June 28th, 2012 by Hasham
Sorting Through The Recent Controversies in Breast Cancer Screening
Taussig Cancer Institute, Cleveland Clinic; Member, Cleveland Clinic Breast Cancer Screening Task Force
ANDREA SIKON, MD
Department of Internal Medicine, Center for Specialized Women’s Health, Cleveland Clinic; Member, Cleveland Clinic Breast Cancer Screening Task Force
ALICE RIM, MD
Vice Chair, Imaging Institute; Section Head, Breast Imaging, Department of Diagnostic Radiology, Cleveland Clinic; Member, Cleveland Clinic Breast Cancer Screening Task Force
MELANIE CHELLMAN-JEFFERS, MD
Section of Breast Imaging, Department of Diagnostic Radiology, Imaging Institute, Cleveland Clinic; Member, Cleveland Clinic Breast Cancer Screening Task Force
JOSEPH CROWE, MD
Chairman, Breast Services, Department of General Surgery, Taussig Cancer Institute, Cleveland Clinic; Member, Cleveland Clinic Breast Cancer Screening Task Force
In november 2009, the US Preventive Services Task Force (USPSTF) announced its new guidelines for breast cancer screening—and created an instant controversy by suggesting that fewer screening tests be done.1
The November 2009 update recommended that most women wait until age 50 to get their first screening mammogram instead of getting it at age 40, that they get a mammogram every other year instead of every year, and that physicians not teach their patients breast self-examination anymore. However, on December 4, 2009, the USPSTF members voted to modify the recommendation for women under age 50, stating that the decision to start screening mammography every 2 years should be individualized, taking into account the patient’s preferences after being apprised of the possible benefits and harms.2
Various professional and advocacy groups have reacted differently to the new guidelines, and as a result, women are unsure about the optimal screening for breast cancer.
The USPSTF commissioned two studies, which it used to formulate the new recommendations.3,4 Its goal was to evaluate the current evidence for the efficacy of several screening tests and schedules in reducing breast cancer mortality rates.
An updated systematic review
Nelson et al3 performed a systematic review of studies of the benefit and harm of screening with mammography, clinical breast examination, and breast self-examination.
Screening mammography continued to demonstrate a reduction in deaths due to breast cancer. The risk reduction ranged from 14% to 32% in women age 50 to 69. Similarly, it was calculated to reduce the incidence of deaths due to breast cancer by 15% in women age 39 to 49. However, this younger age group has a relatively low incidence of breast cancer, and therefore, according to this analysis, 556 women need to undergo one round of screening to detect one case of invasive breast cancer, and 1,904 women need to be offered screening (over several rounds, which varied by trial) to prevent one breast cancer death.3
Most of the harm of screening in the 39-to-49-year age category was due to false-positive results, which were more common in this group than in older women. The authors calculated that after every round of screening mammography, about 84 of every 1,000 women in the younger age category need additional imaging and about 9 need a biopsy. The issue of overdiagnosis (detection of cancers that would have never been a problem in one’s lifetime) was not specifically addressed for this age category, and in different studies, estimates of overdiagnosis rates for all age groups varied widely, from less than 1% to 30%.
Beyond age 70, the authors reported the data insufficient for evaluating the benefit and harm of screening mammography.
Canada Breast Cancer Screening Guidelines Ignite Controversy
The release this week of revamped Canadian breast cancer screening guidelines has set off a war of words between those who support the recommendations and those who predict that following them will lead to more women dying of the disease.
Caught among all the rhetoric are women themselves. And what are they to think — and more importantly, to do?
The most vociferous criticism of the guidelines developed by the Canadian Task Force on Preventive Health Care is focused on its direction to average-risk women in their 40s. The expert panel advises against routine mammography in this age group, saying that potential harms arising from the test trump the possible benefit of a small reduction in deaths.
Those harms include false-positive results requiring repeat tests, biopsies and in some worst-case scenarios, unnecessary mastectomies, radiation and chemotherapy. A review of international clinical trial evidence, on which the guidelines are based, shows a third of women will have a false-positive.
The task force determined that 2,100 women would have to be screened every two to three years over an 11-year period to prevent one breast cancer death.
“What I take away from the number is if you are a woman 40 to 49, if you and 999 other women go for screening, no one in the group will see a life saved,” said task force chair Dr. Marcello Tonelli of the University of Alberta. “You need to have a group of 2,100 before you’d save a life.
“And looking around the room, one in three of you would have a false positive result … and one in 30 of you would have a biopsy that you didn’t need. And some of you would have an unnecessary mastectomy, or breast removed, or chemotherapy.”
