The informatrion below is from the American Cancer Society/Breast Cancer pages.



Breast cancer risk and lifestyle choices

<>Not having children or having them later in life:<> Women who have not had children, or who had their first child after age 30, have a slightly higher risk of breast cancer. Being pregnant many times and at an early age reduces breast cancer risk. Being pregnant lowers a woman's total number of lifetime menstrual cycles, which may be the reason for this effect.

<>Recent use of birth control pills:<> Studies have found that women who are using birth control pills have a slightly greater risk of breast cancer than women who have never used them. This risk seems to go back to normal over time once the pills are stopped. Women who stopped using the pill more than 10 years ago do not seem to have any increased risk. It's a good idea to talk to your doctor about the risks and benefits of birth control pills.

<>Using post-menopausal hormone therapy (PHT):<> Post-menopausal hormone therapy (also known as hormone replacement therapy or HRT), has been used for many years to help relieve symptoms of menopause and to help prevent thinning of the bones (osteoporosis).

There are 2 main types of PHT. For women who still have a womb (uterus), doctors most often prescribe estrogen and progesterone (known as combined PHT). Estrogen alone can increase the risk of cancer of the uterus, so progesterone is added to help prevent this. For women who no longer have a uterus (those who've had a hysterectomy), estrogen alone can be prescribed. This is known as estrogen replacement therapy (ERT).

  • Combined PHT: Use of combined PHT increases the risk of getting breast cancer. It may also increase the chances of dying from breast cancer. Breast cancer may also be found at a more advanced stage. Five years after stopping PHT, the breast cancer risk seems to drop back to normal.
  • ERT: The use of estrogen alone does not seem to increase the risk of developing breast cancer very much, if at all. But when used long-term (for more than 10 years), some studies have found that ERT increases the risk of ovarian and breast cancer.

At this time, there seem to be few strong reasons to use PHT, other than for short-term relief of menopausal symptoms. Because there are other factors to think about, you should talk with your doctor about the pros and cons of using PHT. If a woman and her doctor decide to try PHT for symptoms of menopause, it is usually best to use it at the lowest dose that works for her and for as short a time as possible.

Not breast-feeding: Some studies have shown that breast-feeding slightly lowers breast cancer risk, especially if the breast-feeding lasts 1½ to 2 years. This could be because breast-feeding lowers a woman's total number of menstrual periods, as does pregnancy

<>Alcohol:<> Use of alcohol is clearly linked to an increased risk of getting breast cancer. Women who have one drink a day have a very small increased risk. Those who have 2 to 5 drinks daily have about 1½ times the risk of women who drink no alcohol. The American Cancer Society suggests limiting the amount you drink to one drink a day.

<>Being overweight or obese:<> Being overweight or obese is linked to a higher risk of breast cancer, especially for women after change of life or if the weight gain took place during adulthood. Also, the risk seems to be higher if the extra fat is around the waist. But the link between weight and breast cancer risk is complex. And studies of fat in the diet as it relates to breast cancer risk have often given conflicting results. The American Cancer Society recommends you stay at a healthy weight throughout your life and avoid gaining too much weight.

<>Lack of exercise:<> Studies show that exercise reduces breast cancer risk. The only question is how much exercise is needed. One study found that as little as 1 hour and 15 minutes to 2½ hours of brisk walking per week reduced the risk by 18%. Walking 10 hours a week reduced the risk a little more. The American Cancer Society suggests that you exercise for 45 to 60 minutes 5 or more days a week.

Uncertain risk factors

<>High fat diets: <>Studies of fat in the diet have not clearly shown that this is a breast cancer risk factor. Most studies found that breast cancer is less common in countries where the typical diet is low in fat. On the other hand, many studies of women in the United States have not found breast cancer risk to be linked to how much fat they ate. Researchers are still not sure how to explain this difference. More research is needed to better understand the effect of the types of fat eaten and body weight on breast cancer risk.

The American Cancer Society recommends eating a healthy diet that includes 5 or more servings of vegetables and fruits each day, choosing whole grains over processed (refined) grains, and limiting the amount of processed and red meats.

<>Antiperspirants and bras:<> Internet e-mail rumors have suggested that underarm antiperspirants can cause breast cancer. There is very little evidence to support this idea. Also, there is no evidence to support the idea that bras cause breast cancer.

<>Abortions:<> Several studies show that induced abortions do not increase the risk of breast cancer. Also, there is no evidence to show a direct link between miscarriages and breast cancer. For more detailed information, see our document, Is Having an Abortion Linked to Breast Cancer?

<>Breast implants:<> Silicone breast implants can cause scar tissue to form in the breast. But studies have found that this does not increase breast cancer risk. If you have breast implants, you might need special x-ray pictures during mammograms.

<>Pollution:<> A lot of research is being done to learn how the environment might affect breast cancer risk. At this time, research does not show a clear link between breast cancer risk and environmental pollutants.

<>Tobacco Smoke:<> Most studies have found no link between active cigarette smoking and breast cancer. An issue that continues to be a focus of research is whether secondhand smoke (smoke from another person's cigarette) may increase the risk of breast cancer. But the evidence about secondhand smoke and breast cancer risk in human studies is not clear. In any case, a possible link to breast cancer is yet another reason to avoid being around secondhand smoke.

<>Night Work:<> A few studies have suggested that women who work at night (nurses on the night shift, for instance) have a higher risk of breast cancer. This is a fairly recent finding, and more studies are being done to look at this.

Last Medical Review: 09/29/2009
Last Revised: 09/29/2009