Methods of use of early apoptotic cell populations and compositions thereof disclosed herein, including methods of treating a cancer or a tumor, extending survival times of a subject suffering from a cancer or a tumor, and reducing the size or reducing the growth rate of a cancer or a tumor, wherein subjects are administered apoptotic cells or compositions thereof. Cancers may include solid tumors or diffuse cancers, for example leukemia. In certain instances compositions may include additional chemotherapeutic agent. Further, inactivated early apoptotic cell populations are disclosed and methods of making the same.