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The Final (???) Word on Screening Mammography

17 January 2016

In October 2015, the American Cancer Society (ACS) updated their screening mammography guidelines, raising a lot of questions and concerns as annual mammograms were no longer recommended for all women starting at age 40. The United States Preventative Services Task Force (USPSTF) released new guidelines on screening mammography last week. The new USPSTF guidelines recommend an individualized risk-based approach for women age 40-49, and mammographic screening every other year for women age 50-74. The task force acknowledged that screening mammography reduces the likelihood of dying from breast cancer, but noted that the benefit was the greatest for women age 60-69, and the benefit was small for women age 40-49. For younger women, they noted that screening mammography is associated with higher false positives (false alarms).

The conflicting guidelines published by the USPSTF, ACS, and other organizations have caused much confusion. Many women simply want to know what they should do. The reality is, screening mammography is a one size fits all tool, and as any woman knows, that doesn’t really work. The sensitivity (“effectiveness”) of mammograms will vary depending on a patient’s age, menstrual status, use of hormone therapy, body mass index, breast density, and other factors. It is unrealistic to expect that one test can account for all of those variables, as well as personal risk factors for breast cancer, and personal preferences regarding screening risks and benefits.

To state it very simply:

  • Mammograms may lead to improved survival from breast cancer by detecting some cancers early
  • Some breast cancers are so aggressive that early detection does not lead to improved survival
  • Mammograms are imperfect

It is important to note that the USPSTF and ACS recommendations apply to average risk women. Unfortunately, risk assessment is not routinely performed, and many factors associated with an increased risk, such as heavy alcohol intake and breast density, are not taken into account in the existing models. In an ideal world, we would swab a cheek, obtain some DNA, and then determine whether or not a woman is predisposed to develop breast cancer [I’m thinking beyond BRCA and other genetic testing here]. If we can determine that a 30 year old woman, even without a family of breast cancer, is predisposed to develop the disease, we can make educated screening recommendations (perhaps ultrasound and/or MRI, as mammograms are not very helpful in very young women).  If we can determine that a woman is highly likely to die of a heart attack by age 60, and has no cancer predisposition, she might make the decision to forego screening mammography. Unfortunately we’re not quite there yet, but there are genetic risk tests under development.

I recently spoke with a researcher specializing in cancer risk. We discussed that at the end of the day, multiple organizations will continue to look at the evidence and draw different conclusions, so in his opinion, it wasn’t realistic that we should expect consensus. Physicians, researchers, and organizations are currently spending a lot of time and effort arguing with each other about whether mammography should start at age 40, if mammograms should be performed every versus every other year, and when screening should stop. However, our time and efforts might be better spent by working together to address issues such as disparities in access to screening mammography and lack of access to quality mammography and breast care for many women.

Recognizing the variability of each woman and her breasts, acknowledging the uncertainties regarding the risks and benefits of screening, and focusing on a shared decision making approach might help reduce some of the confusion. In medicine, as in many areas in life, there is often more than one right answer. The same applies to screening mammography. Time to move beyond the one size fits all approach.

Additional Reading:
New York Times: Panel Reasserts Mammogram Advice
JAMA: A Public Health Framework for Screening Mammography: Evidence-Based vs Politically Mandated Care 
New York Times: Insurer Rewards Push Women Towards Mammograms
Forbes: A Turning Point in the Breast Cancer Screening Debate?
NPR Shots: Federal Panel Finalizes Mammogram Advice That Stirred Controversy
OncLive Final USPSTF Guidelines
Cornell Mammogram Decision Aid for Women age 40-49

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Are False Alarms Cause for Alarm?

5 December 2015

Approximately 60% of women undergoing annual screening mammography over a 10 year period will be called back for additional views. Often these are in women with dense breast tissue, which can make it more challenging to read mammograms. Many of these callbacks are false alarms, also known as false positives – the abnormality may resolve with additional views, it may be found to be a benign lesion (such as a fluid filled cyst), or a biopsy may be performed and the pathology is found to be benign.

In a study published in the journal Cancer Epidemiology, Biomarkers, and Prevention, researchers found that false positive mammograms are associated with an increased likelihood of eventually developing breast cancer. Using data from the Breast Cancer Surveillance Consortium, they noted that women who had a false positive mammogram with additional imaging or biopsy recommendation had a higher likelihood of developing breast cancer compared to women with a normal mammogram. For every 1,000 women who had a true negative mammogram, 3.9 developed breast cancer over a 10 year period (average follow up 5.4 years). For those requiring additional imaging, 5.5 / 1000 developed breast cancer over 10 years, and in those who underwent a biopsy 7 / 1000 eventually developed breast cancer. It is important to note that the absolute risk of developing a breast cancer in the case of a false positive mammogram was very low – less than 1%.

