Diana Zuckerman, Ph.D. and Anna E. Mazzucco, Ph.D.
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 more than two years after the American College of Physicians recommended the same thing, and they also recommended that women continue to undergo mammograms until age 74 instead of stopping at 69. The American Cancer Society strongly disagrees and is still recommending annual mammograms for women over 40.
The American Cancer Society also recommends regular breast MRIs in addition to mammograms for women over 40 at high risk for breast cancer, and as a possible follow-up for abnormalities found by mammogram. 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: the Task Force recommendation is for screening mammograms. Mammograms are still needed at almost any age if a lump is found. The recommendation also does not apply to all women, only for the average woman. Women at especially high risk may want to start mammograms at age 40 or even earlier.
The bottom line is that annual mammograms help detect breast cancer early and improve the chances that it can be treated successfully. However, like most medical procedures, there are risks as well as benefits.
Whether to start at age 50, or 40, or even earlier depends on several different factors.
For most women, who are not at especially high risk of breast cancer, regular mammograms can start at age 50. Or, to be cautious, a woman can get one mammogram earlier (around age 40 or 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 screening women with no symptoms and not at high risk of breast cancer. If a woman finds a lump on her breast, a mammogram is still very important, regardless of the woman’s age. In addition, 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 for mammograms over their lifetime, which increases their chance of getting radiation-induced breast cancer that they may not have gotten otherwise.1
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, should have regular mammograms (every one or two years) starting at age 40. If their relatives had breast cancer at a young age, women need to 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 especially 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 published in the Annals of Internal Medicine examined mammography for women at different ages and with different risk factors. Biennial mammography (screening once every two years) 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 50.2
The chances of getting breast cancer increase with age, and the disease is much more likely after age 50 than before. 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. It will be interesting to see if the Task Force changes that recommendation because of the new study.
Isn’t more frequent mammography better, if I can afford it?
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.34
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 overreported 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. In 2008 about 68% of all women 40 and overreported a mammogram in the previous two years.5
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 88% by 1995-2000. 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 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 very early cancers would really become dangerous? (See Should Women Undergo Mammograms for more details about this debate.) In 2009, a new addition to the controversy was the finding that some tiny cancers disappear on their own without treatment. For example, experts now conclude that about half of ductal carcinoma in situ (DCIS) will never become an invasive breast cancer, even without treatment.
Regular screening mammography helps diagnose cancer earlier but is not saving as many lives as experts hoped. The most recent research estimates that for 40-year-old women, fewer than 2 lives will be saved out of 1000 women who have annual mammograms.6 During that time, approximately 600 of these 1000 women will have false alarms, and approximately 5-10 will have unnecessary surgical treatment. For 50- and 60-year-old women, the number of lives saved would increase to possibly 3 and 5 out of 1000, respectively, again with most women experiencing false alarms and possibly as many as 14 or 20, respectively, having treatment they didn’t need. This latest research did not consider the benefits compared to the risks of regular mammography (every two years) after age 50. We believe that starting less frequent mammography at 50 (and for women at high risk at 40 years of age) continue to provide benefits that outweigh the risks for most women. Although about 90% of worrisome findings from mammograms turn out to be false alarms — not cancer — the overall benefits have been established for women over 50, and for women at high risk who are over 40.
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. And the Task Force concludes that there is not enough evidence to recommend that doctors do breast exams on their patients, for the same reason.
U.S. Preventive Services Task Force, Screening for Breast Cancer: Recommendation Statement,http://www.ahrq.gov/clinic/uspstf09/breastcancer/brcanrs.htm#update
Screening Mammography for Women 40 to 49 Years of Age, available from the American College of Physicians at http://www.annals.org/cgi/content/summary/146/7/511
- 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. ▲
- Centers for Disease Control and Prevention, National Center for Health Statistics. Health, United States, 2009: With Special Feature on Medical Technology. Hyattsville, MD. 2010. Available at:http://www.cdc.gov/nchs/data/hus/hus09.pdf ▲
- Welch G, et al. (2013). Quantifying the benefits and harms of screening mammography. JAMA Internal Medicine. ▲