focus from solely studying cancer cells ("seeds") to understanding the surrounding microenvironment ("soil") that facilitates cancer metastasis [7][8]. - The findings have broader implications beyond metastatic breast cancer, potentially extending to other major cancer types, highlighting the importance of the tumor's manipulation of its environment [12].