The U.S. Preventive Services Task Force (USPSTF) has drafted new guidelines for breast cancer screening. In its first review since 2009, the government-sponsored panel found that mammography’s benefit is real but small for women 40 to 49 years, warranting a “C” recommendation and advice to women to make individualized decisions. For those between 50 and 74 years, the USPSTF recommends screening biennially rather than each year.
My greatest concern is the lack of firm advice for women in their forties to get screened. If you consider the long-term benefits of finding invasive cancer early, it is younger women who have the most to gain. Why mammography matters is not 5-year survival but how those affected live 10, 15, 20 and even 25 years beyond.
The panel’s C recommendation lessens the likelihood that women under 50 years will be encouraged to get mammograms. It opens up the possibility that insurance will not cover their screening. According to its mandate, the USPSTF does not take costs and insurance issues into account when it assesses evidence for screening and preventive services. The ACA requires coverage of preventive services with “A” or “B” recommendations (mammography is not preventive, in any case). This crucial issue needs be clarified by Health and Human Services.
The wishy-washy advice is a disservice to women’s health. Despite progress, breast cancer remains a major cause of illness among middle-aged women. Each year some 40,000 succumb to this disease, amounting to nearly 110 deaths every day in the United States. Mammography is not just about saving lives: Early detection affords most women with invasive breast cancer the opportunity to choose smaller, potentially curative surgery and a lesser, finite course of treatment.
The panel erroneously presents low calculations of mammography’s benefit, in terms of deaths averted (said to be 4 per 10,000 women screened), by re-analyzing the same old studies. Given that breast cancer is a leading killer of women in their forties and fifties – and meanwhile rates of invasive cases have been rising – the number of deaths averted by early detection and careful intervention may be much, much greater than the old trials suggest.
In some respects the panel offers a sane perspective. It acknowledges the lack of modern data to inform today’s recommendations. The group correctly notes that most relevant mammography trials are over 30 years old. But the proposed guidelines are weak where they should be strong, chiefly because the task force underestimates screening’s value and overestimates harms for middle-aged women.
My second concern is that the panel exaggerates harms of screening, and overtreatment in particular. The group cites crazy-high estimates of false positive tests, 90 percent of which are call-backs for additional imaging. A much smaller fraction – 10 percent, over ten years of screening – of women get a false positive involving biopsy, according to the data the panel cites. In modern radiology practices, the number of call-backs should be much lower and for false positive biopsies, lower still.
More importantly, the USPSTF ignores progress in pathology which enables doctors to avoid over-treatment. In a supporting Q&A document, the task force states: "Currently, it is not possible for a woman to know whether or not her cancer will progress.” While it is true that a woman and her doctors can’t be 100 percent sure about one tumor’s tendency to grow and spread, there are plenty of non-experimental ways to assess the likelihood a cancer's causing harm. These include now-standard molecular profiling tools like OncotypeDx, which is covered by most insurance, and the FDA-approved MammaPrint, and other assays. The USPSTF, which lacks a cancer specialist, radiologist, surgeon or pathologist, mentions none of these ways to distinguish indolent from dangerous tumors.
The biennial recommendation makes sense to me. This strategy essentially halves the costs and risks of screening without significantly lowering the pick-up rate for most invasive breast cancers types. But there’s one major caveat. The screening, especially if it’s done every other year, should be performed strictly by breast imaging specialists, radiologists who do only this. All doctors who interpret mammograms should be experienced and knowledgeable in supplemental imaging procedures, should those be needed to evaluate abnormalities or cloudy mammograms in dense breasts.
The panel said that evidence for new and supplemental imaging methods including MRI, tomosynthesis (3-D mammography) and ultrasound, the evidence is inconclusive (“I”). This is a fair statement, based on the lack of randomized trials for these new tools. But I do think emerging data for ultrasound are quite encouraging. Also worth mentioning and off the task force’s radar are yet newer, low-dose molecular breast imaging (MBI) methods that, in early published studies, suggest improved accuracy for detecting invasive cancer in dense breasts.
The task force was right to offer an “I” (inconclusive) recommendation for screening women over 75 years. It’s not that older women don’t benefit from mammograms; they may indeed, especially if they are in otherwise good health and unlikely to otherwise die within a few years from something else. Also, breast cancers tend to be more slow-growing in the elderly. If overdiagnosis of invasive cancer does exist, which I question, the concept would apply mainly to those over age 70. As I have written previously, the concept of overdiagnosis of invasive tumors doesn’t apply to young and middle age women.
As far as noninvasive and stage 0 tumors like ductal carcinoma in situ (DCIS), the task force appropriately calls for more research. But that shouldn’t diminish its clear recommendations and how we think about finding and managing frankly invasive breast cancers.
Finally, the push for individualized decisions in younger women sounds great, modern and politically correct. It supports the need for grants and research to aid women and their doctors in assessing risk, popular charts and pseudo-informative brochures, and a sense of empowerment. But officials' indecision in medicine can reflect a failure of responsibility. After all, the USPSTF makes recommendations on all sorts of screening, such as for HIV and hepatitis C, and for mammography in older women. In this context, why hesitate to recommend breast cancer screening for women in their forties, who have so much to gain?
Today there are good reasons why an oncologist, or advocate as I am, might recommend mammography for women between the ages of 40 and 65 years. That’s in part because breast imaging and diagnostic tools have steadily improved over 20 years, rendering screening safer and more accurate than ever before. No doubt, mortality from breast cancer has declined since the late 1990s, by around 35 percent. A significant fraction of the improved survival must be attributed to early detection and smart management of early-stage disease.
What’s presented by the USPSTF today is intended as a draft, open for public comment prior to formal publication. I do hope that its recommendations for screening might be strengthened and include a modern view of oncology, and clearer advice for women and primary care physicians about the current benefits and safety of breast imaging for cancer screening.
