Breast Cancer Screening Recs: A Review of Recent Articles and Position Statements

The United States Preventative Services Task Force (USPSTF) released changes regarding the recommendations for screening mammography on November 16th, 2009. Previous recommendations stated that screening mammography should be performed every one to two years for women beginning at age 40.

The 2009 recommendations changed this to routine screening bi-annually beginning at age 50 and stopping at the age of 74. For women aged 40-49 the recommendation is that the decision to screen is an individualized one, and overall, this population should not be screened routinely.¹ The USPSTF felt that there is insufficient evidence to assess the harms and benefits for women 75 years of age and older. Clinical breast exam was found to be insufficient in regards to additional benefit and the USPSTF felt that breast self-examination (BSE) does not reduce breast cancer deaths and should not be done.

The American Cancer Society (ACS) continues to recommend annual screening beginning at age 40. ACS does not have specific recommendations in regards to when to cease screening, but rather states the decision should be made on an individual basis, weighing the risks and benefits.² The conflicting recommendations have led to a great amount of confusion within society, amongst both patients and physicians, unfortunately leading some patients to stop screening altogether.

As part of their process of determining the new recommendations, the USPSTF examined randomized controlled trial (RCT) data compiled in a report by the Oregon Evidence-Based Practice Center, as well as a more detailed report, both funded by the Agency for Healthcare Research and Quality, on screening mammography. The USPSTF evaluated the “harms” of screening mammography, which included considering factors such as radiation exposure, pain during procedures, patient anxiety/psychological responses, consequences of false-positive and false-negative test results, and over-diagnosis of breast cancer. The USPSTF also reviewed modeling of various screening mammography regimens.

The new recommendations surprised the breast imaging community, as for years it has been functioning with the knowledge of decreased breast cancer mortality as a direct result of yearly screening mammography. Experts in the field of medicine have spoken out, both in support for and in opposition to, the new recommendations.

Opposition to Task Force Recommendations

Some have argued that the USPSTF review was flawed, as it did not include evaluation of several pieces of evidence that would be vital to the final recommendations. Hendrick and Helvie³ wrote an article examining the scientific evidence considered by the USPSTF and list several aspects not included in the formulation of the new recommendations. These include all peer-reviewed studies assessing the benefit of screening mammography that were not in randomized controlled trials using mortality as the outcome measure, including all service screening results, such as the Swedish screening trial and the British Columbian study results. All peer-reviewed analyses of the cost-benefit of screening mammography compared with other interventions were excluded as well.

The authors state that the USPSTF chose to ignore the science available to them and overemphasized potential harms of screening. Hendrick and Helvie used six models, concluding that annual screening mammography from age 40 to 84 would result in an estimated 39.6 percent reduction in mortality in comparison to the USPSTF guidelines of biennial screening of women aged 50 to 74 years resulting in an estimated 23.2 percent reduction in mortality, a 71 percent higher mean mortality reduction from annual screening mammography than from biennial screening. Their discussion focused on USPSTF’s results, in which the authors point out that the Task Force failed to delineate the importance of mortality reduction and life years gained when comparing the ACS’s guidelines to the USPSTF’s. The Task Force also failed to discuss the “harms” of not screening, while discussing the “harms” of misdiagnosis and false positives.

In January of 2010, the Journal of the American Medical Association (JAMA) published several commentaries regarding the Task Force recommendations. DeAngelis and Fontanarosa⁴ wrote one such commentary in which they discuss the role and mission of the task force as well as the importance of physicians and patients relying on unbiased available evidence regarding breast cancer screening.

There have been many published studies reporting on screening mammography, yet the USPSTF did not include these in the decision-making process if they were not RCTs. As shown by two observational studies of both the screened and unscreened populations, there was a reported reduction of 30 percent to 40 percent in breast cancer mortality for women in their 40s.⁵ This information was not included in the USPSTF’s review.

Dr. Berg⁵ discussed how the RCT’s used by the task force underestimated the true benefits of screening, stressing that an assumed 30 percent reduction in breast cancer deaths prevents more than 2,000 deaths per year in the Unites States for women in their 40s. Dr. Berg also points out a very important fact that the task force did not consider: 75 percent of newly diagnosed breast cancers of women in their 40s were in women with no associated risk factors and that cancers found in this younger population tend to be more aggressive. She re-enforced that mammography is the only test to date that reduces mortality due to breast cancer, and that screening is appropriate starting at 40 and should continue as long as a patient is in good health.

A long-term study, well known in the breast imaging community, conducted by Tabar and colleagues⁶ began to evaluate mammography screening in the early 1980s in two counties in Sweden. From the onset of the study, it has reflected the benefits screening mammography provides to women. To date Tabar’s study is one of the most extensive and longest-running studies looking at the benefits of screening mammography.

