New practice guidelines were just suggested for mammograms by a public health task force. (In addition, another task force just suggested changes in the use of Pap smears. We will comment on that issue separately.)
These guidelines sharply cut back established recommendations for breast cancer screening in women, contravening policies updated earlier this same decade by the same group. Many professionals and women are appropriately confused. How do we respond?
Breast Cancer Screening: Task Force “Guidelines”
The public health task force guidelines conclude that for most women in their 40’s the benefits of mammograms are not worth the risk of anxiety, biopsies and possibly inappropriately aggressive treatment of very early cancers. For women 50 and over, the new guidelines suggest the frequency of mammograms should be every 2 years rather than annually, and that the benefits of mammography for women over 75 are unproven. The task force also saw no proven value in breast self-exam nor in examinations by a physician. But they suggest each women’s relative risk should be evaluated by and discussed with their physician.
Breast Cancer Screening: Key Points
We find the task force analysis to substantially change current practice to be unconvincing, as does the American Cancer Society and many other professional organizations. But like many issues in medicine, the facts and issues are complex and often a bit fuzzy. Some points to consider:
- Screening for breast cancer becomes progressively more effective as women age because the disease is more likely and the imaging techniques are more effective in older women. We all agree on that.
- Breast cancer screening is a biological continuum, with screening mammograms most productive in women in their 60’s, less so in their 50’s, and even less so in their 40’s — but lives are saved by screening. The differences are relative only, and the differences not that dramatic.
- Mammogram screening is about 40% less effective in women in their 40’s compared to those in their 50’s, while screening is about 4 times more effective in women in their 60’s than in their 50’s, all based on the number of women who need to be screened to identify one case of cancer. No one is suggesting screening only women in their 60’s. The rationale to stop screening women in their 40’s is truly unclear and unconvincing.
- It is difficult to determine which women are truly high risk at any age. Certainly strong family history and known genetic predisposition matters, but the majority of new cases of breast cancer occur in women who are not obviously high risk. That is one of the rationales for screening and not targeted testing. No matter how much you talk with your doctor, your doctor cannot know the unknowable or unknown. However, be clear that neither the task force nor any other professional is recommending reducing mammogram or other imaging surveillance of any woman known to be high risk for breast cancer.
- Structured breast self-exam has been carefully evaluated and appears to offer little independent benefit of early detection of breast cancer. So women can be freed of guilt of not doing, each month, yet another task. But paying attention when you wash yourself in the shower has no downside. And every physician must pay careful attention whenever a women feels she has felt something different or abnormal in her breast.
- Breast exams by your doctors are a sensible part of a regular general exam, although they may not have enough independent cancer detection value to warrant a separate visit just for that purpose (which is rarely the case in usual clinical practice).
- Because a high proportion of new cases of breast cancer occur in women without obviously high risk, detailed individual evaluation by your personal physician may not be able to refine the risk very much for most women. Hence the importance of sensible general practice guidelines that are evidence-based but not arbitrary.
Breast Cancer Screening: Our Outlook
We in general support the current practice of offering mammography to all women after age 4o, but we should reflect carefully upon a number of issues raised by the proposed new guidelines:
- We support annual mammograms for women in their 40’s. However, given the known lower effectiveness of mammography in younger women, the “annual” standard may be overly aggressive and the earlier standard of getting a baseline in the early 40’s and then every few years until age 50 may be entirely sufficient. This issue will be discussed individually.
- We support annual mammograms for women from 50-75. However, given the apparent small benefit of annual compared to biannual mammograms for these women, a slightly longer time-table between exams for apparently low-risk women could be entirely reasonable. Remember, effectiveness is a continuum, so small time differences make at most small differences. Annual exams were only about 20% more effective than biannual, so a rigorous 12-month and not a day longer schedule is not really warranted.
- For women over 75, with no proven benefit for mammograms at all, no less for annual screening, we support continued mammography but most likely a more relaxed schedule is entirely reasonable. Remember, biologically tumors grow less quickly in great-grandmothers, so the need to check with imaging is less pressing.
- We believe breast exams are an important part of your annual physical. Careful exams are effective in finding abnormalities, even if not so effective as mammograms. Similarly, we believe and practice that an undressed, careful physical examination of your body by your doctor is an important tool for data-gathering and to provide biological solidity to our evaluation, recommendations, and reassurances for you at those visits.
Further Issues on Breast Cancer Screening
Breast cancer, like much of human biology, is immensely complex. We know much more now than we used to, but still too little. Consider just the following two related issues:
- Breast cancer imaging techniques, while much better than two decades ago, are still only partially effective. We need to pay careful attention to the evolution of other imaging techniques, such as MRI, that may ultimately increase the effectiveness of screening in younger women. A large part of the current debate on frequency and timing of screening reflects the relative ineffectiveness of current technology in this age group. Improved detection techniques (whether by imaging or immunology or other) will certainly radically change this discussion.
- The task force’s concerns about overtreatment from mammograms relates to DCIS. Some of the tumors detected largely by mammography are pathologically called DCIS (ductal carcinoma in situ), which is a precancerous lesion that often but not always evolves into an invasive cancer. Unfortunately, we cannot now tell which particular DCIS tumor will be dangerous nor in what time period, nor distinguish it from one that may not evolve or may even disappear. The current decision rule has been to treat most of these DCIS cancers pretty much the way one would treat an invasive cancer. This is what gives rise to the task forces’ concerns about possible overtreatment produced by mammograms, since DCIS is unlikely to be detected by the woman or her physician on physical exam. Without better understanding of the biology of DCIS, we are hard put to improve on the decision of active treatment, but certainly some women are being treated unnecessarily, if we only knew which ones. (There are analogies with early detection of prostate cancer by the PSA test, incidentally, and the very same therapeutic dilemma.)
The breast cancer screening discussion has only just begun with the publication of the task force’s new guidelines. You have seen the waves of commentary by public health and governmental figures, not to mention the physician community. The fallout will continue at least for weeks, probably longer.
We hope this discussion has been useful to you. We may publish an updated commentary later this year if the robust professional discussion that is underway truly offers enlightenment that should be offered to you. We will comment on the Pap smear guidelines later this month.