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Possible breast cancer risks

Men and women discussing breast cancer

This page tells you about factors that researchers have looked at, or are looking at, to see if they could possibly increase the risk of getting breast cancer. There is information below about

 

A quick guide to what's on this page

Possible breast cancer risks

Researchers are investigating some factors that might increase breast cancer risk, including

  • Uneven breasts – A recent study showed that women who have one breast larger than the other may be at a slightly increased risk of developing breast cancer. But any increase in risk is small compared to other risk factors. For most women it is normal to have slightly uneven (asymmetrical) breasts.
  • Injury to the breast – Scientific research has not identified injury as a risk factor but one study suggested a link. We need more studies to prove or disprove this.

Pesticides, having a pregnancy terminated, and stress have all been investigated as possible causes of breast cancer. But research has found that they don’t seem to increase risk.

 

CR PDF Icon You can view and print the quick guides for all the pages in the About breast cancer section.

 

 

Having uneven breasts

A recent study showed that women who have one breast larger than the other may be at a slightly increased risk of developing breast cancer. But any increase in risk is small compared to other risk factors. 

For most women it is normal to have slightly uneven (asymmetrical) breasts. More research needs to be done before we know for sure how this may affect breast cancer risk. The important thing is to check your breasts regularly and be aware of how they usually look and feel. And to let your doctor know if you notice any changes, including unevenness.

 

Injury to the breast

Some women wonder if a past injury could have caused their breast cancer. Scientific research has not identified this as a risk factor but one study suggested a link. We need more studies to prove or disprove this. There is information about the injury and breast cancer study in our breast cancer questions section.

 

Pesticides

Some people think that pesticides increase the risk of breast cancer. Most studies have found that they don't increase cancer risk. But an American report in 2008 found that exposure to the pesticide DDT (dichlorodiphenyltrichloroethane) early in life may increase breast cancer risk. DDT is no longer used but it was widely used from the 1950s to the 1970s.

 

Having a pregnancy terminated

Pregnancy termination (abortion) has been researched  looked into in several different studies. It doesn't seem to increase breast cancer risk. Researchers thought it might, because of the effect of pregnancy on breast cells.

 

Stress

Research has been done into the effects of stress on breast cancer. Cancer Research UK's London Psychosocial Group led a study of women with breast cancer and found that stress did not make breast cancer more likely to come back. Another study called the Nurses' Health Study found no link with breast cancer risk.

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Updated: 7 December 2010