Leukemia - Chronic Lymphocytic - CLL: Risk Factors

Approved by the Cancer.Net Editorial Board, 10/2017

ON THIS PAGE: You will find out more about the factors that increase the chance of developing CLL. Use the menu to see other pages.

A risk factor is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. Knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices. The cause of CLL is unknown. There is no evidence that exposure to radiation, chemicals, or chemotherapy increases a person’s risk of developing CLL. However, the following factors may raise a person’s risk of developing CLL:

  • Family history. Although it is uncommon, having more than 1 close relative with CLL or some other lymph-related cancer may be linked with an increased risk of CLL. People with a first-degree relative with CLL, such as a parent, sibling, or child, are 2 to 4 times more likely to develop the disease. In order to learn more about families with a history of CLL, there is a registry that affected families can join at the National Cancer Institute.

  • Age. CLL is most common in older adults, is rare in young adults, and hardly ever develops in children. About 90% of people diagnosed with CLL are older than 50. The average age of people diagnosed with CLL is 71.

  • Gender. Men develop CLL more often than women.

  • Race/Ethnicity. B-cell CLL is more common in people of Russian and European descent, and hardly ever develops in people from China, Japan, or Southeast Asian countries. It also occurs commonly in black people. The reason(s) for these differences is not known.

  • Agent Orange. The U.S. Department of Veterans Affairs lists CLL as a disease associated with exposure to Agent Orange, a chemical used during the Vietnam War.

  • Monoclonal B-cell lymphocytosis. This is a condition in which people have higher than usual levels of lymphocytes. But, these levels are not high enough to classify as CLL. There is a slight risk that monoclonal B-cell lymphocytosis can turn into CLL.

The next section in this guide is Symptoms and Signs. It explains what body changes or medical problems CLL can cause. Use the menu to choose a different section to read in this guide.