Clearing up the Confusion: When Should a Woman Begin Annual Mammograms?

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The American Cancer Society has issued updated guidelines for breast cancer screenings that say women with an average risk for breast cancer should begin screening mammograms at age 45 instead of age 40 - although women still have the opportunity to begin screenings at age 40, if they prefer.

The guidelines recommend that between the ages of 45 and 54, women should be screened annually and women 55 and older should transition to screenings every other year, but can still continue annual screenings if they prefer. 

"We agree with the new guidelines from the American Cancer Society and the United States Preventive Services Task Force that annual screening mammography, beginning at age 40, saves the most lives," said Brett Parkinson, MD, medical director of breast imaging at Intermountain Medical Center's Breast Care Center. "However, we're concerned that the cancer society didn't make a strong recommendation to begin screening until age 45, and for women to transition to biennial exams after age 55."

The American Cancer Society says it recognizes that mammography reduces breast cancer deaths as much as 48 percent in women who are actually screened. Early detection of breast cancer is critical for improving breast cancer survival. But the conversation now taking place is about balancing the risks and benefits of screening mammography, as different organizations recommend different ages for starting annual screening mammography.

What are the harms of mammography?

The biggest potential harm of annual mammograms is the false positive screening exam, which means some women are called back in for additional views and ultrasound,  based on something identified in the breast tissue during their mammogram. Some groups think these false positives cause unnecessary worry for women, who fear they have cancer, just to be told their follow-up tests show there's nothing to worry about. So the principal harm is not really medical, but psychological. Only 2% of women who are screened will actually have a medical procedure, usually just a minimally invasive needle biopsy.

To put things in perspective, for every 1,000 women who undergo screening mammography, about 100 are called back  for additional imaging.  Following that second appointment, eighty of them are told everything is okay. Twenty of these women may undergo a needle biopsy to determine if an abnormality in the breast tissue is cancerous. Only five will be diagnosed with breast cancer. 

What are the benefits of mammography?

The older a women is, the greater her chance of developing breast cancer. The key to saving a woman's life is to detect and treat breast cancer in its earliest stages. The more advanced the cancer, the more difficult it is to treat. Studies have shown that beginning mammogram screening at age 40 saves the most lives.

Some younger women whose breast cancers were caught early with screening mammography have expressed concern about the recommendation of starting annual screening at age 45. ; they say they would not have survived had they followed those guidelines. 

"When you look at the harms versus the benefits, I think it's pretty obvious that the benefits of annual screening mammograms, starting at age 40, certainly outweigh the minimal harms of being called back for additional mammographic views or ultrasound," said Dr Parkinson. "At Intermountain Healthcare, we continue to encourage women to begin annual screening mammograms at age 40, and continue every year as long as they are healthy and have a life expectancy of at least 10 years."