What Are The Breast Cancer Screening Guidelines?
Breast cancer is a principal cause of early mortality among US women. For this reason, early detection of breast cancer is key. Early detection has been to linked with reduced breast cancer morbidity and mortality. Breast cancer remains second, after lung cancer, as the highest cause of cancer death in women in the United States. In 2012, deaths from breast cancer accounted for 783,000 years of potential life lost and an average of 19 years of life lost per death. Even though mortality from breast cancer has declined steadily since 1990, largely due to improvements in early detection and treatment.
According to the 2015 JAMA journal which outlined and updated the 2003 guidelines there is now greater emphasis on estimating “harms associated with screening; assessing the balance of benefits and harms; and supporting the interplay among values, preferences, informed decision making and recommendations.” In 2011, the American Cancer Society incorporated standards suggested by the Institute of Medicine into its guidelines development protocol to ensure a more reliable, transparent, and consistent process for evolving and communicating guidelines.
These guidelines are for women at average risk for breast cancer. A woman at average risk does not have a personal history of breast cancer, a family history of breast cancer, a genetic mutation known to increase the risk of breast cancer (such as BRCA) and has not had chest radiation therapy before the age of 30.
- Women between 40 and 44 have the option to start screening with a mammogram every year.
- Women 45 to 54 should get mammograms every year.
- Women 55 and older can switch to a mammogram every other year, or they can choose to continue yearly mammograms. Screening should continue as long as a woman is in good health and is expected to live 10 more years or longer.
According to the breast cancer screening guidelines women who are at high risk for breast cancer based on certain factors should get an MRI and a mammogram every year. This includes women who have a lifetime risk of breast cancer of approximately 20 to 25 percent or greater, according to risk assessment tools that are based mainly on family history such as:
- Have a known BRCA1 or BRCA2 gene mutation
- Have a first-degree relative (parent, brother, sister or child) with a history of breast cancer
- Had radiation therapy to the chest when they were between the ages of 10 and 30 years
- Have Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome or have first-degree relatives with one of these syndromes
The American Cancer Society recommends against MRI screening for women whose lifetime risk of breast cancer is less than 15 percent.
The American Cancer Society’s breast cancer screening guidelines aim to provide guidance to the public and healthcare professionals. It is encouraged that women be aware of these guidelines and discuss their family and medical history with their physician. The aim of these breast cancer screening guidelines is to maximize the reduction of breast cancer mortality and to find cancer as early as possible. These guidelines were created so that “all women [can] understand what a mammogram can and cannot do.” This highlights the fact that though mammography has its strengths, it also has its weaknesses.
- False Positive results: Imaging sometimes leads to follow-up examinations, including biopsies, when there is no cancer. A false-positive is most likely following a woman's initial screening mammogram. Other factors that increase the likelihood of a false-positive include having dense breast tissue, which is 50 percent of women. On average, 10 percent of women will be recalled from each screening examination for further testing, but only 5 percent of these women will have cancer.
- False Negative: False-negative results occur when mammograms appear normal even though breast cancer is present. Overall, screening mammograms miss about 20 percent of breast cancers that are present at the time of the screening. The main cause of false-negative results is high breast density. Breasts contain both dense and fatty tissue, with dense tissue appearing white on a mammogram, just as a tumor would. Finding cancer in dense breasts has been likened to finding a snowball in a snowstorm. False negative results can lead to delays in treatment and a false sense of security for affected women and their families.
- Overtreatment and Overdiagnosis: overtreatment and overdiagnosis might be caused by screening mammograms that lead to medical interventions for certain cases of ductal carcinoma in situ (DCIS) that may never have become clinically apparent, would not have caused a woman any harm in her lifetime, would not have progressed or needed treatment, or otherwise been detected in the absence of screening.
- Radiation exposure: Overall risk from a single exposure from mammography is very small. However, the risk increases with the amount of exposure and with exposure at younger ages.
- Variability of Pathologists’ Diagnoses on Interpretation of Biopsy Specimens: The pathologist’s diagnosis of breast tissue ranges from benign without atypia, to atypia, to DCIS, to invasive breast cancer. The incidence of atypia and DCIS breast lesions has increased over the past three decades as a result of widespread mammography screening. Misclassification of breast lesions may contribute to either over treatment or under treatment of lesions identified during breast screening.
How can we complement mammography to reduce the weaknesses?
We can complement imaging through the addition of a blood-based approach to the current standard-of-care. A blood-based approach would give women peace of mind and save costs on unnecessary biopsies, while also saving the health care system as a whole money by reducing unnecessary invasive procedures. A blood-based approach would also allow women with difficult-to-interpret results and dense breasts to gain a definitive diagnosis as the test would be based on physiology rather than anatomy, this would thus reduce false positive and negative results. Overdiagnosis would be reduced by catching cancer in real time, as early as possible. Though the breast cancer screening guidelines to not currently include this form of approach, if they were to be updated to include a blood-based approach to the current standard-of-care women, healthcare professionals and the healthcare system as a whole would all benefit.