Provided herein are compositions comprising isolated placental stem cells for use in methods for suppressing the proliferation of cells of a bone-related cancer in a human individual, or for treatment of a human individual having a bone-related cancer, wherein said placental stem cells are adherent to tissue culture plastic, are CD34 - , CD10 + , CD105 + and CD200 + as detectable by flow cytometry, and are not trophoblasts, cytotrophoblasts or bone marrow-derived mesenchymal stem cells.