Diana Zuckerman, PhD and Anna E. Mazzucco, PhD, Cancer Prevention and Treatment Fund
In recent years, there has been a growing concern that annual mammograms starting at age 40 may do more harm than good for many women. That is why the U.S. Preventative Services Task Force, an expert group that reviews the latest research findings, recommends that mammography screening for most women start at age 50 rather than 40, and that the frequency be every two years (instead of annually) through the age of 74.
The Task Force is widely used as a gold standard for determining medical treatment and screening. In this case, they recommended raising the age to 50 after the American College of Physicians recommended the same thing, and they also recommended that women continue to undergo mammograms until age 74. They say that there is no evidence of what the benefits might be for women 75 and older.
For many years, the American Cancer Society (ACS) recommended annual mammograms starting at age 40, but in October 2015, they issued new recommendations that moved in the direction of those of the medical experts. They now recommend that women at average risk of breast cancer start mammography at 45, that they undergo annual mammograms from 45 – 54, and continue to undergo mammography every other year after that. In contrast, some experts point out that screening mammograms usually do more harm than good, because there is no evidence that they save lives or result in less radical surgery. Experts do not recommend MRIs for screening women of average risk, but clinical studies are being done to determine whether they should be.
So What Is Best for You?
A key reminder: These recommendations are for screening mammograms. Mammograms are still needed at almost any age if a lump is found. The mammography recommendations also do not apply to all women, only for the average woman. Experts agree that women at especially high risk of breast cancer, such as those with mothers or sisters who had breast cancer, may want to start mammograms between the ages of 40 and 50 or in rare cases, even earlier.
The bottom line is that mammograms have the potential to help detect breast cancer earlier. However, like most medical procedures, there are risks as well as benefits.
Whether to start at age 50, age 40, or earlier or later or never depends on several different factors.
For most women, who are not at especially high risk of breast cancer, regular mammograms do not need to start before age 50. Or, to be cautious, a woman can get one mammogram earlier (around age 45), and then if it is normal, wait until she is 50 for her next mammogram. This is the advice that the National Center for Health Research and their Cancer Prevention and Treatment Fund have been giving since 2007.
Women at higher risk of breast cancer should not wait until they are 50 to have regular mammograms. Please remember that the higher age– 50– is only a guideline (not a strict rule), and only for women with no symptoms and who are not at high risk of breast cancer. In addition, if a woman finds a lump on her breast, a mammogram is still very important, regardless of the woman’s age. For a woman at high risk of breast cancer because of her family history or environmental exposures, regular screening before age 50, or even before age 40, may be a very good idea.
Women who are carriers of the BRCA genetic mutation were previously recommended to begin yearly mammograms between ages 25-30, since this mutation puts them at much higher risk of getting breast cancer. Newer studies have found that starting yearly mammograms before age 35 has no benefit and may instead be harmful. Women end up with higher exposure to radiation from mammograms over their lifetime, which increases their chance of getting radiation-induced breast cancer that they may not have gotten otherwise.
Most women who have a mother, sister, or grandmother who had breast cancer at the age of 50 or older, or who are at high risk of breast cancer because of obesity or other reasons, may want to have regular mammograms (every two years) starting between ages 40 and 50. If their relatives had breast cancer at a young age, women may consider mammograms even before age 40. Unfortunately, younger women tend to have denser breasts, which often look white on a mammogram. Since cancer also shows up as white, mammograms are less accurate for younger women (and other women with dense breasts). For those women, a breast MRI is likely to be more accurate than a mammogram, and they are safer than mammograms.
Breast MRIs are more expensive than mammograms, costing an average of $2,000 (compared to about $100 for a mammogram). The Task Force says there isn’t enough information to recommend for or against MRIs. For that reason, insurance may not cover the cost. If you want insurance to pay for an MRI, you probably need your doctor to recommend it because of your high risk. Women with dense breasts are at higher risk, especially women with mothers or sisters who had breast cancer at a young age. It is logical that they could potentially benefit from regular breast MRIs, but research is lacking to draw conclusions.
Which Kinds of Cancer Risks Can Help Me Decide?
A 2011 article by Dr. John Schousboe and his colleagues examined mammography for women at different ages and with different risk factors. They concluded that mammography screening once every two years (biennial) had health benefits and was cost effective for all women 40-79 with high breast density or with both a family history of breast cancer and a breast biopsy, regardless of breast density. Biennial mammography was also beneficial for women aged 50-69 with average breast density and women 60-79 with low breast density and either a family history of breast cancer or a previous breast biopsy. Annual mammography was not cost-effective for any group.
The study’s authors concluded that each woman’s decision about mammography screening should be based on the following risk factors: age, breast density, history of breast biopsy, family history of breast cancer, and personal beliefs about the benefits and harms of screening. This study supports the Task Force guidelines that women at an average risk of breast cancer can start biennial screening at age 50, and that women at a higher breast cancer risk should consider screening before age 50.
The chances of getting breast cancer increase with age, and the disease is much more common after age 50. So, from a public health and cost-effectiveness perspective, annual screening mammograms do the most good after age 50. Earlier mammograms are less accurate and more likely to result in unnecessary anxiety or unnecessary biopsies. Unlike Schousboe and his colleagues, the Task Force did not recommend routine screening for women 75 and older, because there was not enough evidence to conclude whether or not the benefits outweigh the risks. However, the American Cancer Society recommends that screening every other year continue for older women whose health is good enough that they are likely to live at least 10 years. That is a difficult standard to implement: How many doctors want to tell their healthy older patients that they don’t need mammography because they are not likely to live at least 10 more years?
