USPSTF Guidelines: Biennial Breast Cancer Screening From 50

Neil Osterweil

January 11, 2016

Once more, the US Preventive Services Task Force (USPSTF) has issued an update to its 2009 breast cancer screening guidelines, reaffirming that women 50 to 74 years of age are most likely to benefit from mammography, optimally performed once every 2 years.

The guidelines diverge from those of issued by the American Cancer Society (ACS), National Comprehensive Cancer Network (NCCN), and other groups in the recommended age ranges and the frequency of recommended screenings. The ACS and NCCN guidelines recommend that women start mammography in their 40s, and both call for annual screening until a woman has a less than 10 year life expectancy.

The updated USPSTF evidence-based guidelines, a draft version of which was released in April 2015, remain largely unchanged from the 2009 iteration. The final guidelines, along with editorials and supporting data, were published online January 12 in the Annals of Internal Medicine.

The 2009 guidelines evoked outrage from experts in the field and from some patient advocacy groups for their lukewarm (C recommendation) support for screening women in their 40s, and prompted a campaign to Stop the Guidelines.

But that campaign was based on a misunderstanding of the complex issues surrounding screening, Task Force members assert.

"Our 2009 recommendation has been incorrectly interpreted as a recommendation against screening for women in their 40s. Actually, the 2009 recommendation, and this updated scientific report, found evidence that supports a wide range of screening choices," said Kirsten Bibbins-Domingo, PhD, MD, vice chair of the USPSTF, in an audio interview furnished by the journal.

Undaunted by the controversy, the USPSTF members have stuck, albeit dispassionately, to their guns with the current guidelines, reiterating their previous statement that the ratio of potential benefits to possible harms most favors women from their 50s to mid-70s.

"Women who place a higher value on the potential benefit than the potential harms may choose to begin biennial screening between the ages of 40 and 49 years," USPSTF members write.

This is a C recommendation, meaning that the USPSTF recommends selectively offering or providing screening to individual patients on the basis of professional judgment and patient preferences. In contrast, the primary recommendation for biennial screening beginning at age 50 is a B recommendation, indicating that "there is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial."

Women in their 40s with a first-degree relative with breast cancer might also benefit more than similarly aged, average-risk women, the guidelines add (C recommendation).

The Task Force members also found that there is insufficient evidence to make recommendations about the benefits and risks of screening in women 75 years and older, the use of digital breast tomosynthesis as a primary screening method, and adjunctive screening with MRI or other techniques for women with dense breasts.

Table. Breast Cancer Screening Recommendations for Average-Risk Women

Guidelines Recommendation
USPSTF 2015  
   40–49 years Individualized decision-making based on a woman's values, preferences, and health history (C recommendation)
   50–74 years Mammography every 2 years (B recommendation)
   ≥75 years More research needed; indefinite evidence of benefit (I statement)
   40–44 years Women should have the choice to start annual breast cancer screening with mammograms
   45–54 years Mammography every year
   ≥55 years Mammography ever 2 years or annually according to personal preference; screening can continue if the woman is in good health and is expected to live at least 10 more years
   ≥40 years Annual clinical breast exam and annual mammography; upper age limit for screening not established; screening can continue if the woman is in good health and is expected to live at least 10 more years


Douse the Flames

The USPSTF is praised for doing "a difficult job well" by Christine Laine, MD, MPH, editor-in-chief of the Annals of Internal Medicine and senior vice president of the American College of Physicians, and her colleagues in an accompanying editorial.

And they call for a dousing of "the firestorm around breast cancer screening."

"Although for many years the dogma was that women should have mammograms 'once a year for a lifetime' starting at age 40 years, current evidence shows that the balance of risks and benefits of screening, particularly among women in their 40s, warrants more nuanced decision making," the editorialists write. "Potential harms of overdiagnosis and overtreatment of lesions with little progressive potential and harms of false-positive screening results with unnecessary biopsies and multiple repeated examinations must be considered," they add.

