If there’s one thing that experts can agree on, it’s that breast screening helps to identify cancer at an early stage. For a woman with average risk — a 1 in 8 chance of developing breast cancer during her lifetime — “The primary benefit of early detection is that the cancer is more likely to be treatable,” says Payal D. Shah, MD, a medical oncologist and researcher at the Abramson Cancer Center at the Penn Medicine in Philadelphia.
But breast cancer screening recommendations from three national organizations — the American College of Obstetricians and Gynecology, the American Cancer Society, and the U.S. Preventive Services Task Force — are at odds when it comes to deciding the age to start screening, how often to screen, and when to stop.
Dr. Shah notes that the key is shared decision-making, adding that although most providers will begin the screening discussion when a patient turns 40, it is also “perfectly appropriate for a woman to be proactive.”
Where to Start: Know Your Risk
Risk calculators such as the Breast Cancer Risk Assessment Tool (BCRAT) provide important information that helps a provider make screening recommendations. Factors such as age, reproductive history, previous breast cancer, precancerous breast conditions, or prior chest radiation inform an individualized breast cancer screening strategy, especially for women who might benefit from genetic counseling and supplemental screening modalities.
Ultimately, screening should be based on personal preferences, and the advantages and disadvantages of each approach. But for women of average risk, Jaime Geisel, MD, a radiologist at Smilow Cancer Hospital Care Center at Yale New Haven Hospital in New Haven, Connecticut, says that she recommends starting screening at age 40, repeating every one to two years depending on personal risk factors and desires, and continuing for as long as a woman is in good health.”
For women considered higher-risk for breast cancer based on genetics, prior diagnosis, or a history of radiation therapy at a young age, the American College of Radiology recommends screening earlier than age 40. Supplemental screening modalities like breast magnetic resonance imaging (MRI), contrast-enhanced breast MRI, and ultrasounds can be considered.
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Clinical Breast Examination and Breast Self-Awareness
Clinical breast examination (CBE) is usually performed during a yearly gynecologic or primary care checkup. During a CBE, the provider carefully examines the breasts and around the armpits for unusual dimples, skin changes, or lumps that possibly indicate cancer. Like screening guidelines, there is disagreement about CBE’s value, namely because of the high likelihood of false-positives (results that incorrectly indicate cancer), according to a review published March 2019 in the journal Obstetrics and Gynecology Clinics of North America.
Some providers also recommend that women become breast self-aware (knowing how breasts normally look and feel so changes are more obvious). While BSE empowers women to take control of their health, it’s unclear whether or not it’s actually effective for cancer detection; a comprehensive review published in February 2017 in the Cochrane Database of Systematic Reviews found little evidence favoring its use.
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Screening Mammography (Full-Field Digital Mammography)
Screening mammography is the most commonly used imaging test for average-risk asymptomatic (without symptoms) women according to the American College of Radiology's 2017 Breast Cancer Screening Recommendations. Most screening facilities have replaced older, film-based mammography with full-field digital mammography (FFDM), which relies on digital detectors to convert X-rays into electrical signals, resulting in clearer images.
While research published in February 2016 in the Annals of Internal Medicine confirms that mammography decreases numbers of cancer deaths, and extends length and quality of life, some experts argue that better data is needed to more accurately determine by how much.
Mammography is not without challenges. It may identify harmless or benign cancers that would have never caused problems, resulting in overdiagnosis. Mammography often fails to detect cancers in women with dense breasts). Additionally, it’s linked to an "interval cancer" rate (cancer that becomes clinically obvious between screening) of 30 to 50 percent, according to a review published in February 2017 in Radiology. Finally, some women find the procedure uncomfortable, and worry about radiation exposure.
Digital Breast Tomosynthesis (3D Mammography)
Digital Breast Tomosynthesis (DBT) is an advanced form of mammography screening that provides a 3D image of the breast. DBT is usually conducted in combination with FFDM, using both a low-dose X-ray system and computer reconstructions of the breasts to create the image. Depending on the center, women with concerns about additional radiation exposure may be able to switch out FDDM with synthetic (2D) mammography, a method that uses the images obtained from DBT to reconstruct 2D images.
On the pro side, DBT overcomes many of the limitations of 2D mammography. It can increase cancer detection by 27 percent, while reducing false positives by as much as 15 percent, according to research published in April 2013 in Radiology. This makes it more ideal for women with dense breasts. DBT also reduces overall recall rates without compromising accuracy.
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Hand-Held and Automated Breast Ultrasound
Breast ultrasound is a supplemental test that uses high-frequency sound waves to produce an image of internal breast structures and blood flow. It may be recommended if a provider detects a lump during a CBE, or if mammography shows a potential abnormality. Ultrasound is also offered to pregnant women to avoid X-ray exposure.
Like other modalities, ultrasound has limitations; it can result in false positives, is highly dependent on the radiologist performing (and reading) the screening, and is time-consuming. An automated breast ultrasound (ABUS) was developed to address these issues, explains Dr. Geisel explains, but it lacks the ability to home in on one specific area, is cumbersome, and may result in more callbacks versus the hand-held version. On the pro side, it is less painful than mammography and there is no radiation exposure.
Breast Magnetic Resonance Imaging (MRI)
Breast MRI is a supplemental screening tool that is highly effective for early cancer detection. But it is not part of routine screening, and for the most part is reserved for women with a lifetime breast cancer risk greater than 20 percent (such as women with genetic risks). According to research published in October 2019 in Medical Engineering and Physics, MRI has many disadvantages compared with mammography, including lengthy screening time, the need to inject a contrast agent, and high cost.
Future Screening Modalities
A glimpse into the crystal ball highlights improved screening accuracy by harnessing engineering principles like thermal energy (to measure breast surface temperature), artificial intelligence to better identify women with higher risk who can benefit from genetic testing, and enhanced and supplemental surveillance. In the meantime, both Shah and Geisel advise to take charge, speak with their providers, and weigh the pros and cons carefully.
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