Chronic lymphocytic leukemia

You are here: 

Risk factors for chronic lymphocytic leukemia

A risk factor is something (such as a behaviour, substance or condition) that increases the risk of developing cancer. Most cancers are the result of many risk factors, but sometimes chronic lymphocytic leukemia (CLL) develops in people who don’t have any of the risk factors described below.

The risk of developing CLL increases with age. It usually occurs in people over the age of 50 years. More men than women develop CLL. It is also more common in people of Russian and European descent than people of Chinese, Japanese or Southeast Asian ancestry.

Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.

You may wonder about radiation exposure. There is significant evidence showing that there is no association between radiation and CLL.

Known risk factors

There is convincing evidence that a family history of CLL increases your risk for CLL.

Possible risk factors

The following factors have been linked with CLL, but there is not enough evidence to show they are known risk factors. Further study is needed to clarify the role of these factors for CLL.

Exposure to herbicides or pesticides

Agent Orange is a herbicide that was used during the Vietnam War. Some studies have linked exposure to Agent Orange to a higher risk of developing CLL. Other studies have suggested that long-term exposure to some pesticides through farming or other jobs may be linked to an increased risk of CLL.

Being overweight or obese

People who are overweight or obese have a higher risk of developing certain types of cancer. Some studies have shown that people who are overweight or obese have a higher risk of developing leukemia than people with a normal body weight.

Unknown risk factors

It isn’t known whether or not exposure to certain industrial chemicals, such as benzene, is linked with CLL. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if exposure to certain industrial chemicals is a risk factor for CLL.

Questions to ask your healthcare team

To make the decisions that are right for you, ask your healthcare team questions about risks.


Dr Troy Harkness Finding new ways to treat drug-resistant cancers

Read more

What’s the lifetime risk of getting cancer?

Icon - 1 in 2

The latest Canadian Cancer Statistics report shows about half of Canadians are expected to be diagnosed with cancer in their lifetime.

Learn more