Risk factors

Factors that may increase the risk of chronic lymphocytic leukemia include:

• Your age. This disease occurs most often in older adults.
• Your race. White people are more likely to develop chronic lymphocytic leukemia than are people of other races.
• Family history of blood and bone marrow cancers. A family history of chronic lymphocytic leukemia or other blood and bone marrow cancers may increase your risk.
• Exposure to chemicals. Certain herbicides and insecticides, including Agent Orange used during the Vietnam War, have been linked to an increased risk of chronic lymphocytic leukemia.
• A condition that causes excess lymphocytes. Monoclonal B-cell lymphocytosis (MBL) causes an increased number of one type of lymphocyte (B cells) in the blood. For a small number of people with MBL, the condition may develop into chronic lymphocytic leukemia. If you have MBL and also have a family history of chronic lymphocytic leukemia, you may have a higher risk of developing cancer.