Isn’t More Frequent Mammography Better?
Remember that mammograms expose women to radiation, which can increase the risk of breast cancer. Increasing the age of mammograms to age 50 for most women, and reducing the frequency to every two years could save lives because it would drastically reduce radiation exposure. Experts believe that less frequent mammograms also means a lower false alarm rate, and that means fewer unnecessary tests, anxiety, and possibly fewer unnecessary surgeries.
The Big Debate: Do Mammograms Save Lives?
Between 1975 and 2000, dramatic improvements in treatments for breast cancer became available. Surgery options were improved, important chemotherapy agents were discovered, and tamoxifen, a hormonal treatment for estrogen-sensitive breast cancer, came into widespread use. At the same time, mammography became more popular. In 2000, about 70% of women 40 and over reported that they had a mammogram within the previous two years. Mammography rates more than doubled between 1987 and 1999, but more recently rates have decreased slightly.
The result of these important advances has been a dramatic decrease in the number of breast cancer deaths, even while more cases of breast cancer were being diagnosed. The five-year survival rate for breast cancer increased from 75% between 1974 and 1976, to 91% between 2005 and 2011. Have the survival rates improved because of mammography or because of better treatments?
This became a full-fledged medical controversy in recent years. Two issues were at the root of the debate: 1) Was mammography simply uncovering more tiny, slow-growing abnormalities or cancers that would never have developed into a health threat even if they had never been discovered? and 2) Were we doing more harm than good by subjecting so many women to cancer treatment without knowing whether some of these breast abnormalities or very early cancers would really become dangerous? Since 2009, researchers have debated whether some tiny cancers disappear on their own without treatment. More important, experts agree that most ductal carcinoma in situ (DCIS) will never become an invasive breast cancer, even without treatment.
Regular screening mammography can possibly help diagnose cancer earlier, but the latest research suggests it may not have as much benefit for earlier diagnosis as expected. In January 2017, the Annals of Internal Medicine published a Danish study which examined whether the use of mammography can prevent the number of bigger, more advanced cancers that are difficult to treat.5 Dr. Karsten Juhl Jorgenson and colleagues looked at 30 years of data and compared women living in areas covered by screening programs to those in areas without the programs. Overall, mammography was not associated with fewer advanced cancers. However, in the areas with screening programs, diagnoses of non-advanced cancers increased. It is estimated that up to one third of diagnosed breast cancer cases would never have caused noticeable health problems or death.
Other research indicates mammography may not be saving lives, except possibly for the highest risk women. Researchers estimate that for 1,000 40-year-old women who have annual mammograms, two fewer women will die of breast cancer. During that time, approximately 600 of these 1000 women will have false alarms, and approximately 5 – 10 will have unnecessary surgical treatment that could be harmful to them. This latest research did not consider the benefits compared to the risks of regular mammography (every two years) after age 50. It is possible that starting less frequent mammography at 50 (and for women at high risk between the ages 40 and 50) could provide benefits that may outweigh the risks for most women. Although about 90% of worrisome findings from mammograms turn out to be false alarms — not cancer — many experts continue to believe that the overall benefits have been established for women over 50.
Having fewer women die of breast cancer does not, however, mean that fewer women die. None of the studies that evaluate the impact of mammography do so in terms of lives saved. Instead, they evaluate the number of women who die of breast cancer specifically.
What about breast self-exams? The Task Force recommends against teaching women to do breast self-exams, because evidence suggests the risks outweigh the benefits. There are many “false alarms,” and by the time a cancer is large enough to be felt in a self-exam, it will soon be found anyway, in the shower or while dressing. The Task Force and the American Cancer Society no longer recommend that doctors do breast exams on their patients for the same reason. Nevertheless, women should be familiar with how their breasts normally look and feel and report any changes to a doctor right away.
For more information:
U.S. Preventive Services Task Force, Breast Cancer Screening Final Recommendations, http://screeningforbreastcancer.org
For information about insurance coverage for free mammograms: http://www.hhs.gov/blog/2016/01/11/bottom-line-mammograms-are-still-covered.html
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
- BMJ 2016;352:h6080
- Berrington de Gonzalez A, Berg CD, Visvanathan K, and Robson M. (2009). Estimated Risk of Radiation-Induced Breast Cancer From Mammographic Screening for Young BRCA Mutation Carriers. Journal of the National Cancer Institute, 101(3): 205-209. doi:10.1093/jnci/djn440
- Schousboe JT, Kerlikowske K, Loh A, and Cummings SR. (2011). Personalizing Mammography by Breast Density and Other Risk Factors for Breast Cancer: Analysis of Health Benefits and Cost-Effectiveness. Annals of Internal Medicine, 155:10-20.
- Hubbard RA, et al. (2011). Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study. Annals of Internal Medicine, 155(8):481-92.
- Braithwaite D, et al. (2013). Screening Outcomes in Older US Women Undergoing Multiple Mammograms in Community Practice: Does Interval, Age or Comorbidity Score Affect Tumor Characteristics or False Positive Rates? Journal of the National Cancer Institute,105(5):334-341.
- Siegel, RL, Miller, KD, & Jemal, A (2016). Cancer statistics, 2016. CA: A Cancer Journal for Clinicians, 66(1), 7-30. doi:10.3322/caac.21332
- Welch G, et al. (2013). Quantifying the benefits and harms of screening mammography. JAMA Internal Medicine.