Screening Mammograms Lead to Earlier Stage at Diagnosis, Lower Need for Aggressive Treatment

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Several large studies, including a review by the U.S. Preventive Services Task Force in 2009 and a study on the causes of death in the United Kingdom in 2013, have questioned the value of screening mammograms.

Doctors who question the value of mammograms say that while mammograms do save lives, for each breast cancer death prevented, three to four women are overdiagnosed. Overdiagnosis means either:

  • a screening mammogram finds a suspicious area that would have been eventually diagnosed as cancer by other means, without any effect on prognosis
  • a screening mammogram finds a suspicious area that never would have affected a woman’s health if it hadn’t been found or treated

False positive results from screening mammograms also have helped fuel the debate about the value of breast cancer screening. When a mammogram shows an abnormal area that looks like a cancer but turns out to be normal, it’s called a false positive. Ultimately the news is good: no breast cancer. But the suspicious area usually requires follow-up with more than one doctor, extra tests, and extra procedures, including a possible biopsy. There are psychological, physical, and economic costs that come with a false positive.

These studies and the resulting stories in the media have fueled an ongoing debate about the value of screening mammograms.

Since that time, the American Medical Association, the American Congress of Obstetricians and Gynecologists, the American College of Radiology, the National Cancer Institute, and the National Comprehensive Cancer Network all have issued guidelines saying that all women should be eligible for screening mammograms starting at age 40. In 2015, the American Cancer Society recommended that screening mammograms start at age 45.

Now a study suggests that screening mammograms every 2 years or more often are linked to breast cancers that are diagnosed at an earlier stage, which lowers the need for more aggressive treatment.

The research was presented at the American Society of Breast Surgeons 2018 Annual Meeting. Read the abstract of “Impact of screening mammography interval on stage and treatment in women diagnosed with breast cancer” (PDF) on page 51 of the official proceedings.

“This study shows that women who don’t get screened have later-stage disease and require more aggressive treatment,” said Elisa Port, M.D., associate professor of surgical oncology at Mount Sinai Hospital, in a phone interview with reporter Elaine Schattner.

To do the study, the researchers looked at the screening mammogram records of 1,125 women older than 40 who had been diagnosed with breast cancer at Mount Sinai between September 2008 and May 2016:

  • 819 women (73%) had a screening mammogram 1 to 24 months before being diagnosed
  • 306 women (27%) had a screening mammogram 25 or more months before being diagnosed; this group included 65 women (6%) who had never had a mammogram

The researchers compared the characteristics of the breast cancers in each group, as well as the types of treatments the women received.

The researchers found that compared to women of the same age who had had a screening mammogram in the last 2 years, women ages 40 to 49 who had never had a mammogram were more likely to:

  • have larger breast cancer tumors
  • have positive lymph nodes
  • be treated with chemotherapy
  • have axillary lymph node surgery (instead of sentinel node surgery)
  • have mastectomy (instead of lumpectomy)

“We thought it particularly important to focus on this age group because it’s for women in their 40s for which the guidelines have been pulled back and are most confusing,” Dr. Port continued. “Cancers tend to be more aggressive in those younger patients.”

Overall, women who had a screening mammogram within 2 years of diagnosis and had surgery as the first treatment had smaller cancer tumors compared to women who had not had a screening mammogram within 2 years of diagnosis. Women who had never had a mammogram had the largest tumor size.

All these differences were statistically significant, which means they were likely due to the frequency of the screening mammograms and not just because of chance.

“This concerns me as a clinician, because patients are getting such mixed messages,” Dr. Port said in her interview with Schattner. “There’s not just a survival advantage to screening. There’s potential for less treatment. Women need to know this. Besides discussing the lower likelihood of surviving, we need to be talking about the risks of needing more treatment when we discuss whether or not to do mammograms.

“The guidelines vary, and it's confusing,” she continued. “A lot of the guidelines are about weighing costs and harms. But the current approach may be penny wise, pound foolish. I worry that the costs will blow up later, with more money spent and more toxicity. More women will be needing more chemotherapy and more extensive surgery. Without mammography, the personal harms go up of having larger tumors, greater risk, and more treatment. Screening is an opportunity. Screening is the only way we have to intervene to get the tumor before it needs more extensive treatment.”

At Breastcancer.org, we believe that a woman’s best chance for early detection requires coordination of our current screening tools:

  • high-quality mammography
  • clinical breast exam
  • breast self-exam

To not use all three tools are missed opportunities for early detection.

The reality is that every woman is at risk for breast cancer, and this risk tends to increase over time. It’s important to understand and regularly update your health information related to breast cancer risk throughout your life with your doctor. To get the conversation started, here are some points to talk to your doctor about:

  • family history of breast or other related cancers (ovarian, melanoma)
  • any test results for abnormal genes linked to a high risk of breast cancer
  • results of past breast biopsies, even if they were benign
  • personal history of being treated with radiation to the face and/or chest before age 30
  • breast density
  • weight, if you’re overweight or obese
  • level of physical activity
  • any use of postmenopausal combined hormone replacement therapy (HRT)
  • alcohol consumption, if you regularly drink more than 3 alcoholic beverages per week
  • the amount of processed food and trans fats you eat
  • your smoking history
  • whether or not you had a full-term pregnancy or breastfed

Breastcancer.org stands by its recommendation that all women have mammograms annually starting at age 40, and the results of this study strongly support that recommendation. We also believe that monthly breast self-exam and annual physical exams by a doctor are essential parts of an overall breast cancer screening strategy. If you’re at high risk for breast cancer, you should talk to your doctor about starting annual mammograms at a younger age and consider other screening tools (such as MRI or ultrasound) to maximize the opportunity for early detection.

For more information on mammograms, including where to get one and the benefits and risks, visit the Breastcancer.org Mammograms page.


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