Breast Cancer Screening with Mammography: Sorting Hype from Fact

December 30, 2015
Julie Longlet, ASCO staff

Screening for breast cancer with mammography continues to make headlines. Mammography is a type of x-ray that can find breast cancer. Many organizations have different recommendations for women about when to start and stop getting mammograms and how often to get one. To better understand what people should know about mammography, Lineagotica talked with Constance (Connie) Lehman, MD, PhD, Professor of Radiology, Harvard Medical School and Massachusetts General Hospital and Director of Breast Imaging at Massachusetts General Hospital.

Q: Let’s begin by defining screening for breast cancer.

A: When we are talking about breast cancer screening, we are talking about healthy women with no breast symptoms, such as a lump, thickening, or pain in a certain spot. Also the guidelines for mammography tend to focus on women at average risk for breast cancer. Recommendations are not the same for women with symptoms or for women who are at high risk for breast cancer.

Q: To the average person, it seems like every group has different recommendations. Are there definitive areas of agreement? If so, what are they?

Dr. Lehman: Yes, there are clear areas of agreement, and these can be lost in the discussion surrounding mammography. These include the following:

  • Screening for breast cancer with mammography saves lives.

  • Although mammography is an imperfect tool, it is the best one we have to find cancer in women at average risk.

  • At an absolute minimum, women should begin screening mammography no later than age 50 and get a mammogram every 1 to 2 years until at least age 74. All medical organizations agree with these minimum recommendations for screening.

  • If we screened all the women described in the last bullet, we would change the face of breast cancer in the United States. Unfortunately, many women do not receive routine screening and do not have the benefits of early detection.

Q: What are the gray areas of breast cancer screening recommendations?

Dr. Lehman: The areas of disagreement, and reasons for differences in the recommendations from different groups, center around the age to begin screening (40, 45, or 50) and the interval of screening (every year or every 2 years). These variations are due to different groups of people who interpret clinical trial data differently.

Q: Can you tell us more about how doctors and health care researchers can interpret the same data differently?

Dr. Lehman: Some people put more emphasis on the risks of screening, which is primarily the possibility of false positive exam, which could lead to additional imaging, or an unnecessary biopsy or surgery. Others put more emphasis on the benefits of mammography, which is finding an early-stage cancer when treatment options are better for the patient and chance of cure is highest.

A false positive means that the test shows evidence of cancer when there is, in fact, no cancer present. If there is a false positive, a woman may need to go for a follow-up mammogram. In the best case scenario, the areas of suspicion are resolved during the follow-up test. At worst, a woman may need to go for follow-up mammograms, one or more biopsies, and potentially a surgical excision of the suspected tumor to confirm or rule out cancer over a period of weeks or months. During this time, she may be anxious about the possible results and receive unnecessary invasive tests. Although the frequency of false positives is higher than we want, technology is improving rapidly and the newest methods of mammography with tomosynthesis (see next question below) can reduce false positive readings.

It is important to note that patients themselves place different emphasis on the risks and benefits as well.

Q: Please talk about the role of technology when evaluating mammography studies.

Dr. Lehman: The gold standard for changing clinical practice is the randomized clinical trial (RCT). However, large, randomized clinical trials where we have the most data were done at a time when the technology was not as advanced as today. For instance, almost all mammograms today are digital and not film, but the RCTs were performed on film mammography. Digital mammography is more accurate for many women.

Many breast centers also use tomosynthesis. This technique takes x-rays of the breast from different angles so the doctor has multiple “slices” of the breast, similar to a CT scan. When there are many more views of the breast, it is less likely that you will get a false positive result. If I see something suspicious in one image, I can scroll through multiple images to find out if what I’m seeing is actually a real lesion.

Q: You mentioned women in their 40s being a gray area for screening. What are some questions women in their 40s should ask their doctors about mammography?

Dr. Lehman: First, women need to learn whether they are high risk or average risk, because this changes the calculation. If there is a history of breast cancer in your family, even on your father’s side, you may not be at average risk. So, the first two questions are:

  • What is my breast cancer risk?

  • What screening program is best for me?

Then, women need to have a frank discussion with their physicians about their goals for their health. If a woman values early diagnosis and treatment, then I would encourage her to start screening at age 40, for example. It is important for women in their 40s to go to a high-quality radiology center that has tomosynthesis and specialized breast imagers interpreting the exams.

Q: What else should women know about mammography?

Dr. Lehman: Besides their risk, women should be screened at an accredited center. Under the Mammography Quality Standard Act, all facilities that bill for mammography must be accredited. This means that an accredited, external group has evaluated the tools and methods used to ensure a safe, consistent mammography experience and accurate interpretation of the mammogram.

With the Affordable Care Act, women are able to get screening mammograms with no co-pay or deductible. This is a fantastic provision that can save lives.

Q: Are there other topics or questions surrounding mammography that need to be addressed here?

Dr. Lehman: There is a lot of confusion around breast density. Many states have passed legislation to notify women if they have dense breasts and the letters women receive can be alarming. If you are worried about breast density, talk with your doctor or radiologist.  Dense breast tissue can increase the chance of having a cancer missed by mammography and can increase slightly a woman’s risk of breast cancer. However, unless a woman is truly at high risk (beyond dense breast tissue alone), very few medical groups support adding either MRI or ultrasound as screening tests to supplement screening mammography.