In September 2011, I was interviewed for an article in the hospital magazine about mammograms, in preparation for Breast Cancer Awareness month in October. The one question I was asked that stuck out in my mind was, “What is you want readers to know about mammograms?” My immediate answer was, “They are not perfect.” Somehow that was not really explored in more detail and the point never really made it into the article. I guess it might have discouraged women from getting mammograms.
Do mammograms save every woman with breast cancer’s life? Unfortunately not. As Peggy Orenstein in her recent article suggests, many women are under the misconception that if you have mammograms every year, it will save your life. It can, but it does not necessarily mean that it will. But just because it is not a perfect test, does it mean that it should not be utilized at all? The media isn’t questioning the value of pelvic exams, prostate exams and colonoscopies and they are not perfect. Patients are subject to false positives, false negatives and risks of procedures that result from those tests. And, people are still dying from ovarian, prostate and colon cancer.
Do I believe that mammograms save women’s lives? Absolutely. I can for sure say that there are young women’s lives who have been saved by mammography. The problem is that people have been made so aware of how mammograms have helped save lives, that not much has been discussed about the limitations of mammogram until recently. As a result, people have lost faith in mammography. However, if you understand the limitations in addition to the benefits of mammography, you can then choose how to best utilize it in screening yourself for breast cancer.
So what should you know about mammography other than it can save your life?
1. Mammography is limited in dense breasts. This point has been brought up in the media for a while now. To understand in simple terms how the density affects mammography interpretation, see my blog “Breast Density and What Does It Mean?”
2. Mammography is not always able to image the entire breast. The vast majority of breast cancers occur in the upper outer portions of the breast and so the views taken favor imaging those portions of the breasts. However, the lower inner portions of the breast tend to be more difficult to image and as a result, some cancers that develop in the very inner and lower portions of the breast may not show up on mammography. In general, the parts of your breasts that are the closest to your chest and farthest from your nipple can be difficult to image as it is difficult to pull every inch of your breast tissue into the machine.
3. The radiation dose of mammography is fairly low. The dose of one mammogram is equivalent to seven weeks of radiation you get from natural sources in the environment. The dose of a CT of your chest is equivalent to 10-25 mammograms. The lifetime attributable risk of fatal radiation-induced cancer from mammograms is 1.3 to 1.7 cases per 100,000 women. You have a greater chance of dying from a car accident (1 in 84 as quoted by the NY Times) but most people don’t even think twice when getting into their cars.
4. Not every mammogram reading is equivalent. The number of false positives and negatives can vary depending on who is reading your mammogram. The readings can also vary depending on how many comparison mammograms the radiologist has.
5. Some breast cancers are just plain difficult to see on mammography, even on easy to read mammograms. The growth pattern can make some cancers easy to see and others not. If the cancer grows along the breast tissues, as true of lobular type breast cancers, it can blend in with the normal breast tissue and be difficult to detect on mammograms. These types of cancers tend to be larger by the time they are detectable by mammography. However, if the cancer starts to distort the tissues around it, those changes tend to be more easily seen on mammograms, even dense ones.
6. Some breast cancers grow too fast to be detected at a small or early stage. I have seen a perfectly clear mammogram one year and the next showing a large cancer that has spread to other parts of the body. I really hate those cases. I always ask, “What could’ve been done differently?” Unfortunately, we can’t assume that because your mammogram is good today, you will be fine until you get your next mammogram. Cancer can happen anytime.
So, what does this mean for you?
1. Decide first if you want to be screened for breast cancer and at what stage you want to find your breast cancer. Often DCIS (see my blog about DCIS) and sometimes very small invasive cancers are only seen on mammography. Ultrasound tends to find breast cancers after they have formed a mass (i.e, become invasive). If you want a chance at finding your breast cancer early, then have a mammogram done. Remember that the cancers in women who are not in menopause (50’s and younger) tend to grow faster and be more aggressive than the ones that show up in those who are in menopause.
2. If you decide on having a mammogram done, find out if that is enough when it comes to imaging studies. If you have dense breasts, an ultrasound may indicated as an additional means of screening. If you have a high risk or strong family history, MRI may be indicated for screening. Talk to a radiologist whenever you can to find out what imaging tests are best for you.
3. Always feel your breasts, particularly in the areas farthest from your nipple. THIS IS VERY IMPORTANT, for several reasons. First, feeling your breasts allows the areas that can be missed on mammography and even ultrasound to be checked. Second, it allows your breasts to be checked between the yearly mammograms should something grow in that interval period. Third, no one is going to know your body better than you. You are going to be better at finding that breast cancer than your doctor if you regularly check your breasts. (Blog to follow about self breast exams…)
4. To reduce the false positives and negatives, be consistent. Screening works the best when you have a timeline. Get a mammogram done every year to reduce the chances that something might get missed. Always have your prior films for comparison as it reduces the likelihood that you will get called back for additional imaging and helps the radiologist appreciate any change that might be significant.
5. Have a breast radiologist read your mammograms. The more mammograms someone reads, the better they will be at knowing what is normal and what is abnormal. Also, radiologists who perform biopsies get feedback after getting the results, thus learning what varying forms cancer can present as.
The problem with breast cancer screening is that everyone’s breasts look different and not every breast cancer acts or presents the same way. It’s hard to have a “one size fits all” approach. Mammography is not perfect but the things listed above can help overcome its shortcomings and improve detection of breast cancer at an early stage. If you don’t do mammography, what are you left with? You are left with waiting until you develop a mass, or invasive breast cancer. The larger the cancer, the higher the risk of it spreading to other parts of your body. That’s the risk of not doing mammography.
As you will find on my blog, my philosophy is that the patient always has a choice. Just be properly informed of the risks and benefits of the choices you have. Don’t be afraid to ask what your options are. It is your body and ultimately you are the one who has to live with the decision you make, not anyone else.
Stay tuned for upcoming posts about self breast examination, breast MRI and ultrasound.
Mammo Doctor, Mother, Wife - Trying to put it all together... 
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Why no mention of overdiagnosis? Shouldn’t you be HONEST about benefits and risks?
I am being honest about everything I write in this blog. The point of this particular post was to let women know that there are limitations to mammography. Limitations that not everyone is willing to openly admit, which I think has done a disservice to patients and to the value of mammography as a whole. While I encourage women to get mammograms, I believe that every woman has the right to do whatever they want with their body as long as they know what the possible consequences of their decisions entail.
Do I believe there is overdiagnosis? Absolutely. If you want to know about how I feel about overdiagnosis, you should read my blog on DCIS, which is where the argument about overdiagnosis lies. The issue with overdiagnosis is that there is no clear cut line to determine when something is overdiagnosed. Clearly we know that there are some forms of DCIS/cancer that may never kill someone. The problem is we often don’t know which ones will and which ones won’t.
Now if you are referring to the “unnecessary” biopsies or extra pictures that people go through because of having mammography, I would tell you that it depends on the who is reading your mammograms. There are some people who biopsy everything that they cannot be sure is benign (radiologist #1). There are others who only biopsy things that they are sure are benign (radiologist #2). Radiologist #1 will find more cancers but put more people through benign biopsies. Radiologist #2 will put less people through benign biopsies but will miss some cancers. Who is better? Where do you draw the line between the two?
I believe the benefits of mammography, in general, are great. The harm in having a mammogram is low, as long as it is approached reasonably (and that is the key) by both patients and doctors.