One of the main talking points at the recent annual meeting of the RSNA held in Chicago at the beginning of December was the recent publication from the U.S. Preventive Services Task Force (USPSTF) of revised screening mammography guidelines, proposing that mammography screening should be carried out less often and starting at a later age. At one level, this is an affair that seems to affect only the United States since, in Europe, the situation regarding recommendations on mammography screening is much more disparate than in America. In Europe, different countries have different guidelines, recommendations and re-imbursement policies. However, the fact is that any conclusions drawn about the pros and cons of mammography screening based on the vast US database have direct relevance to Europe. We report here on the background to the controversy and on the reaction of a select RSNA panel of experts in mammography who did not hide their negative response to the proposed new guidelines.

The clinical background
Breast cancer is the most frequently diagnosed noncutaneous cancer and the second leading cause of cancer deaths among women. The incidence increases with age and the probability of a woman developing breast cancer is 1 in 69 in her 40s, 1 in 38 in her 50s, and 1 in 27 in her 60s [1]. Data suggest that the incidence of breast cancer in the US and in the developed world has stabilised in recent years and mortality has decreased since 1990 thanks to many factors, including screening [2]. In 2005, 68% of women aged 40 to 65 years had screening mammography within the previous 2 years in the United States.
Breast cancer is known to have an asymptomatic phase that can be detected with mammography. Mammography screening is sensitive (77% to 95%), specific (94% to 97%), and acceptable to most women. It is carried out by using either plain film or digital technologies, although the shift to digital is increasing. Contrast-enhanced magnetic resonance imaging (MRI) has traditionally been used to evaluate women who have already received a diagnosis of breast cancer. Recommendations for its use in screening apply to certain high-risk groups only. If a woman has an abnormal mammographic finding on screening or a concerning finding on physical examination, additional imaging and biopsy may be recommended. Such additional imaging may consist of diagnostic mammography or mammography done with additional or special views, targeted breast ultrasonography, or breast MRI. Additional imaging may help classify the lesion as a benign or suspicious finding to determine the need for
biopsy. Biopsy techniques vary in the level of invasiveness and amount of tissue acquired, which affects yield and patient experience.

The USPSTF
The United States Preventive Services Task Force (USPSTF) is a panel of outside experts that is charged with making evidence-based recommendations to both the public and the health care community regarding the provision of clinical preventive services. The mission of the USPSTF is to produce evidence-based recommendations on the appropriate screening, counselling and provision of preventive medication for asymptomatic patients who are seen in the primary care setting. There are currently 16 members on the USPSTF, with expertise in the fields of primary care, epidemiology, health policy and public health. The necessary qualifications for serving on the USPSTF are a knowledge and experience in the critical evaluation of research published in peer-reviewed literature and in the methods of evidence review. The members should be expert in disease prevention and health promotion and have clinical expertise in the primary health care of children or adults. Crucially, there is no breast cancer screening expert currently serving on the USPSTF.
The current USPSTF recommendations for mammography screening are shown in Table 1. The new, recently published guidelines [1] are shown in Table 2.

Radiologists respond.
A panel of radiologists, expert in mammography got together at the recent RSNA meeting to refute the new guidelines. The panel comprised:
• Dr Phil Evans, Director, Center for Breast Care, University of Texas Southwestern Medical Center and President, Society of Breast Imaging
• Dr Stephen A. Feig, Professor of Radiology, University of California Irvine School of Medicine and President-Elect, American Society of Breast Disease
• Dr Daniel B. Kopans, Senior Radiologist, Breast Imaging Division, Massachusetts General Hospital and Professor of Radiology, Harvard Medical School.

The principal point that the panel made was that the new guidelines were not based on scientific evidence. Most importantly, according to many experts, the guidelines would actually cause unnecessary deaths. In fact the panel presented screening mammography as being one of the great women’s health success stories of the last couple of decades. The reduction in mortality from breast cancer in women who were screened annually is actually between 40 and 50% so that today the average patient with invasive cancer is 39% less likely to die from her disease than in the early 1980s. Perhaps reflecting this, the number of women aged 40 and older who actually followed the old recommendation on mammography screening has risen from 29% in 1987 to 70% in 2003. Several randomised trials, including European studies [3,4] were presented as proof of the benefits of initiating screening in women between the age of 40 and 50 [Table 3].
Turning to the points raised by the USPSTF regarding the potential radiation risk caused by mammography screening, the panel of mammography experts quoted recent studies by the US National Council on Radiation Protection and Measurements which showed that at current mammography radiation doses, even a 1% reduction in mortality confers more benefit than the risk of the screening procedure itself [5]. Since the actual mortality reduction is of the order of 40 % the benefits far outweigh the theoretical radiation risk. As for the psychological stress caused to the patient as a result of the level of false positives which required a recall for further investigation or in extreme cases, even a biopsy, the panel admitted that screening mammography was not perfect but pointed out that the real stress occurred with women who had not had screening and who unfortunately realised that they had potentially lethal breast cancer.

References
1. Nelson, HD et al Screening for breast cancer: an update for the US preventive task force. Ann Intern Med. 2009 ;Nov 17;151(10):727-37, W237-42.
2. Edwards BK et al Annual report to the nation on the status of cancer, featuring population-based trends in cancer treatment. J Natl Cancer Inst. 2005; 97:1407.
3. Bjurstam N et al. The Gothenburg breast screening trial: first results on mortality, incidence, and mode of detection for women ages 39-49 years at randomization. Cancer 1997 Dec 1;80(11):2091-9.
4. Andersson, I & Janzon L. Reduced breast cancer mortality in women under age 50: updated results from the Malmö Mammographic Screening Program.
J Natl Cancer Inst Monogr 1997;(22):63-7.
5. National Council on Radiation Protection and Measurements “A guide to mammography and other breast imaging procedures” NRCP report no 149, 2004