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Obesity, Smoking, Drinking Linked to Risk of Second Breast Cancer

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A study found that being obese, smoking, and drinking alcohol all increase the risk of breast cancer being diagnosed a second time in women previously diagnosed with hormone-receptor-positive disease.

The researchers looked at the records of more than 1,000 women successfully treated for hormone-receptor-positive early-stage breast cancer. About 360 of the women were later diagnosed with a new breast cancer in the opposite breast (known as contralateral breast cancer). The researchers wanted to know if being obese, smoking, and regularly drinking alcohol contributed to the risk of developing a second breast cancer.

The risk of developing a second breast cancer was:

  • 40% higher in women who were obese compared to women who weren't obese
  • almost doubled in women who drank seven or more alcoholic drinks per week compared to women who didn't drink alcohol or drank less
  • more than doubled in women who smoked compared to women who didn't smoke

The researchers also found that women who drank regularly AND smoked were more than 7 times more likely to develop a second breast cancer compared to women who didn't smoke or drink regularly.

The women in this study were treated in the mid-1990s. At that time, hormonal therapy wasn't used as regularly as it is today. Since obesity and alcohol use may affect breast cancer risk by increasing hormone levels, it's possible that these factors may have less of an effect now because so many women take hormonal therapy medicine to reduce the risk of hormone-receptor-positive early-stage breast cancer coming back after surgery. Hormonal therapy reduces the risk of hormone-receptor-positive breast cancer coming back by blocking the effects or limiting the production of estrogen. Still, research shows a link between breast cancer risk and obesity, smoking, and drinking alcohol.

If you have been treated for early-stage breast cancer, try to do all you can to lower both your risk of the cancer coming back AND your risk of a new, second breast cancer. Along with the treatment plan you and your doctor choose, a healthy diet and lifestyle can help keep these risks as low as possible:

  • Maintain a healthy weight and eat a low-fat diet that includes generous servings of fruits and vegetables.
  • Exercise regularly at medium intensity.
  • Don't smoke. If you do smoke, make the effort to quit.
  • Avoid alcohol.

Visit the Breastcancer.org Lower Your Risk section to learn about diet and lifestyle options to keep your risk as low as it can be.

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