As recently as June 2011, 29 years after the start of the study, additional results were released,⁷ continuing to provide evidence of the long-term benefits of regular mammography screening. The study, which has included 130,000 women, has shown that 30 percent fewer women in the group obtaining screening died of breast cancer and this effect continued to persist over the years. This study initially began with utilizing single view mammography with interval screening at 23 to 33 months, with the belief that had they utilized the two-view mammogram and screened at 12-month intervals, the impact on screening would have been even greater.

In a 2009 ACR Chair’s Memo⁸ (published in the Journal of the American College of Radiology), Dr. James Thrall passionately discusses the flaws in which the Task Force gathered data, using science with some recommendations and theory with other recommendations. He points out that the recommendations were “startling for the lack of evidence to support them,” especially when addressing the harms of unnecessary treatment and radiation exposure, when there is no existing data on “whether women are willing to trade years of their lives for the supposed reduced anxiety of not going through the screening process with its inevitable false-positives and risks of over treatment.” Another observation he made was the fact that none of the Task Force members had expertise in imaging or breast cancer screening, stating on one hand that there is the need for non-bias within the statistical evaluation. However it is questionable how the same group was able to voice their subjective view regarding anxiety negating the benefits of screening without any expertise or first-hand experience on the matter. Dr. Thrall questioned why the Task Force favored modeling as opposed to direct data from other countries regarding decreased mortality and went on to state that their main goal should have been to get the numbers correct rather than basing the recommendations on theoretical models.

He further discussed that the number of screening mammography imaging centers in the United States has decreased due to dropping reimbursement rates, high malpractice fees, and lack of health insurance, which directly reflects that only 25 percent of Americans follow screening recommendations resulting in a diminished life expectancy when compared to other first-world countries.

In January of 2010, the Society of Breast Imaging (SBI) and the Breast Imaging Commission of the ACR issued their recommendations/guidance to patients and clinicians on imaging for screening of breast cancer.² These recommendations are mostly evidence based and where evidence was lacking, a consensus opinion recommendation of the SBI fellows and executive committee was made. The ACR and SBI strongly criticized the Task Force recommendations, disagreed with the conclusions drawn from their analyses and with their methods for formulating their recommendations. The two bodies firmly stand by their recommendation to begin annual screening mammography at the age of 40 for women at average risk for breast cancer.

Their recommendations for screening mammography are as follows:

• Age 40
  - Women at average risk
• Younger than age 40
  - BRCA1 or BRCA2 mutation carriers: by age 30, but not before age 25
  - Women with mother or sister with pre-menopausal breast cancer: yearly screening starting at age 30 but not before age 25, or 10 years earlier than the age of diagnosis of relative, whichever is later
  - Women with greater than or equal to a 20 percent lifetime risk for breast cancer on the basis of family history (both maternal and paternal): yearly starting by age 30 but not before age 25, or 10 years earlier than the age of diagnosis of the youngest affected relative, whichever is later
  - Women with history of mantle radiation received between the ages of 10 and 30: beginning eight years after the radiation therapy but not before age 25
  - Women with biopsy-proven lobular neoplasia, ADH, DCIS, invasive breast cancer, or ovarian cancer, regardless of age

Their recommendations for age at which breast cancer screening should end are as follows:

• When life expectancy is less than five to seven years on the basis of age or comorbid conditions
• When abnormal results of screening would not be acted on because of age or comorbid conditions

Evidence to support the recommendations for routine screening mammography came from the results of RCTs conducted in the United States, Canada, and Europe, including nearly 500,000 women. The trials included women of different ages and different screening frequency; all but one demonstrated decreases in breast cancer mortality among those invited to screening. Overall, these studies demonstrated a 26 percent reduction in mortality.⁹ More recent Swedish studies of screening mammography in routine use (service screening) demonstrated even greater benefits,^{7, 10} estimating that 75 percent of the mortality reduction was due to mammographic screening.

Support for Recommendations

A perspective published in December of 2009 in the New England Journal of Medicine written by Drs. Partridge and Winer¹¹ conveys agreement by logically deciphering the task force recommendations one by one. The authors recognize the reduction in breast-cancer mortality in women aged 40 to 74 due to screening, the injustice of one third of American women not having regular screening due to health care or poor education, and that mammography is highly imperfect (missed cancer, false positives, and over-diagnosis of non-invasive cancers).

They give a practical interpretation of the guidelines and incorporate how patients should be advised. They first discuss how the Task Force did not intend to turn breast cancer screening for women in their 40s upside down; their recommendations reflecting only a modest adjustment. The authors re-iterate that the Task Force is not prohibiting mammography or stating that it has no value. The Task Force is attempting to point out that benefits from mammography are limited in younger women and further that those at average or minimal risk should make the decision to screen with their health care providers.