Metadata and Megamodels

When updating the guidelines, Task Force members were informed by data supplied by a systematic review and meta-analysis conducted for the USPSTF by Heidi D. Nelson, MD, MPH, from the Oregon Health Sciences University in Portland, and colleagues.

"Breast cancer mortality is generally reduced with mammography screening, although estimates are not statistically significant at all ages and the magnitudes of effect are small. Advanced cancer is reduced with screening for women aged 50 years or older," Dr Nelson and her colleagues report.

Evidence for the relative benefits and harms associated with different breast cancer screening strategies came from an independent source: the Cancer Intervention and Surveillance Modeling Network (CISNET). The CISNET investigators evaluated data from six models of various screening strategies, with various starting ages (40, 45, and 50 years) and various frequencies (annual, biennial, or a hybrid of annual for women in their 40s and biennial thereafter). The baseline comparator was no screening.

"Six models independently synthesized the most up-to-date information about breast cancer and breast cancer screening and treatment, and all came to the same conclusions about the balance of benefits and harms," Jeanne S. Mandelblatt, MD, MPH, from the Georgetown Lombardi Comprehensive Cancer Center in Washington, DC, who is a principal investigator with CISNET, told Medscape Medical News.

Her group found that strategies involving screening every 2 years were consistently the most efficient for women at average risk for breast cancer.

The models showed that for women 50 to 74 years, biennial screening would prevent a median of seven breast-cancer deaths, compared with no screening. If the screening started at age 40, three additional breast cancer deaths would be prevented, but there would be 1988 more false-positive results and seven more overdiagnoses for every 1000 women screened.

The CISNET investigators found that annual rather than biennial screening for women in the target age range of 50 to 74 years is "inefficient" because, although it is associated with benefits similar to other strategies, it is also associated with more harms.

Their analysis showed that "for groups with a two- to fourfold increased risk, annual screening from age 40 years had similar harms and benefits as screening average-risk women biennially from 50 to 74 years. For groups with moderate or severe comorbidity, screening could stop at age 66 to 68 years."

Dr Mandelblatt cautioned that their analysis was designed to serve as an aid in health-policy planning, not as an individual decision-making tool.

"Model results are intended to inform decisions at a population and public-health level; they are not intended to inform any individual decision making. Individual women need to discuss their preferences, their risk, and their density with their healthcare providers, and make a personalized shared decision based on the best evidence," she said.

Problem With Analysis of Harm

Despite the USPSTF recommendations, NCCN and M.D. Anderson Cancer Center screening guidelines will continue to recommend annual screening beginning at age 40 and continuing until a woman is within a decade of the predicted end of her life, according to Therese Bevers, MD, medical director of the Cancer Prevention Center at the M.D. Anderson Cancer Center in Houston, and chair of NCCN guideline panels on breast cancer screening and diagnosis and breast cancer risk reduction.

"At NCCN, we have a big problem with the harms analyses that have been done by both the Task Force and the ACS. That is, they talk about the harms of screening, but they don't talk about the harms of not screening, so in a sense, they are comparing the harms of screening with no harms, but that's clearly not the case," she said in an interview with Medscape Medical News.

For example, a woman who has never had a screening mammogram may have a palpable mass that on ultrasound will turn out to be a benign cyst, but the result will still be a false-positive, despite her lack of screening, Dr Bevers explained.

"So women will get a false-positive even without a screening mammogram and, more important, they're more likely to be diagnosed with a more advanced stage of breast cancer, more likely to have to undergo chemotherapy, more likely to have recurrence, and more likely to die. Those are harms. We're not comparing apples with apples, we're comparing apples with oranges," she said.

The USPSTF is supported by the US Agency for Healthcare Research and Quality. Dr Bibbins-Domingo, Dr Laine, Dr Nelson, Dr Mandelblatt, and Dr Bevers have disclosed no relevant financial relationships.

Ann Intern Med. Published online January 12, 2016. Full text, Editorial


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