Let's say you're a 45-year-old woman without a family history or other elevated risk factor for breast cancer, or a 70-year-old woman and don't have a higher risk for breast cancer. Should you get a mammogram?

Until the American College of Physicians released its new guidelines last month in the Annals of Internal Medicine, the answer would have been yes in both cases.

And the answer is still yes, if you go by the American Cancer Society's recommendations.

These sets of recommendations vary widely.

The new recommendation for women ages 40 to 49 of average risk for breast cancer is to talk to their doctors, but it caution that the harm associated with mammography at this age — mainly false positives that come from the density of younger tissue — might outweigh the benefits.

These guidelines recommend that women ages 50 to 74 get a mammogram every two years.

After age 75 — or before if they're not expected to live another 10 years — women of average risk should not get screenings.

The American Cancer Society tells a woman with an average risk that she can choose to have a mammogram from age 40 to 44. At 45, she should get a mammogram every year. At 55 and older, she should get one every two years, or continue getting one every year — her choice. She should continue doing mammograms as long as she's healthy and expected to live another 10 years.

Confused? Us too.

Dr. Julie Sprunt, a breast surgeon at St. David's Medical Center and Texas Breast Specialists - Austin, walked us through the new recommendations and what she recommends.

While the guidelines are based on good data about women of average risk, "we worry that perhaps your breast cancer will be diagnosed at a later stage," Sprunt says. "The earlier we find breast cancer, the better you tend to do."

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Sprunt says she would be surprised to see the American College of Physicians' guidelines become the standard for care. "Most doctors I know are not going to comply with these guidelines," she says.

Because the two sets of guidelines differ, especially for younger women, Sprunt says it's important to have a discussion with your doctor about your comfort level with screening and the anxiety that might follow if your mammogram results are designated as suspicious. That would result in follow-up biopsies, even though it could just be because you have younger, denser tissue.

"I would rather 100 women have an unnecessary biopsy to catch one younger woman's breast cancer," Sprunt says.

Even if you elect to wait until age 50 to have your first mammogram, start monthly breast self-exams at age 20 to detect changes in tissue. Signs that something might be wrong include feeling a mass, a nipple becoming inverted, nipple discharge, changes in the shape of the breast, skin that protrudes or pain in an area.

If you feel a lump, it doesn't necessarily mean cancer. "Some just have lumpy, bumpy breasts," Sprunt says, but you should get checked out.

Sprunt recommends starting mammogram conversations with your doctor beginning at age 40, but no later than age 50. Your doctor can assess your risk factors as well as look into whether you want to consider genetic testing based on your family's history.

The one thing Sprunt wants to make sure women hear: "The most important thing is to get mammograms."

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