Leukemia is a cancer of the blood cells, and typically starts in blood-forming tissue, such as bone marrow.

There are many different leukemiaLeukemiaCancer in the blood types and the names usually come from the cellCellThe smallest unit of life; what all tissues are made up of they affect. These cancersCancerAbnormal cells that grow out of control [may invade other tissues and may spread into other parts of the body]; Also called malignancy. include chronic lymphocytic leukemia (CLL)Chronic Lymphocytic Leukemia (CLL)A type of blood and bone marrow cancer in the white blood cells (cells that fight infection). It usually progresses slowly and is typically seen in older adults., among others. At Merck, we’re committed to developing treatments that can help improve the lives of leukemia patients.