New Mammogram Guidelines — My 2 Cents

In case you didn’t hear, the world ended last week. No, I’m not talking about the film “2012.” I’m talking about the latest guidelines from the United States Preventive Task Force (USPSTF) on breast cancer screening.

The guidelines, which came out early last week to much fanfare, make two major changes to the previous USPSTF recommendations from 2002. One, the task force recommends that routine screening for breast cancer begin at age 50, rather than age 40. Two, screening should occur every two years, rather than every one to two years.

My 2 cents are that 1) the change is not as major as we are being led to believe and b) the change is in the right direction because it recognizes the limitations of mammography in younger women and increases individualized decision-making.

First off, how significant is this change in guidelines? While many women are accustomed to the idea getting mammograms every year starting at age 40, we have known for some time that the data supporting screening in women ages 40-49 and screening every year are limited. In fact, in the previous guidelines, while the USPSTF recommended screening beginning at age 40, it noted that the “precise age at which the benefits from screening mammography justify the potential harms is a subjective judgment and should take into account patient preferences.” While studies have shown that mammography in women ages 50-69 reduces deaths from breast cancer by about 33 percent, most studies in women ages 40-49 have shown no mortality benefit. Although pooling all these smaller studies together shows a 15 percent decrease in deaths, this must be weighed against the increased risk of false positives, unnecessary biopsies, and treatment of cancers that if left alone would not cause any harm. In terms of screening interval, the previous guidelines wrote, “In the trials that demonstrated the effectiveness of mammography in lowering breast cancer mortality, screening was performed every 12-33 months… there is little evidence to suggest that annual mammography is more effective than mammography done every other year.” Thus the previous guidelines recommended screening every 1-2 years, while the guidelines now call for screening every 2 years. Thus the guidelines are a small change from what doctor offices should have been doing — that is, individualized decision-making in younger women and not-necessarily-annual mammograms in older women.

Second, why do I think the new guidelines are better? One of the more sobering facts those of us passionate about preventive health have come to realize is that the benefits of cancer screening have been oversold. Cancer screening, while effective, is limited and certainly no panacea. Even if we increased mammography rates to 100 percent, there would still be lots of breast cancer and lots of death from breast cancer. As described in a recent NY Times article, there are really three types of cancer. The first are cancers that grow so quickly that no matter when we catch them the outcome is the same. The second are cancers that grow so slowly (or even regress) such that we are almost better off not finding them (we’re better off because once found we treat them with aggressive measures — surgery, chemotherapy, and radiation — without any improvement in outcome). And the third are cancers that grow moderately fast and that if found early can be effectively treated and even cured. Unfortunately, with our current state of technology, we cannot distinguish between these three types of cancer at diagnosis. Thus once found, all cancers are treated the same, even though screening and early detection only benefit the third type of cancer.

So part of this change in the guidelines reflects the fact that mammography is imperfect. At the same time, it also reflects the fact that mammograms are not benign procedures. To prevent one death from breast cancer in women ages 40-49, 1900 women would need to be screened for 10 years, of which hundreds would undergo unnecessary biopsies and a few would undergo unnecessary treatment with breast surgery and radiation. It not just the financial cost that makes mammography in lower risk women not make sense. Dollars and cents aside, from a purely patient care perspective, it is not at all obvious that the benefits of screening in the average woman ages 40-49 is worth the harms.

In the end, the guidelines are simply that — guidelines. The USPSTF is not arguing that women should not be screened for breast cancer in their 40s or should not be screened every year. What the task force is saying is that mammograms should not be routinely recommended to women ages 40-49 and should not routinely be done more frequently than every 2 years. Instead, women ages 40-49 should have a conversation with their doctors about screening. In that conversation doctors should explain the risks and benefits of screening, and women should discuss their family history of breast cancer, their risk factors, and their preferences, and come up with a shared decision. (That sounds familiar doesn’t it? Yes, because that’s what doctors are supposed to do with every patient every time for every test.)

What this comes down to then is the word routine. Routine means everybody gets it, that doctors order it without thinking about it, that patients get it without necessarily be explained the full benefits and harms. In busy office practices, this means that patients have mammograms scheduled by office coordinators or nurse practitioners, or by the radiology suite that did their mammogram last year, often without even a word in passing between the patient and the doctor. It also means, in our increasingly quality improvement driven environment, that insurers and the accreditation agencies evaluate doctors based on how many of their female patients over a certain age get their mammogram within the recommended screening interval. Routine is a buzz term for the standardization of a medical service in order to apply it uniformly to a defined population. Put this way, given the data above, mammograms should not be routine in women ages 40-49. Mammograms should not be done uniformly, but rather be an individualized decision, just as the previous 2002 USPSTF guidelines had called for.

If we step back and are honest with ourselves, we would ideally have such a conversation about mammograms in all women we order it for. Mammograms are not a benign procedure and require some explanation and discussion. But the reality of medical practice is that we don’t have the time to counsel every patient about every test we do. Thus we consign ourselves to only consenting patients for those procedures that are out-of-the-ordinary, that are not routine, in hopes that we strike a balance between doing what makes sense for most patients and doing what makes sense for the patient in front of us.

Put in this light, this change in the recommendation for breast cancer screening — from a routine screening in women ages 40-49 to a non-routine procedure — compels us that for the marginal case – a woman in her 40s for whom screening is not the obvious choice — we sit down and have a honest conservation about what makes sense for her. And that I think is never a bad idea.

- Shantanu Nundy, M.D.

USPSTF breast cancer screening guidelines: http://www.ahrq.gov/clinic/USpstf/uspsbrca.htm

NY Times article about the new guidelines: http://www.nytimes.com/2009/11/17/health/17cancer.html?bl

NY Times article about data behind new mammography guidelines: http://www.nytimes.com/2009/11/23/health/23cancer.html?ref=health

NY Times articles about history of mammogram guidelines: http://www.nytimes.com/2009/11/22/weekinreview/22kolata.html?ref=health

NY Times Op-Ed piece, “Addicted to Mammograms”: http://www.nytimes.com/2009/11/20/opinion/20aronowitz.html?sudsredirect=true

My blog post on pros and cons of mammograms: http://beyondapples.org/2009/07/14/the-case-of-the-woman-who-refused-her-mammogram/