The role of cancer stem cells has been demonstrated for some cancers. Recently, research indicated that solid tumors may originate from bone marrow stem cells. Bone marrow-derived cells have recently been shown to contribute to stromal formation, especially angiogenesis and lymphvasculogenesis. Moreover, the interaction and the cell fusion between cancer cells and bone mesenchymal stem cells could enhance the aggregative ability of cancer cells. Bone marrow derived cells home to tumor-specific pre-metastatic sites to provide a permissive niche for incoming tumor cells. Since bone marrow-derived cells play an important role in carcinogenesis, angiogenesis and metastasis, bone marrow-derived cells are not only the tool for cancer therapy, but also the targets for cancer therapy.