When should you start getting mammograms to screen for breast cancer? How often should you get them done? And what kind of test is best?
These questions might seem straightforward, but expert organizations make different recommendations. Some say start at 40 and get mammograms annually. Others say start at 50 and repeat every other year. This makes it hard to know which advice to follow. But the guidelines all agree that ultimately the choice is up to you, so it’s important to understand the benefits and drawbacks.
“Our new guidance considers each individual patient and her values,” Christopher Zahn, MD, of the American College of Gynecologists (ACOG) said when the group released its updated guidelines in June. “We have moved toward encouraging obstetrician-gynecologists to help their patients make personal screening choices from a range of reasonable options.”
Breast cancer is the most common cancer in women after skin cancer and the second leading cause of cancer death after lung cancer. Nearly 253,000 women will be diagnosed with invasive breast cancer, and more than 40,000 will die from it in 2017, the American Cancer Society (ACS) estimates. Breast cancer is uncommon in men, with around 2,500 new cases and fewer than 500 deaths annually.
Most women are diagnosed after age 50, but some younger women get aggressive breast cancer that can grow and spread rapidly. Although white women are slightly more likely to develop breast cancer overall, Black women are more likely to get it before age 45.
Experts and advocates agree that detecting breast cancer and starting treatment early is the best way to prevent disease progression and improve survival. But how early is early enough?
The new screening guidelines from ACOG, a professional organization of providers of women’s sexual and reproductive health care, say that women with average breast cancer risk should be offered annual mammograms beginning at age 40—with an emphasis on shared decision-making between women and their providers—and should start them no later than 50.
The American College of Radiology (ACR) and the Society of Breast Imaging (SBI), associations for radiologists (who do cancer diagnosis) and radiation oncologists (who administer radiation therapy), recommend annual mammograms starting at age 40.
The American Cancer Society, a nonprofit group dedicated to cancer research, education and advocacy, recommend that women at average risk should start annual mammograms at 45, although they can opt to cut back to every other year at 55. Again, women should be given the choice to start screening at 40 if they wish.
The United States Preventive Services Task Force (USPSTF), an expert panel that makes evidence-based recommendations about prevention services, has the most conservative guidelines. In 2015, the USPSTF recommended that women at average risk should receive mammograms every other year starting at 50. But it adds, “Women who place a higher value on the potential benefit than the potential harms” can start screening at 40.
Not all women are average, of course.
Experts agree that some women should start screening sooner and get it done more often because they are at higher risk of developing breast cancer or having more aggressive disease. These include women with the BRCA1 or BRCA2 gene mutations, women with a family history of breast cancer and those taking hormone replacement therapy after menopause.
What about when to stop breast cancer screening?
The ACS says women should continue screening if they are in good health and expected to live for at least 10 years. The ACR says screening should stop when life expectancy falls below five to seven years. ACOG leaves this decision up to women and their doctors, while the USPSTF says there isn’t enough evidence to make a recommendation.
Mammograms may not be the best way to detect breast cancer in all women. Those with dense breasts, for example, may benefit from ultrasound imaging. Breast screening and diagnosis methods include:
Mammography uses low-dose X-rays to create a detailed image of the breast, which is compressed between two plates.
Digital breast tomosynthesis, also known as a 3-D mammogram, takes multiple X-rays from different angles and combines them into a three-dimensional image.
Ultrasound uses high-frequency sound waves from a transducer passed over the breasts. It is better at finding abnormalities in dense breast tissue but has a high false-positive rate.
Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to take detailed internal images of a person inside a tunnel-like scanner. It is not usually used for breast screening but can get more information after an abnormal mammogram.
Thermography measures variations in the temperature of the breasts, which may detect tumors that are a different temperature than surrounding normal breast tissue.
Electrical impedance imaging runs an electrical current through the breast and measures electrical conductivity, which may be different in tumors compared with normal breast tissue.
Molecular breast imaging is a new method that uses an injectable radioactive tracer that makes cancer cells glow under a scanner.
It is important to stress that breast cancer screening guidelines are for preventive screening of women at average risk who show no signs of breast cancer. If you feel a lump in your breast or have other signs, such as a change in breast shape or unusual discharge from a nipple, contact your provider immediately.
