The American Cancer Society continues to advise “women age 40 and older” to have a mammogram “every year and should continue to do so for as long as they are in good health.” Most privately operated medical institutions in the United States, reliant as they are on revenue streams from diagnostic and treatment procedures, echo the ACS’s guidance. [1]
Like the American Cancer Society, Memorial Sloan Kettering Cancer Center (for example) recommends annual screening mammography for asymptomatic women of “average-risk” beginning at age 40. The screening guidelines section on MSKCC’s website proclaims “studies have shown that regular screening of women with no symptoms has decreased the number of women who die from breast cancer approximately 45 percent.”[2] Those studies are not cited.
It is a sad testament to the reliability of medical guidelines emanating from the U.S. healthcare system that such institutions as the ACS and MSKCC continue to advocate annual screening mammography for asymptomatic women of average risk, even though the research fabric supporting the notion that screening mammography saves lives has thoroughly unraveled. The power of private sector medical revenue streams to influence such guidelines is suggested by the responses of various organizations to the United States Preventative Services Task Force breast cancer screening guidelines, reissued in 2009.
The USPSTF guidelines, based on the most comprehensive meta-analysis of screening data done to date, recommended mammograms for women aged 40-49 only if they are at risk for breast cancer [emphasis added], and every one to two years after age 50.[3] This revised schedule was widely criticized by medical organizations with a vested interest in the continuation of X-ray breast cancer screening.[4]
Most fierce in their resistance to the USPTF’s revised guidelines were American College of Radiology (ACR) and the Society of Breast Imaging, both medical trade associations: “These unfounded USPTF recommendations,” alleged the ACR, “ignore the valid scientific data and place a great many women at risk of dying unnecessarily from a disease that we have made significant headway against over the past 20 years.”[5]
The Society of Breast Imaging (SBI) was less temperate, calling the USTPF recommendations “a step backward . . . shocking” and “a significant harm to women’s health.” Like the ACR, the society defended regular mammograms for women beginning at 40 years as an “approach [that] has overwhelmingly been shown to save lives.”[6]
The National Cancer Institute, however, whose “primary role as a biomedical research agency is to generate scientific knowledge that can be used by the Task Force and other organizations in their deliberations and recommendations,” did not agree. “Today’s report reflects the fact that more questions need to be answered.” Neither did eleven other health care and cancer prevention organizations, who wrote the leadership of the U.S. House committee responsible for government oversight and public health:
The US Preventive Services Task Force was established as an independent body to apply rigor and objectivity to the analysis of clinical preventive care—even on issues that arouse passions and political posturing. The misstatements we have noted are evidence of both of these dangers, and the Task Force is our best defense against both.[7]
What the disputed 50 year threshold for routine mammography for all women further revealed was that a compelling scientific case had not been made that mammography’s “risks outweigh its benefits” on either side of that age. And, since most everyone who has lived longer than 50 years has noticed that biological and calendar age are not one and the same, the entire proposition of basing mammography screening on calendar age is problematic at the least.
The controversy continued when the British Medical Journal published, on February 11, 2014, a summary of the results of a twenty five year follow-up for breast cancer incidence and mortality by the Canadian National Breast Screening Study. The article reported that the Canadian study, begun in 1980, after 25 years-
. . . found no reduction in breast cancer mortality from mammography screening in a programme offering five annual screens, neither in women aged 40-49 at study entry nor in women aged 50-59. Although the difference in survival after a diagnosis of breast cancer was significant between those cancers diagnosed by mammography alone and those diagnosed by physical examination screening, this is due to lead time, length time bias, and overdiagnosis.[8]
Memorial Sloan Kettering’s deputy physician-in-chief for breast cancer programs was quick to denounce the Canadian study, claiming it was so “flawed” that “it should not influence any changes in screening recommendations.”[9]
If the Canadian study’s limitations–imperfect randomization, uneven skills among imaging technologists, and variable quality mammograms—invalidated its conclusions, then so also did those same flaws invalidate the HIP-GNY and BCDDP conclusions (see preceding posts).[10] In any event, the BMJ article contains extensive discussion of these aspects of the Canadian study, concluding that “the lack of an impact of mammography screening on mortality from breast cancer in this study cannot be explained by design issues, lack of statistical power, or poor quality mammography.”[11]
Close on the heels of the British Medical Journal’s 2014 report of the Canadian study came “Abolishing Mammography Screening Programs? A View from the Swiss Medical Board,” published in the May 22, 2014 issue of the New England Journal of Medicine.[12] If the Canadian study reported a few months earlier nudged at the conceptual boundaries of previous quantitative studies of mammography’s benefits, the Swiss group created a new outward salient. No doubt this was partly a result of the wider disciplinary reach of the study group’s members, who included, in addition to physicians, a medical ethicist, a clinical epidemiologist, a nurse scientist, a lawyer, and a health economist.
The debate over mammography consists largely of “reanalyses of the same, predominantly outdated trials,” argued the Swiss group. More importantly, the extent of over diagnosis (previously detected by the Nordic Cochrane Center’s analyses) reported in the Canadian study meant that over 100 women “were diagnosed with and treated for breast cancer unnecessarily, which resulted in needless surgical interventions, radiotherapy, chemotherapy, or some combination of these therapies.” Here the Swiss group was amplifying the female patient-centered warnings of a growing minority of American physicians that annual mammography screening was subjecting numerous healthy women to unnecessary expense, emotional turmoil, invasive procedures, toxic treatments and risks from disfiguring surgery.[13]
The Swiss board further extended its recognition of those who had the most at stake in this controversy—women—by incorporating the findings of a four-country population based survey of women’s perception of the benefits of mammography screening. That survey revealed that “in the US and three European countries a high proportion of women overestimated the benefits that can be expected from screening mammography.”
