Cancer Data Base

Important news for women - being exposed to chemicals and pollutants before her mid 30s may greatly increase a woman's risk of breast cancer after she goes through menopause according to a new study. The research involved 556 postmenopausal Canadian women who'd been diagnosed with cancer of the breast between the ages of 50 and 75 years old. There was also a control group of 613 women of the same age group, who were free of breast cancer.

The team measured the women's occupational exposure to almost 300 substances. After accounting for the usual factors linked with an increase risk of breast cancer, the team found a link between breast cancer and some of these substances.

The risk of breast cancer after menopause was highest in the women who'd been exposed to these substances before 36 years old.

The risk went up for each added decade of exposure before this age. So twenty years of exposure... say starting in the teens, would be expected to double a woman's risk.

The exposure to acrylic fibers at work had a seven fold increase risk of cancer of the breast. The risk was almost double among those exposed to nylon fibers. Exposure to polycyclic aromatic hydrocarbons (in petroleum products) before the age of 36 tripled the risk of breast cancer according to the study authors.

These finding are consistent with the thinking that the tissue of the breast is more sensitive to harmful chemicals if the exposure occurs when the breast cells are still active - before a woman reaches her 40s. This is also thought to be a factor in the increases in cancer of the breast in developed countries.

The incidence of breast cancer in the United States is one in eight, about 13%, or 13 out of every 100 women over the course of a lifetime.

Your own personal risk may be higher or lower, depending on family history, reproductive history, lifestyle and environment. Besides skin cancer, breast cancer is the most often diagnosed cancer in American women - one in four cancers are of the breast. As of 2008, there are almost 2.5 million breast cancer survivors in the U.S. alone.

Experts commenting on the study do express caution. Positive associations like those found between chemical exposure and cancer of the breast can appear just by chance, and will only carry serious weight when supported by evidence from later research. The team also calls for more detailed studies that focus on specific chemicals in terms of risk for breast cancer.

To reduce your risk of breast cancer, whether you've been exposed to any of the substances identified in the research or not, here are some things you can do for yourself...

- Control your weight - being overweight, especially after menopause, increases your risk. More fat in the body produces more estrogen, which is what increases the risk of cancer developing and growing.

- Eat healthy - while no food can keep you from getting cancer of the breast, eating well can make your body strong and healthy, keeping your risk as low as possible. It's a good idea to limit red and processed meats and animal fats (fat in cheese, ice cream and milk). A diet that's low in fat, loaded with fruits and veggies is generally a good bet.

- Exercise - doing 45 to 60 minutes of physical activity on five or more days of the week is key, and evidence is growing that this can reduce your risk of cancers.

- Limit alcohol consumption

- Don't smoke

- Limit stress/anxiety - while there isn't clear proof stress/anxiety can increase your breast cancer risk, anything you do to reduce stress and make your life better plus make your immune system stronger will help.

- Estrogen exposure - through being overweight, drinking too much or taking combined hormone replacement therapy (HRT).

- Recent oral contraceptive use - using these medications may slightly increase your risk of breast cancer, but only for a short time. If you've stopped taking birth control pills more than ten years ago, you don't appear to have any increase risk.