Partridge and Winer’s perspective also points out that the recommendations should be viewed as a step towards a more personalized cancer screening, screening tailored to personal risk assessments. The authors emphasized how the progress in breast cancer awareness and screening should not be reversed due to debate over the Task Force findings and that educational efforts must be continued and even increased in some areas. When considering change in reimbursements from insurance carriers, they feel that this should only be considered after “broad consensus about the risk and benefits of screening in well-defined subgroups” is defined and at present feel that no woman in her 40s should be denied coverage for screening mammography.

Woolf’s commentary¹² supported the Task Force effort and discussed the lessons learned after legislation was passed to override the USPSTF recommendations. Such lessons include that scientific panels should communicate clearly when releasing recommendations, the need for intelligent public debate, and understanding the crucial need for independent panels in the assessment of health care guidelines. Woloshin and Schwartz¹³ discuss the benefits and harms of screening, emphasizing over-diagnosis. They stressed the importance of women, along with their physician, considering the harms and benefits of screening, pointing out the need of balanced public information (harms and benefits), and that medical care should not be a political issue.

Dr. Murphy¹⁴ discussed mammography screening from two perspectives: as a breast cancer advocate and as a member of the academic medical community. She discusses the need for honest education regarding the risks and benefits of mammography, especially within the 40 to 49 age group. Dr. Murphy stressed the importance of risk assessments to determine the individualized need to screen. She further emphasized the importance of clinicians educating their patients regarding the USPSTF recommendations as well as the advocacy organizations such as the ACS, and discusses the need for breast cancer researchers to develop sensitive and specific tools for early diagnosis while addressing over-diagnosis and unnecessary treatment.

Conclusion

The newest recommendations issued by the USPSTF resulted in confusion for both physicians and patients. Many experts in the field of breast imaging have come out both in support of and in opposition to the new recommendations. Those against have argued that the task force did not use the important science available, and additionally placed too much emphasis on the “harms” associated with screening, rather than the “harms” associated with not screening. Those who support the Task Force recommendations have made a variety of comments; some have stated that the recommendations are simply an adjustment to the previous recommendations, and further that they should be viewed as a step towards a more personalized screening system. Whichever side of the argument one falls on, one point remains clear: screening for breast cancer should not stop. The most important goal should remain decreasing breast cancer mortality.

Stamatia Destounis, MD, is managing partner and a radiologist at Elizabeth Wende Breast Care in Rochester, NY. 

References
1. Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2009; 151:716-726.
2. Lee CH, Dershaw DD, Kopans D, Evans P, Monsees B, Monticciolo D, et al. Breast Cancer Screening With Imaging: Recommendations From the Society of Breast Imaging and the ACR on the Use of Mammography, Breast MRI , Breast Ultrasound, and Other Technologies for the Detection of Clinically Occult Breast Cancer. J Am Coll Radiol 2010; 7:18-27.
3. Hendrick RE, Helvie MA. United States Preventive Services Task Force Screening Mammography Recommendations: Science Ignored. AJR 2011; 196: W112-W116.
4. DeAngelis CD, Fontanarosa PB. US Preventive Services Task Force and Breast Cancer Screening. JAMA 2010; 303(2):172-173.
5. Berg WA. Benefits of Screening Mammography. JAMA 2010; 303 (2): 168-169.
6. Tabar L, Fagerberg G, Chen HH, Phil M, Duffy SW, Smart CR, et al. Efficacy of Breast Cancer Screening by Age. Cancer 1995; 75(10): 2507-2517.
7. Tabar L, Vitak B, Chen THH, Yen AMF, Cohen A, Tot T, et al. Swedish Two-County Trial: Impact of Mammographic Screening on Breast Cancer Mortality during 3 Decades. Radiology 2011 110469; Published online June 28, 2011, doi:10.1148/radiol.11110469.
8. Thrall JH. US Preventative Task Force Recommendations for Screening Mammography: Evidence-Based Medicine or the Death of Science? JACR 2009, Published online, doi:10.1016/j.jacr.2009.11.019.
9. Kerlikowske K, Grady D, Rubin SM, Sandrock C, Ernster V. Efficacy of screening mammography. A meta-analysis. JAMA 1995; 273:149-54.
10. Duffy SW, Tabar L, Chen H, Holmqvist M, Yen MF, Abdsalah S et al. The impact of organized mammography service screening on breast carcinoma mortality in seven Swedish counties. Cancer 2002; 95:458-69.
11. Partride AH, Winer EP. On Mammography-More agreement Than Disagreement. NEJM 2009; 361 (26): 2499-2501.
12. Woolf SH. The 2009 Breast Cancer Screening Recommendations of the US Preventive Services Task Force. JAMA, 2010; 303(2): 162-163.
13. Woloshin S, Schwartz LM. The Benefits and Harms of Mammography Screening: Understanding the Trade-offs. JAMA 2010; 303 (2): 164-165.
14. Murphy AM. Mammography Screening for Breast Cancer: A View From 2 Worlds. JAMA 2010; 303(2): 166-167.