Whereas the women sampled believed that, without mammography screening, 20% of women would die of breast cancer within 10 years, the actual percentage was one-half of one percent, or .5%, who would die of breast cancer in that period. “This finding,” concluded the survey, “raises doubts on informed consent procedures within breast cancer screening programmes [sic].” [14]
Still, that finding could also provide gratifying assurances to the American Cancer Society that its 30-year campaign to promote X-ray breast cancer screening among asymptomatic women had been a success. That success could be confirmed by other numbers: The proportion of women 40 years and older having mammographies within a 2 year period increased from less than 30% in 1987 to nearly 70% by 2000. (Among women 50-64 years the increase nearly reached 80 %.)[15]
(Published June 17, 2015. The next post looks at the National Cancer Institute’s review of the most recent research into the harms and benefits of screening mammography and the resulting update of its own guidelines.)
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[1] Austin Frakt and Aaron E. Carroll, “If Patients Only Knew How Often Treatments Could Harm Them,” The New York Times (March 2, 2015).
[2] Memorial Sloan Kettering Cancer Center (MSK) in New York, founded in 1884, was one of the sites for the Breast Cancer Detection Demonstration Project and in 1996 it acquired the Guttman Institute founded in 1968 by Dr. Philip Strax, head of the Health Insurance Plan of Greater New York’s highly touted study of breast cancer screening. Memorial Sloan Kettering Cancer Center, “Screening Guidelines” http://www.makcc.org/cancer-care/adult/breast/screening-guidelines. Downloaded March 2, 2015.
[3]http://www.uspreventiveservicestaskforce.org/Page/Topic/recommendation-summary/breast-cancer-screening. Downloaded October 13, 2014. The U.S. Preventive Services Task Force, created in 1984 by the federal Agency for Healthcare Research and Quality, is an independent, volunteer panel of national experts in prevention and evidence-based medicine. The guidelines included a recommendation that women not be taught breast self-exam, arguing that BSE was more likely to lead to “anxiety, unnecessary visits, imaging, and biopsies.” In December, 2009, the USPTF updated its guidelines to read: “The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient’s values regarding specific benefits and harms.” US Preventive Services Task Force, “Screening for Breast Cancer,” Updated December 2009. http://www.uspreventiveservicestaskforce.org/usptf/uspsbrca.htm (Downloaded September 9, 2014).
[4] NBC Nightly News, November 17, 2009. http://www.nbcnews.com/video/nightly-news/34002015#34002015
[5] Quoted in “Major Cancer Agencies Respond to USPTF’s New Mammography Guidelines,” Oncology Journal (December 15, 2009).
[6] Quoted in “Major Cancer Agencies Respond to USPTF’s New Mammography Guidelines,” Oncology Journal (December 15, 2009)
[7] Quoted in “Major Cancer Agencies Respond to USPTF’s New Mammography Guidelines,” Oncology Journal (December 15, 2009). The organizations were the American Academy of Family Physicians, American Academy of Nurse Practitioners, American Academy of Physician Assistants, American College of Physicians, American College of Preventive Medicine, American Journal of Preventive Medicine, American Public Health Association, National Association of County and City Health Officials, Partnership for Prevention, and the Trust for America’s Health.
[8] Anthony B.Miller, Claus Wall, Cornelia J. Baines, Ping Sun, Teresa To, and Steven A. Narod, “Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial,” British Medical Journal (11 February 2014), http://www.bmj.com/content/348/bmj.g366, Downloaded March 2, 2015.
[9] Memorial Sloan Kettering Cancer Center, “In the News: Recent Study Should Not Change Mammography Guidelines” (February 12, 2014), http://www.mskcc.org/blog/recent-study-should-not-change-mammography-guidelines. Downloaded March 2, 2015.
[10] Daniel B.Kopans and Stephen A. Feig, “The Canadian National Brfeast Screenoing Study: A Critical Review,” American Journal of Roentgenology, Vol. 161 (October, 1993).
[11] Anthony B.Miller, Claus Wall, Cornelia J. Baines, Ping Sun, Teresa To, and Steven A. Narod, “Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial,” British Medical Journal (11 February 2014), http://www.bmj.com/content/348/bmj.g366, Downloaded March 2, 2015.
[12] Nikola Biller-Adorno, M.D., Ph.D. and Peter Jűni, M.D., “Abolishing Mammography Screening Programs? A View from the Swiss Medical Board,” The New England Journal of Medicine (May 22, 2014), pp. 1965- 1967. Original report published February 2, 2014 on Swiss Medical Board website: http://www.medical-board.ch/fileadmin/docs/public/mb/Fachberichte/2013-12-15_Bericht_Mammographie_Final_rev.pdf (Downloaded October 6, 2014).
[13] See, for example, Archie Bleyer, M.D., and H. Gilbert Welch, M.D., M. P. H., “Effect of Three Decades of Screening Mammography on Breast Cancer Incidence,” The New England Journal of Medicine (November 22, 2012), pp. 1998-2005.
[14] Domenighetti G., D’Avanzo B., Egger M., et al. “Women’s Perceptions of the Benefits of Mammography Screening: Population Based Survey in Four Countries.” International Journal of Epidemiology, Vol. 32 (2003), pp. 816-821. Over 4,000 randomly sampled women in the United States, Italy, the United Kingdom, and Switzerland were surveyed.
[15] Source: Centers for Disease Control and Prevention, National Center for Health Statistics, http://www.cdc.gov/nchs/faststats/mamogram.htm, downloaded March 23, 2014.
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