The American Cancer Society’s new guidelines for mammograms were released on Tuesday, reigniting the debate over when and how often women should undergo the screening procedure. The new guidelines, published in the Oct. 20 issue of the medical journal JAMA, are just the latest in a series of revisions and updates to national breast cancer screening guidance, and they’ve raised many important questions for women.
To cut through the confusion, here’s a breakdown of seven important things that you need to know:
1. What do the new guidelines say?
The new ACS guidelines recommend that women of average breast cancer risk begin regular screenings at age 45, a change from their previous recommendation of 40. Annual mammograms are recommended for women between ages 45 and 54, but once a woman turns 55, these annual screenings should slow to every other year, the ACS said. Although they don’t recommend it, the ACS did emphasize that women in their early 40s should still be able to get mammograms if they want them, as long as they understand the risks.
2. Who are the guidelines for?
It’s important to note that these guidelines are only for women with an average risk for breast cancer and do not apply to women with a personal history of breast cancer, a confirmed or suspected genetic predisposition to cancer (like the BRCA gene mutation), a family history of breast cancer, or a history of receiving radiotherapy to the chest at a young age (say, for the treatment of pediatric cancer).
3. What was the impetus for the changes?
The expert panel who led the development of the new guidelines explained that they were crafted in the hope that women will learn about both the potential benefits and downsides of breast cancer screenings. Although mammography continues to save many lives, increasing evidence on the risks associated with mammography indicated a need to reevaluate the timing of screening guidelines, the ACS said.
4. How did the ACS come up with the new guidelines?
The ACS made their recommendations after first convening two expert panels to conduct separate research reviews, and then consulting with other independent experts and medical groups to develop the specific guidance. The first research review was led by a group of 12 interdisciplinary breast cancer experts, who evaluated the state of the science on the benefits and risks of breast cancer screening. To weigh annual versus biennial screening, the ACS commissioned a separate study from the Breast Cancer Surveillance Consortium, part of the National Cancer Institute. The teams gathered a mix of randomized controlled trials, observational studies and simulation studies published since 2000 to come to a consensus on the optimal ages for screening, and then sent the guidelines to 26 outside organizations and 22 expert advisors for review and feedback.
5. What are the potential risks of mammography?
One of the most common harms that can come from breast cancer screening is the chance of false “recall” — when women are told they might have something and are asked to submit to more testing, when really there is nothing wrong. On average, about 10 percent of women who undergo screening will be recalled for more testing, but only five out of 100 recalled women will actually have cancer, according to the National Institute of Health’s National Cancer Institute. Over time, this risk adds up: Among women who have been screened annually for the past ten years, 50 percent will have at least one false positive, and about seven to 17 percent of these women with false positives will undergo a biopsy for further testing. Recalls and false positives can cause unnecessary anxiety in women — anguish they would have never felt if they hadn’t been screened in the first place.
A much more serious risk of breast cancer screening is overdiagnosis and overtreatment of breast cancer, or when women are diagnosed with cancer and treated even though the cancer would not have caused the woman any symptoms or harm in her lifetime. Women who are overdiagnosed with breast cancer will endure difficult and risky cancer treatment, which can include disfiguring surgery and invasive treatments like chemotherapy and radiotherapy that could even cause future cancer — all over a growth that never would have caused any problems if left undetected. One 2012 study published in the Lancet medical journal found that for every life saved by a mammography screening, an estimated three women will unnecessarily be treated for breast cancer.
6. Why is the ACS now recommending annual mammograms starting at 45, not 40?
Researchers weighing the evidence looked at the benefits and risks in five-year intervals, rather than the usual 10-year intervals, and determined that a 40-year-old’s risk of breast cancer was low—closer to a 30-year-old’s than 50-year-old’s—and there was a far greater likelihood that screening women in their early 40s would have a false-positive result than find cancer. However, the risk of breast cancer starts to be high enough at age 45 that women should be all screened annually. By raising the age of the first mammogram screening from 40 to 45, the researchers hope that the number of false-positive findings will go down. This is not just because fewer screenings mean fewer discoveries, but also because younger women have denser breasts that lead to a higher false recall rate.
7. Why did the ACS decide on biennial screening for women after age 55, after recommending annual mammograms for so long?
In the study conducted by the Breast Cancer Surveillance Consortium, researchers found that younger women benefited from annual screening because their cancers, though rare, tend to be more aggressive. Tumors in postmenopausal women tend to grow slowly enough that annual screening has only a small benefit over biennial screening, but adds significantly to the risk of false positives. The ACS cited a long-term study from 2011 that found switching from annual screenings to biennial screenings would decrease the incidence of at least one false-positive recall and false-positive biopsy by 32 percent and 31 percent, respectively.
8. How do the new guidelines stack up against those of other leading medical groups?
They’re similar to the guidelines set forth by the United States Preventive Services Task Force (USPSTF) in 2009, as well as European health authorities’ 2003 recommendations, which suggest screenings every two years for middle-aged women (although the USPSTF recommends that women start getting regular mammograms at age 50, not age 45). The U.K.’s National Health Service offers free mammograms to women ages 47 and up every three years. However, the American College of Obstetricians and Gynecologists still recommends that women start getting mammograms at age 40 — an age that the ACS says is too early, given the balance of risks and benefits.
An estimated 230,000 women will be diagnosed with breast cancer in 2015, and some 40,300 women are expected to die of the disease this year. But thanks to advances in treatment and widespread screening, breast cancer deaths have declined steadily over the past 25 years. Experts agree that mammography remains the best way to screen for breast cancer, and the new ACS guidelines don’t change the fact that mammograms can and do save lives; rather, they are just more fine-tuned to make sure the benefits are maximized and harms minimized.