And speaking of lumps, although some experts still advise women to do monthly breast self-exams, there is little evidence that these contribute to improved survival. Regarding clinical manual breast exams by a doctor or nurse, the ACOG recommends getting them done annually, the ACS does not recommend them and the USPSTF recommends against them.
Implications of the Guidelines
Screening guidelines are written by experts who review medical studies and decide whether there is enough evidence to show that the benefits of an intervention outweigh the risks or harms. These decisions are necessarily based on population averages. There is no way for experts to know what the outcome will be for a specific woman—only what is likely to happen for a group of similar women.
The USPSTF guidelines carry particular weight because they are used to determine which prevention services insurance companies are required to cover for free under the Affordable Care Act.
But many providers think the USPSTF guidelines do not reflect the best care. The ACR and SBI claim that the USPSTF relies on “antiquated” methods, basing its recommendations on a limited review of selected studies that are often decades old and used outdated equipment.
“The USPSTF guidelines are based on attempts to save health care dollars and lessen patient anxiety. Much of the data this group relied upon is based on outdated technology,” Anjali Malik, MD, of Washington Radiology in Washington, DC, and a member of the SBI’s communications committee, told Cancer Health.
“Breast cancer affects one in eight women, which means that the average-risk female has a 12 percent risk for the development of breast cancer over the course of her lifetime,” Malik continued. “As we have yet to discover a way to completely prevent or cure the disease, early detection remains the best way to tackle breast cancer, and the way to save the most lives is to start annual screening mammograms at the age of 40.”
The benefits of breast cancer screening are obvious, especially for women older than 50. Several studies have shown that detecting the disease at an early stage and treating it quickly can save lives. But there is less evidence for the benefits of screening for women younger than 50 or older than 75.
The drawbacks of early screening are not always so obvious.
Cost, of course, is a big factor. Some people assume that public health guidelines that recommend later or less frequent screening are simply trying to save money, while professional societies that advise screening more often just want to pad their pockets. Although mammograms aren’t particularly expensive as medical interventions go, screening millions of women adds up.
But cost is not the only factor. Earlier and more frequent screening results in more false positives, meaning suspicious findings that turn out not to be cancer that requires treatment. False alarms can cause anxiety, and follow-up tests such as biopsies take time and money and carry a small but real risk. Some women will be “overdiagnosed” and may undergo “overtreatment”—and suffer its side effects—for small, slow-growing cancers that never would have become life-threatening. And more mammograms means more radiation exposure, which itself can cause cancer.
Experts who favor earlier and more frequent screening say claims about overdiagnosis are exaggerated and most women with suspicious findings usually need only an additional mammogram or ultrasound, not an invasive procedure.
“Screening beginning at 40 and screening every year saves the most lives,” according to Sally Herschorn, MD, medical director of breast imaging at the University of Vermont Medical Center.
“One woman may be willing to have many callbacks and even biopsies in order to insure that if ultimately diagnosed with cancer, that it is caught early, thus giving her the best fighting chance. She would choose to be screened every year beginning at 40 and may even choose additional screening if her breasts are dense,” Herschorn wrote in a blog post sorting out the guidelines. “Another may be put off by the possibility of additional testing and may decide on a more conservative screening schedule, beginning at 45 and screening only every two years. Neither path is incorrect. Each is the right path for that woman.”
The Bottom Line
The conflicting recommendations about when and how often to get screened for breast cancer won’t satisfy women looking for easy answers. But an ongoing study called WISDOM, which plans to enroll about 100,000 women, hopes to improve decision-making in the future.
“We are testing a new way of personalizing screening by doing a comprehensive risk assessment and using that to assign women an age to start and stop, a frequency and a modality,” Laura Esserman, MD, director of the University of California San Francisco Carol Franc Buck Breast Care Center told Cancer Health. “Our goal is to determine if this is safe and associated with fewer interventions and false positives and whether it promotes better value.”
In the meantime, the best advice is to do what most guidelines and providers agree on: Discuss the potential benefits and harms of screening with your provider, along with your individual risk factors and personal preferences so you can make the decision that’s right for you.