A Look at Mammography – 2D vs 3D

The best weapon against breast cancer is prevention and early diagnosis through screening. But at what age should you have your first screening? And what screening exam should you choose?

You may have heard of 3D mammography…when is it the best option? We went to one of our leading breast imaging experts to find the answers. Gopal Vijayaraghavan, MD, director of breast imaging at UMass Memorial Medical Center, offered the information in this blog post. Women who are 40 to 50 years old find conflicting viewpoints in the media and on the web. He says there are three important questions women should ask their doctors about screening.

1. At what age should I start screening?

Most breast cancer in the US occurs in the age group from 45 to 75 years with the peak in the 55 to 64 year age group. But that doesn’t mean younger women are immune.

cancer age chart

A quarter of all breast cancers occur in the 40- to 50- year age group, and most medical societies, like the American Cancer Society and American College of Radiology, recommend annual screening for women in their 40s.

The Comprehensive Breast Center at UMass Memorial also recommends annual screening for women after age 40, and some women at risk may need to start screening earlier. The best advice is to talk with your primary care physician.

2. What screening exam should I choose?

A standard 2D digital mammogram is the current gold standard, and most facilities in the United States perform only these screenings. Digital mammograms are superior to film-screen mammograms, which are being phased out. And now, 3D breast imaging, or tomosynthesis, is getting a lot of attention.

Current scientific literature suggests that this is superior to the traditional 2D mammograms, which has some disadvantages. Look at this diagram below. A small cancer is masked by the normal breast tissue resulting in a false negative interpretation.

breast diagram

In the diagram on the left, normal breast tissue may mimic an abnormality due to overlap, resulting in a false positive test and a call back for additional testing.

In 3D tomosynthesis,
thin slices of the breast are obtained, and breast cancer maskedevaluation of the breasts is like flipping the pages of a book. This makes the examination more sensitive, improving the ability to detect invasive cancers by 15 to 22 percent, and reduces the likelihood of false positive and false negative results. (Breast Cancer Screening Using Tomosynthesis in Combination with Digital Mammography. JAMA 2014; 311 (24)2499-507. Sarah Friedewald et al).

For the patient, the experience of 3D tomosynthesis is no different from getting a standard mammogram – it just takes a few seconds longer.

Compare the two images below. You can see the benefits of 3D tomosynthesis. A small cancer (circled) on tomosynthesis slices in image A (left) is not apparent in the standard 2D mammogram, image B (right) of the same patient and same projection.

3D Mammography image

2D Mammography image

 

 

 

 

 

 

 

 

 3. Are my breasts dense and what should I know?

Breast composition may vary from being essentially fatty to extremely dense. Dense breasts are not abnormal and are generally seen in about 40 percent of the United States population. But dense breasts can mask an underlying cancer, making it difficult for your radiologist to make a diagnosis on your mammogram. In addition, breast density may slightly increase your chance of developing breast cancer.

Many states have mandated legislation that requires a mammography facility to inform women about their breast composition. In Massachusetts, this law becomes effective in January 2015. Also starting in January, women with dense breasts will receive a letter encouraging them to follow up with their primary care provider or mammography center.

UMass Memorial radiologists routinely perform 3D tomosynthesis for their patients with dense breasts. Mammograms are performed at UMass Memorial Health Care hospitals and sites.

October is National Breast Cancer Awareness Month
Join us for a discussion on Thursday, October 30, 6 to 7 pm, UMass Memorial Medical Center – University Campus, about the current understanding of risk factors for developing breast cancer, the latest information on prevention and the effectiveness of screening. Register today.

  7 comments for “A Look at Mammography – 2D vs 3D

  1. Just the facts, please
    October 27, 2014 at 1:52 pm

    I wish this had been more balanced and accurate. The US Preventive Services Task Force (USPSTF) which, unlike the American Cancer Society and the American College of Radiology, is unbiased recommends:
    1) women in their 40’s should learn about the evidence for benefits AND harms of mammography and make their own decisions based on their personal values;
    2) the USPSTF recommends that whenever women do start mammography, they should do it every other year, since harms are almost doubled with annual mammography while benefits are barely increased.

    And is “The best weapon against breast cancer is prevention and early diagnosis through screening” when current evidence suggests regular mammography only decreases the risk of dying from breast cancer by about 15%? The recent Canadian study found NO benefit. Treatment advances have probably made a much greater difference in mortality

    And please keep facts accurate – the NCI says the median age of diagnosis is 61, not mid-50’s (http://seer.cancer.gov/statfacts/html/breast.html). We should be trying to inform, not scare.

