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Possible risk factors for non Hodgkin lymphoma

Men and women discussing non Hodgkin's lymphoma

This page is about possible risk factors for NHL. There is not enough evidence for them to be thought of as definite risk factors. We have information about these possible risk factors because we are sometimes asked about them and those that have been researched are described below


A quick guide to what's on this page

Possible risk factors for non Hodgkin lymphoma

These are possible risk factors for NHL. We have included information on these because we are sometimes asked about them. But we must stress that there is not enough evidence for these to be thought of as definite risk factors. They include

  • Weed killers and pesticides
  • Hair dye
  • Sunlight
  • Smoking
  • Obesity
  • Diabetes
  • Certain medicines
  • Alcohol
  • Hormones

CR PDF Icon You can view and print the quick guides for all the pages in the about NHL section.



Chemicals at work

Studies have looked at chemicals to kill weeds (herbicides) and insects (insecticides and pesticides), and the risk of NHL. A recent analysis of published studies (meta analysis) shows that people who work with pesticides (such as farmers) have an increased risk of NHL. 

Most studies have looked at herbicides, insecticides and pesticides used in agriculture. But some studies have looked at their use in the home. The findings of these studies show no link with the risk of NHL, but more research is needed. 

Some studies have linked exposure to solvents to an increased risk of NHL. But, others have not. An overview of the evidence about benzene (a solvent known to cause leukaemia) showed that it can increase the risk of NHL. There is some evidence that exposure through work to trichloroethylene also increases the risk.


Hair dye

There is no clear evidence of a link between the use of any type of hair dye and NHL. Most studies have shown no link with hair dye. There may be a small link between hair dye use and some types of lymphoma but if there is any increase in risk, it is likely to be extremely small. Research in China and the USA is looking at whether women with certain types of gene changes may be more at risk of developing lymphoma if they use hair dyes.

There is detailed information about hair dye and cancer risk in the questions and answer section.


Sunlight and vitamin D

Some studies show that sunlight may lower NHL risk, but others say the opposite, and at least one shows no effect. Sunlight helps our bodies to make vitamin D, so if sunlight can protect against NHL it may be because people who've been in the sun have higher vitamin D levels in their blood. 

Some studies have looked at levels of vitamin D in the blood and diet, but so far the evidence isn't clear enough to say whether or not there is a link between vitamin D and NHL. 

So more research is needed to see if there is a link with sunlight, and if so whether it is related to vitamin D levels.



Unlike for some other cancer types, smoking is not thought to have a major impact on NHL risk. Some studies have shown an increased risk of some types of NHL in smokers, but others have found no link.



There is evidence that people who are overweight or obese may have a higher risk of developing a type of NHL called diffuse large B cell lymphoma (DLBCL). And another study found that people who had a higher body mass index when they were young adults had a higher risk of developing DLBCL and follicular lymphoma (FL). But other types of NHL do not appear to be linked with being overweight or obese. More research is needed to confirm this.



There is some evidence that people with type 2 diabetes may have an increased risk of NHL. However, more studies are needed to be sure.



Some, but not all studies have found there might be a link between antibiotic use and NHL. One large study showed that people who had taken more antibiotics during adult life had an increased risk of NHL. But we don't know if this was to do with the antibiotics, or with the illnesses they were treating. 

Other studies have shown that people who take statins might have a lower risk of NHL. Statins are the drugs to stop blood clots that doctors sometimes give to lower the risk (or after effects) of heart attacks or strokes. More research is needed to understand more about how these medicines affect NHL risk. 



Some studies suggest that alcohol can lower the risk of NHL. But the picture isn't completely clear. More research is needed to find out if the type and amount of alcohol people drink affects whether or not the risk of NHL is reduced, and by how much.



Studies suggest that factors affecting a woman’s hormone levels may affect NHL risk. Some studies have shown that women who have a higher number of pregnancies have a reduced risk of NHL, but other studies do not show a link. A recent study found that the overall risk of NHL was not affected by the number of pregnancies. But the risk of follicular lymphoma was lower for women who had a higher number of pregnancies.

A reduced risk of NHL has also been shown in studies for women who are taking, or have taken, oral contraceptives. But again, other studies have not found this. A recent study found that oral contraception did not affect the risk of NHL overall. But the risk of follicular lymphoma was higher for women who had used oral contraception. This increase in risk was highest for women who used oral contraception many years before they were diagnosed with lymphoma. This may be linked with oral contraceptives before the mid 1970's, which contained a higher dose of hormones than they do today.

A recent study found that the risk of NHL was lower for women who took hormone replacement therapy (HRT) from the age of 50, compared to women who have never taken HRT. This lower risk was in women who are taking HRT at the moment, and was not for women who have taken HRT in the past. 

Overall, findings of studies into hormonal factors and NHL risk are still unclear and we cannot be sure about the effect on risk, if any.

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Updated: 7 November 2014