But Dr. Nancy Wadden, chair of the mammography accreditation program for the Canadian Association of Radiologists, contends the guidelines are based on studies from 25 to 40 years ago, using outmoded mammography that is rarely used today.
“We’ve come so far with improvements in breast imaging since that time, for example digital mammography, but even the (X-ray) film-screen mammography is totally different,” Wadden, a radiologist who is medical director of the breast screening program for Newfoundland and Labrador, said from St. John’s.
She estimates that up to 80 per cent of breast screening centres in Canada employ digital mammography, which allows radiologists to assess high-resolution breast images on a computer screen. As well, radiologists are now better trained “to recognize cancers at an earlier stage than when those trials were conducted,” said Wadden.
“So the conclusion from those trials is not relevant to the way that breast imaging occurs in 2011.”
Tonelli said the task force didn’t pick and choose, but looked at all high-quality randomized control trials that compared screening and not screening, “and we don’t find any evidence that more recent studies reached different conclusions about the benefits of mammography.”
“There is no question that digital mammography is more sensitive, meaning that it picks up smaller abnormalities than film mammography,” he said. “But there is no evidence that digital mammography improves outcomes to a greater extent than film mammography.
“In fact, there is reason to think that digital mammography may be associated with a higher risk of false-positives than the older technology.”
But the Canadian Association of Radiologists contends more women will die of breast cancer if the guidelines — which also stretch the interval between mammograms to two to three years for women 50 to 74 — are followed.
“I certainly hope not, but I am concerned that women will not get their mammogram in a timely fashion,” said Wadden, adding that so-called interval tumours can arise and grow unchecked between mammograms. “And we do know that the earlier you find a cancer, the better the prognosis. This is not unique to breast cancers, this is with all types of cancers.”
This year in Canada, an estimated 23,600 women overall will be diagnosed with breast cancer and about 5,100 will die of the disease. Among them will be about 390 women age 40 to 49, including those with a high risk of breast cancer due to family history or a genetic mutation. Some of their cancers may be caught by mammograms, others not.
The Canadian Breast Cancer Foundation, an advocacy and research funding organization that challenges the recommendations, suggested this week that routine screening could cut deaths among women in their 40s by 25 to 39 per cent.
Tonelli called such figures “purely speculation. In my opinion, they are overestimates of overestimates.
“I think we need to be really careful that we don’t start scaring women into a default choice. The whole purpose of our guidelines is to try to allow women to make an informed decision, and in my opinion introducing this element of fear is counterproductive.”
In fact, research shows that worldwide, the rates of death from breast cancer have actually been declining — even among populations without routine screening programs.
While mammography studies in the 1960s to the early ’80s showed mammography translated into lower death rates, the subsequent use of the preventive drug tamoxifen and the addition of post-surgical chemotherapy for women diagnosed with breast cancer appears to have changed the picture, said epidemiologist Dr. Cornelia Baines of the University of Toronto.
In the ’70s and ’80s, screening mammography did reduce mortality, Baines agreed. “But in 2011, therapy is achieving so much, there’s not much room for screening to have any impact.”
And the programs are extremely costly, she said. In Canada, estimates are pegged as high as $500 million a year.
Controversy Persists Over Breast Cancer Screening Guidelines
Preventive Services Task Force released updated breast cancer screening guidelines, some physicians and lawmakers continue to call for the guidelines’ withdrawal, Long Island Newsday reports.
The guidelines recommend that women with a normal risk for breast cancer begin breast cancer screening and mammograms at age 50, rather than age 40. USPSTF said the change was meant to reduce harm from overtreatment and patient anxiety. The task force also recommended against teaching breast self-examination and said women ages 50 through 74 should undergo less-frequent mammograms.
According to Newsday, HHS Secretary Kathleen Sebelius issued a statement one day after the guidelines were issued, saying that they did not represent government policy and that women should continue to “do what [they]‘ve always done.” The guidelines, which are posted on a website run by HHS, have been modified to state that women ages 40 through 49 who want mammograms should get them if their doctor advises it.
Nonetheless, the controversy surrounding the guidelines “will not go away,” Newsday reports. In May, Sen. David Vitter (R-La.) claimed in a letter to Sebelius that the federal health reform law (PL 111-148) required the government to retract the guidelines. He wrote, “The fact that these recommendations are still being presented to the general public as ‘current’ is only serving to further confuse women on this critical issue.” He added that the guidelines “were ill-conceived from the start” and “represent a step backward in our fight against a horrible disease.” Vitter requested that HHS remove the guidelines from the Internet and “cease all promotion” of them.
Joe DiGrado, Vitter’s spokesperson, said the senator has not yet received a response from Sebelius. HHS did not respond to questions from Newsday regarding whether the department is considering withdrawing the guidelines (Ricks, Newsday, 7/12).