Risk Factors for Chronic Lymphocytic Leukemia (CLL)

There are very few known risk factors for chronic lymphocytic leukemia (CLL).

A risk factor is anything that raises your chances of getting a disease like cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like your age or family history, can’t be changed.

But having a risk factor, or even many risk factors, doesn’t mean you will get the disease. And some people who get the disease may have few or no known risk factors.

Here is what we do know about the risk factors for CLL.

Getting older

The risk of CLL goes up as you get older. The average age of people when they are diagnosed with CLL is around 70 years, and about 9 out of 10 people with CLL are over age 50.

Having certain chemical exposures

Agent Orange: Some studies have linked exposure to Agent Orange to an increased risk of CLL. (Agent Orange was an herbicide used during the Vietnam War.)

Pesticides: Some other studies have suggested that farming and long-term exposure to certain pesticides and other chemicals may be linked to an increased risk of CLL, but more research is needed to be sure.

Family history

First-degree relatives (parents, siblings, or children) of people with CLL are at higher risk for this cancer.

Being male

CLL is slightly more common in males than in females. The reason for this is not clear.

Race/ethnicity

In the United States, CLL is more common in White people than in people of other races/ethnicities.

CLL is more common in North America and Europe than in Asia. Asian people who live in the United States do not have a higher risk than those living in Asia. This is why experts think the increased risk is more likely related to genetics, not environmental factors.

Monoclonal B-cell lymphocytosis (MBL)

This is a condition in which people have higher than usual levels of B lymphocytes in their blood, but the levels aren’t high enough to qualify as CLL.

MBL is often thought of as a precursor to CLL. This means that basically everyone with СLL has МΒԼ first, even if it’s never diagnosed and labeled as MBL. But only a small percentage of people diagnosed with ΜΒL will go on to develop CLL.