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Date of release: 15 November, 2010

Guidelines for screening mammography


In 2009, the US Preventive Services Task Force (USPSTF) revised its guidelines concerning analog screening mammography [1]. Recently, Laurie Margolies has written a comprehensive critique of the USPSTF recommendation [2]. Despite the breast cancer death rate falling by 30% since 1990 and mammography receiving the major share of the credit for the decrease, the USPSTF no longer advises routine screening mammography for women between the ages of 40 and 49 years. It does advise biennial screening for those aged 50–74 years but does not make a recommendation regarding screening for those aged ≥ 75 years. The recommendations do not cover digital mammography. Primary-care providers need to understand the data so they can assist patients making decisions about breast cancer screening.

Comment

In November 2009, the USPSTF published its revisions [1] to its 2002 breast cancer screening guidelines. The USPSTF no longer recommends screening mammography for women under the age of 50 years and has increased the screening interval to 2 years, such that it recommends biennial mammography from the age of 50 to 74 years. These recommendations disagree with the recommendations of the American Cancer Society: ‘"Y"early mammograms are recommended starting at age 40 and continuing for as long as a woman is in good health’ [3]. The most important effect of such guidelines is the confusion created among women and their primary-care physicians: in practical terms, who is one to trust?
 
Guidelines and protocols dominate medical practice in order to effectively deliver all aspects of health care to the widest possible section of the target population. The underlying principle helps to limit unnecessary spending and, until recently, attracted the confidence of the profession and the public. Screening mammography is one of the most effective clinical procedures in the practice of medicine but it is not cheap. Data from Europe and from the United States show that mammography commenced in women from the age of 40 saves lives and significantly reduces the incidence of interval cancers. A number of factors operate in the conclusion of the USPSTF report; some are legitimate but unfortunately lacking were greater openness, the utilization of data from peer-accepted clinical trials, and the genuine engagement of the profession and the public.  
 
It is generally recognized that the quality of medical care in a society is an index of its prosperity. Prosperity in the western world over the last 60 years has steadily raised the benchmark for health and, naturally, nurtured heightened expectations from the population we serve. The aspirations of the client population have changed. They are focused on physical fitness and internet technology and a wish for lifelong possibilities that include illimitable cosmetic, prosthetic, virtual and informational worlds. This enrichment of modern life is always threatened by morbidities and ‘untimely’ mortality, making today’s client group supportive of any measure that overcomes these threats. This social progress prompted the deployment of scientific endeavours into clinical medicine and many screening tests have met with a warm reception.  
 
A screening program is deemed appropriate when it is affordable, designed to detect a serious disease, its sensitivity and specificity are high, and the process is conducted with minimal invasiveness and inconvenience to the person. Where the public purse funds a given screening program, two caveats become fundamental: first, the achievement of the most health effect per unit currency spent, and, second, the whole target population must have equal access. Co-pay (a type of insurance policy where the insured person is expected to pay a specified amount for a doctor visit or prescription drugs at the time the service is rendered) is regarded as immoral as it enables certain sections of the society to advantageously utilize these programs. In questioning the morality of co-pay, we need to consider the potential for co-pay to top up public funds, which in turn may enable effective reach to be made to those who are at higher risks and cannot pay. Co-pay also enables the all-important future research and development (R&D). However, the socialist structures of health care can frequently be oblivious to the concept of R&D.  
 
Does the screening test cause anxiety? Every test for a serious disease may cause anxiety, but, for the individual who develops the disease when screening was not conducted, it causes equal, if not more, anxiety, resentment and regret. The dose of radiation and high benign biopsy rates are cited as added potential harms. Although not addressed by the Task Force, the impact of interval cancers on the patient, her family and on resources required for care in advanced cancer constitute equally profound harms. Then, why has the Task Force elected to ignore the 24–44% reduction in breast cancer mortality reported in the Swedish data, which were independently generated when mammography was commenced at the age of 40, and adopted a figure of 15% instead? The 15% reduction was derived from an unblinded and discredited Canadian study [4]. The basis of the report relied on seven outdated clinical trials out of eight and the eighth recent study was not regarded of sufficiently high quality; these facts make one question the wisdom that underpinned such a report. Included in the data analyzed was information derived from single-view mammograms and, as such, this dampened the impact of two-view mammography on early detection. Neither did the Task Force consider digital mammography techniques. The membership of the Task Force locked itself into analyzing randomized, controlled trials that cannot ethically be repeated and simply did not consider a plethora of observational studies that were just as important. Two questions arise:
 
1. Are the guidelines evidence-‘based’ medicine advising on how best to protect the population? Or is the evidence-‘biased’ committee work trying to justify the health economists’ views on re-direction of resources under the guise of mathematical models? 
2. How could one contrast the morality of the non-worthiness of saving 19% of breast cancer deaths against the ‘immorality’ of co-pay?
 
Assuming that 30,000 breast cancers are diagnosed each year in women aged 40–49 years (near enough to the actual incidence in the USA), there will be 5400 deaths within 5 years. To translate the potential for screening mammography in reducing mortality by considering the figures of 15% and 44% from the USPSTF and the Gothenburg Breast Cancer Screening Trial [5], respectively, there will be 810–2376 lives saved. The true figure is somewhere in between, however. It would be informative to know the value of life in the eyes of the USPSTF and in the eyes of the funding public.  
 
The USPSTF will never be able to convince women that breast cancer is not relevant to their lives nor would it be able to persuade them that saving one-fifth of cancer deaths is not an appropriate disposal of resources. Understanding guidelines by not recommending mammography does not mean absence of disease. Women are clever and, with the easy access to the internet, they obtain knowledge and prepare the means to obtain the test that satisfies them. The USPSTF should have presented the balance sheet to the profession and members of the public and stated that the public purse could no longer spend money on this area of health care, rather than present an inaccurate report. The USPSTF report would have had much more credence had it concluded that informed women at any age who could afford to buy the service should not be persuaded against screening mammography.

Comentario

Farook Al-Azzawi
Gynaecology Research Unit, University Hospitals of Leicester, Leicester, UK

    References

  1. US Preventive Services Task Force. Screening for breast cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med 2009;151:716-26.
    http://www.ncbi.nlm.nih.gov/pubmed/19920272

  2. Margolies L. Mammographic screening for breast cancer: 2010. Mount Sinai J Med 2010;77:398-404.
    http://www.ncbi.nlm.nih.gov/pubmed/20687187

  3. American Cancer Society. Guidelines for the early detection of cancer.
    http://www.cancer.org/Healthy/FindCancerEarly/CancerScreeningGuidelines/american-cancer-society-guid

  4. Miller A, To T, Baines C, Wall C. The Canadian National Breast Screening Study. 1. Breast cancer mortality after 11 to 16 years of follow-up. A randomized screening trial of mammography in women age 40 to 49 years. Ann Intern Med 2002;137:305-12.
    http://www.ncbi.nlm.nih.gov/pubmed/12204013

  5. Bjurstam N, Bjorneld L, Warwick J, et al. The Gothenburg Breast Screening Trial. Cancer 2003;97:2387-96.
    http://www.ncbi.nlm.nih.gov/pubmed/12733136