One in eight women will be diagnosed with breast cancer in her lifetime. The five-year survival rate averages 90 percent. That’s because most tumors are detected early.

You have a higher risk of breast cancer if you:

  • Are an older woman

  • Have excess weight (and you’re postmenopausal)
  • Are sedentary
  • Consume alcohol often
  • Have a relative—especially a mother, sister, or daughter—who was diagnosed with breast cancer
  • Have mutations in genes (like BRCA1 and BRCA2) found in families with high rates of breast cancer
  • Had menstrual periods that began before age 12 or menopause that began after age 55
  • Were older than 30 when you had your first child
  • Took estrogen and progestin after menopause
  • Have dense breast tissue (seen on a mammogram)
  • Have abnormal breast cells (atypical hyperplasia or carcinoma in situ)

How diet, exercise, and other factors affect your risk of breast cancer

Gaining weight—even as little as an extra 10 to 20 pounds—is linked to an increased risk of breast cancer after menopause. Why?

“We have compelling evidence that higher blood levels of estrogen are associated with an increased risk of postmenopausal breast cancer,” says Regina Ziegler, a former researcher at the National Cancer Institute’s Division of Cancer Epidemiology & Genetics.

“In postmenopausal women, the ovaries no longer produce estrogen,” explains Ziegler, “so the dominant source is estrogens that are made in fat tissue in the breast and elsewhere.” (Dominant, that is, unless women take replacement hormones, which also raise risk.)

Excess insulin and inflammation may also spur tumors to grow

Among postmenopausal women not taking hormones, those with the highest insulin levels had twice the risk of breast cancer—and those with the highest levels of c-reactive protein (a marker of inflammation) had a 67 percent higher risk—than those with lower levels.

Also, women who have even a few servings of alcohol a week have a 10 percent higher risk of breast cancer than those who don’t drink. One to two daily drinks were linked to a 19 percent higher risk.

In contrast, “physical activity is protective,” notes Ziegler, “though it’s not clear whether it works by itself or by preventing weight gain.”

How fruits and vegetables may help

“The evidence has strengthened that vegetables and fruits may be associated with a reduced risk of breast cancers, especially estrogen-negative and other aggressive tumors,” says Ziegler. (Estrogen-negative cancers are less common, but more difficult to treat.)

“Though we can’t say definitively that fruits and vegetables can help prevent breast cancer, they’re worth eating to lower the risk of strokes, heart attacks, type 2 diabetes, and obesity.”

Warning signs of breast cancer

  • A painless lump in the breast or underarm area

  • Less-common symptoms: breast pain or heaviness, thickening, swelling, redness, discharge, nipple turned inward

Photo: Sebastian Kaulitzki/