Chronic lymphocytic leukemia (CLL) is a slow-growing cancer of the blood and bone marrow in which the body produces large numbers of abnormal B lymphocytes, a type of white blood cell that normally helps fight infection. These leukemia cells accumulate gradually in the bone marrow, blood, lymph nodes, and spleen, crowding out healthy blood-forming cells and leading over time to problems such as increased infections, anemia, and easy bruising or bleeding. Because CLL usually progresses slowly, many adults—most often older individuals—may have no