The group of women with the highest rate of breast cancer development were those with dense breast tissue who underwent a biopsy. This is not surprising, as we know that breast density increases the risk of breast cancer, and the number of prior breast biopsies is factored into risk assessment models such as the Gail and Tyrer-Cusik models.

At this point, it is not recommended that women who have a false positive mammogram undergo any specific additional imaging such as MRI (unless recommended based on the mammogram). A false positive mammogram is one risk factor, but it needs to be evaluated in the context of other breast cancer risk factors, such as increasing age, family history, obesity, and alcohol intake.

Additional Information:
Dr. Margaret Polaneczky blog post
Breast Screening Decisions – screening mammogram decision tool for women age 40-49
ASCO Post Commentary
NPR False Alarm Mammograms
HNR False Positive Mammograms and Cancer Risk

 

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New Patient Information Website

 

9 November 2015

The American Society of Breast Surgeons Foundation has just launched a patient information website – Breast360.org. The site was developed by breast surgeons, and patient advocates have had input and oversight during the entire process. Please take a look, and feel free to provide feedback if you have a suggestion for additional content.

 

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Do I Need a Mammogram?

17 February 2014

Spoiler alert – this will hardly be the last word on the screening mammography debate…

Last week, the British Medical Journal published a Canadian Study which concluded that mammograms are not effective in reducing breast cancer deaths. The study involved 90,000 women. However, there are some major flaws in the study, and “rapid response” letters to the editor were published within hours of the study release. So while the headlines scream “mammograms are not helpful”, the study is in question and it may not be possible to draw this conclusion.

While previous randomized trials have shown a reduction in breast cancer mortality due to screening mammography, there is no doubt that mammography is far from perfect. We have to screen a large number of women to diagnose one with breast cancer. In doing so, a percentage of women will require additional imaging and/or will undergo a needle biopsy for a benign finding. Mammography is not as helpful in younger women and in those with dense breast tissue. In addition, as technology has improved to allow us to see through the breast with more detail, we are diagnosing cancer (and precancerous conditions) that may never become a threat to a woman’s life.  We are trying to find the balance between early detection which often (but not always) leads to improved survival, versus over diagnosis and over treatment.

Part of the problem is our technology. The results of screening mammography are highly variable depending on the patient’s age, breast density, weight, use of hormone therapy, and other factors. We have a one-size-fits-all test, which as every one knows, is really one-size-fits-none. We are also limited in who we screen. Women younger than 40 without a family history of breast cancer have no routine screening recommendations, and mammography is not very helpful in this age group. Many will use this as an argument for the use of ultrasound or MRI examinations. While these modalities may be extremely helpful in a given patient, they have not been proven to be effective in reducing mortality from breast cancer when applied to a general screening population.

It is important to realize that we have an imperfect technology, and our application of that technology to the individual is also imperfect. More research is needed to determine who is actually at risk, and who will truly benefit from screening. In addition, screening needs to be more individualized – a mammogram is not the right screening tool for all. Dr. Peter Beitsch, Past-President of the American Society of Breast Surgeons, has said on many occasions that “female and 40 is no longer acceptable for screening mammography – we need to risk assess each woman individually and use appropriate breast imaging tailored to them.”

In addition to more individualized screening, research is needed into which cancers even need to be treated. Many breast cancers found on mammography may never become a threat to a woman’s life. However, a hallmark of cancer is cell mutation – the slow-growing cancer today may not behave that way in the future, so at this point we err on the side of over treatment, as we cannot reliably predict future biologic behavior. Dr. Robert Miller, a medical oncologist who the Senior Director, Quality and Guidelines and Medical Director, CancerLinQ, at the American Society of Clinical Oncology, stated that “we simply can’t tell if early breast cancer diagnosed by mammogram will be indolent or not. For the individual patient we can’t say it’s ‘over diagnosis’. ”

And that’s really the bottom line. For an individual patient, we do not always have the right answer – our science and technology are just not there yet. While this is frustrating for many patients as well as for physicians, it is exciting to be practicing in a time when we are making progress (albeit slow) towards more individualized screening and treatment recommendations.

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