    Like

    • December 1, 2014 at 11:00 am

      Thank you for your comments. Our apologies in responding so late. We sent your comments to our expert blogger, Gopal Vijayaraghavan, MD, Director of Breast Imaging at UMass Memorial Medical Center. Here are his responses:

      Regarding your first paragraph: “We realize this is a subject where there has been a lot of debate and polarized opinions and no clear consensus. Comparative Effectiveness Research (CER) should provide evidence on the effectiveness, benefits and harms of different screening options for different patients. Guidelines of new health care reform (PCORI-Patient Centered Outcome Research Initiatives) ensure we involve patients, caregivers, and health care payers to address concerns and disparities. Hopefully, we may have clearer answers in the years to come. I have also clearly stated that the woman should have a conversation with her primary care physician. Opinions of medical societies and USPSTF recommendations are the subject of heated discussion in medical literature. The value of any screening program continues to be questioned due to the increasing cost of health care expenses.

      Regarding your second paragraph: “There is little doubt that along with advances in mammography technology, there have been advances in surgical techniques and medical oncology drugs that have all contributed to a reduction in mortality. In the medical literature, the benefits of screening have varied from 15 to 45 percent. Some of the best documented research – the Swedish trials have claimed 45 percent benefit from screening mammograms (published in Cancer Epidemiology Biomarkers and Prevention). In an article published in NEJM (New England Journal of Medicine), where all compounding factors were considered (hormone therapy and chemotherapy in particular) the overall mortality benefit was around 40 percent (screening accounting for 20 percent, hormone therapy and chemotherapy accounting for 10 percent each). It is obvious that screening alone without quality follow-up treatment will not reduce mortality. Likewise, treatment will be less effective in the absence of screening which picks up smaller and treatable cancers. In general and in radiology literature one of the most criticized trials is the Canadian trial both for the quality of the mammograms and their randomization process. Historically when benefits of screening mammograms are reviewed there are seven common trials quoted. The Canadian trial is one of them. The other six showed benefit except the Canadian trial.

      Regarding NCI comment: “There was no attempt to scare and misinform regarding breast cancer incidence. From this slide from Seer data (see amended blog post), it is obvious that most breast cancer in the US occurs in the age group from 45 to 75 years with the peak in the 55 to 64 year age group.

      Like

  2. Anonymous
    October 27, 2014 at 1:29 pm

    Will UMass soon be able to complete all films including extra views at the time of the mammogram instead of calling women to come back in for extra views? Other hospitals are able to get all films at the mammogram appointment by having a radiologist review initial views.

    Like

    • December 1, 2014 at 8:51 am

      We went back to Gopal Vijayaraghavan, MD, Director of Breast Imaging at UMass Memorial Medical Center to ask this question. His response: “While this is a good suggestion, we will need to look into its feasibility and practicality. UMass Memorial is similar to most academic practices where screening mammograms are ‘batch-read,’ after the patient has left the department. This to date seems the most efficient way to manage given our current resources and large volumes. We are aware smaller private practices are able to provide ‘real time‘ reads like diagnostic services.

      Like

  3. Tom
    October 27, 2014 at 1:14 pm

    Does that mean that the 40% of women with dense breasts will be called back for 3 D mammography?

    Like

    • December 1, 2014 at 8:48 am

      Apologies for taking so long to respond. According to our expert blogger, Gopal Vijayaraghavan, MD, Director of Breast Imaging at UMass Memorial Medical Center, the answer is no. “The relative risk in women with dense breasts (approximately 10 percent of women screened) is X 2, and in women with heterogeneously dense breast is X 1.2 (approximately 40 percent of women screened), when compared to a woman with average to low risk. So the risk in a large percentage of women, with “so called dense breasts” is really small, but will receive a letter as per new mandated regulations in the state of Massachusetts. Additional testing will be based on individual risk profile for breast cancer and decided on a case-by-case basis. Digital 2D mammogram is still the ‘gold standard.’ Additional 3D testing is an option .

      Like

  4. October 23, 2014 at 5:59 pm

    Great read, a lot of really great information here for women. Awareness is the first step to prevention. Thanks for sharing this helpful information.

    Like

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