Recognizing that the purpose of breast cancer screening is to decrease breast cancer mortality and morbidity, NCCN continues to recommend annual screening mammography beginning at age 40 years for average-risk women. Mammographic screening and subsequent treatment based on those results reduces breast cancer mortality based on a wide range of studies using various methodologies.1–4
Recent publicity emphasizing differences between various mammographic screening recommendations has masked fundamental areas of agreement among major organizations in the United States, all of which recommend routine screening mammography. Analysis by these key organizations, including the American Cancer Society (ACS) and US Preventive Services Task Force (USPSTF), have shown that the maximum mortality reduction and life years gained (LYG) benefit occurs when screening begins at age 40 years.1,2 All of the groups agree that screening mammography is an imperfect test with limitations, especially for women with dense breasts, and all advocate informed patient decision-making regarding screening. Mammographic screening should not be offered to women with limited life expectancy.
This article highlights NCCN's position on screening mammography for average-risk women, emphasizing important factors considered by NCCN, but is not intended as a comprehensive screening review or assessment of emerging supplemental screening technologies covered elsewhere.5 NCCN believes that women electing to undergo screening mammography should be counseled regarding potential benefits, risks, and limitations, and shared decision-making is encouraged.
Breast cancer is a major worldwide health problem. In the United States, 12.5%, or 1 in 8 women, will develop breast cancer during their lifetime. In 2018, an estimated 266,120 cases of invasive breast cancer and 63,960 cases of in situ carcinoma will be diagnosed.6 In contrast, during the same year, 112,350 women will be diagnosed with lung cancer, 26,240 with pancreatic cancer, and 13,240 with cervical cancer.6 Breast cancer is the most common nonskin cancer impacting women: an estimated 40,920 women will die of the disease in 2018.6
Since 1990, the mortality rate in the United States has decreased by a remarkable 39%, which has been attributed to advances in screening, treatment, and early detection.6 An even greater 49% mortality decline is estimated when adjustments are made for existing background mortality trends.7 Invasive breast cancer incidence in the United States has remained stable since the late 1980s.2 In contrast, WHO data shows worldwide mortality and incidence rates increased (2.8% and 4% per year, respectively) from 2008 through 2012.8 The progress made in the United States and other countries is lacking in much of the world.
Why do organizations differ on screening recommendations? In substantial measure, these reveal different subjective value judgements between the benefits (deaths averted or LYG) versus the risks (harms). These differences also reflect whether the perspective is individual or population-based. Screening recommendations differ primarily in terms of age of initiation and frequency of screening, and these differences have caused confusion among women and providers regarding appropriate use of mammography, which may contribute to its current underuse. There has been more consistency regarding the age at which to stop screening and the need to integrate overall patient health in screening decisions.
Table 1 summarizes the guidelines by several major organizations. In 2016, in an attempt to harmonize the various recommendations, the American College of Obstetricians and Gynecologists (ACOG) held a consensus conference in Washington, DC, which included members from NCCN, American Academy of Family Physicians, ACS, American College of Physicians, American College of Radiology, American College of Surgeons, and USPSTF. The goal was to produce a screening document on which all organizations could agree. However, consensus could not be reached due to the differences regarding age of onset and frequency.
The NCCN Breast Cancer Screening and Diagnosis Panel subsequently convened in 2017 and affirmed that the primary purpose of screening is to decrease mortality and treatment-related morbidity. NCCN prioritized the benefits of screening over the known risks. In addition to mortality benefit,
Summary of Average-Risk Screening Mammography Recommendations
A major impediment to organizational consensus is the inability to quantitate the value of a death averted or LYG compared with a nonlethal risk, such as a recall, needle breast biopsy, or potential overdiagnosed cancer. Women have placed a high value on the benefits of mortality reduction compared with the risks. Schwartz et al13 showed that 63% of women thought ≥500 false-positives per life saved was acceptable, and 62% “did not want to take false-positive results into account when deciding about screening.”
Interestingly, since publication of the controversial 2009 USPSTF guidelines, 88% of surveyed internists, family medicine physicians, and gynecologists recommend screening mammography for women aged 45 to 49 years and 81% for women aged 40 to 44 years.14 These results show continued disconnect between certain organizational guidelines and practicing physicians' actions.
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