Breast Cancer Facts & Figures 2019-2020(part 1)
Breast Cancer Risk Factors
The most well-established risk factors for breast cancer are summarized in Table 4. It is estimated that about one-third of postmenopausal breast cancers are linked to potentially modifiable factors, including postmenopausal obesity, physical inactivity, use of combined estrogen and progestin menopausal hormones, alcohol consumption, and not breastfeeding.48 Many risk factors (early menarche, late menopause, obesity, and hormone use) affect lifetime exposure of breast tissue to hormones. Hormones are thought to influence breast cancer risk by increasing cell division, thereby increasing the likelihood of DNA damage, as well as promoting cancer growth. Although exposures that influence risk accumulate throughout a woman’s life, research suggests that earlylife exposures during breast development may be particularly critical.49 Many established risk factors for breast cancer are specifically associated with HR+/ luminal breast cancer; less is known about risk factors for HR-, HER2+ or basal-like breast cancers.50 The following sections present current knowledge about factors associated with breast cancer risk.
Family history and personal characteristics
Family history
Women (and men) with a family history of breast cancer, especially in a first-degree relative (parent, child, or sibling), are at increased risk for the disease. Compared to women without a family history, risk of breast cancer is about 1.5 times higher for women with one affected first-degree female relative and 2-4 times higher for women with more than one first-degree relative.51-53 Risk is further increased when the affected female relative was diagnosed at a young age or was diagnosed with cancer in both breasts, or if the affected relative is male. It is important to note that the majority of women with one or more affected first-degree relatives will never develop breast cancer and that most women who develop breast cancer do not have a family history of the disease.51 A family history of ovarian and perhaps pancreatic or prostate cancer is also associated with increased breast cancer risk.54, 55 Women should discuss their family history with their health care provider because it may signal the presence of a genetic predisposition to cancer and the need for a different plan for screening and risk reduction.
The US Preventive Services Task Force recommends that primary care providers routinely collect and update family medical history, as well as ancestry. Women with a personal or family history of breast, ovarian, tubal, or peritoneal cancer or those with ancestry associated with BRCA1/2 gene mutations should be screened with one of several brief questionnaires to determine if there is a need for in-depth genetic counseling to consider genetic testing.64 Those who consider testing are strongly encouraged to talk with a genetic counselor before making a decision so that the benefits and potential consequences can be understood and carefully considered.
Personal history of breast cancer
Women diagnosed with breast cancer have a small increased risk of developing a new cancer, with estimated 10-year risks ranging from 3%-7%.65 However, rates of subsequent new breast cancers (also referred to as a new primary breast cancer) have declined steadily since 1985.66 The decrease has predominantly been among ER+ breast cancer patients and may reflect the effect of hormonal therapy (e.g., tamoxifen and aromatase inhibitors) and other adjuvant treatments, as well as the rapid increase in breast cancer patients electing bilateral mastectomy for breast cancer treatment (see page 23).65, 67
DCIS and LCIS
DCIS is considered a potential precursor to invasive cancer and risk of subsequent breast cancer is greatest at or near the site of DCIS.68 Similar to women with a prior
What is the difference between absolute, lifetime, and relative risks?
Absolute risk
is the likelihood of being diagnosed with cancer over a certain period of time. For example, the absolute risk of breast cancer increases with age: 12 out of 10,000 women ages 40-44 versus 23 out of 10,000 women ages 50-54 will be diagnosed with breast cancer in the next year.8
Lifetime risk
is the absolute risk of being diagnosed with cancer anytime between birth and death. Lifetime risk of breast cancer reflects the average probability of a female being diagnosed with breast cancer in the US. A woman living in the US has a 13% chance of being diagnosed with invasive breast cancer in her lifetime (Table 2). Another way to say this is that 1 out of every 8 women will be diagnosed with breast cancer in her lifetime.
Relative risk
compares the absolute risk of disease among people with a particular risk factor to the risk among people without that risk factor. If the relative risk is above 1.0, then risk is higher among those with the risk factor than among those without the factor. Relative risks below 1.0 reflect an inverse association between the exposure and the disease, or a protective effect. For example, one study found women ages 50-59 who were current users of combined estrogen and progestin menopausal hormones had a relative risk of developing breast cancer of 1.21, meaning they had a 21% increased risk compared to women who have not used hormone therapy.69 While relative risks are useful for comparisons, they do not provide information about the absolute risk of the exposed group. In this example, 27 breast cancers per year would be expected to be diagnosed among 10,000 women ages 50-59 who had never used menopausal hormones (their absolute risk) compared to 33 breast cancers among 10,000 women of the same ages who had used estrogen and progestin. Thus, the 21% increased relative risk is the equivalent of 6 additional breast cancers per 10,000 women per year.
invasive breast cancer, women diagnosed with DCIS have a small increased risk for developing a new breast cancer. A recent study estimated that 3%-5% of women diagnosed with DCIS were diagnosed with in situ or invasive breast cancer in the opposite breast within 10 years of their initial diagnosis.70
In contrast, LCIS is not generally considered a breast cancer precursor, but is associated with increased risk of developing breast cancer. A recent population-based study of US women diagnosed with LCIS between 1983 and 2014 reported that the 10- and 20-year risk of being diagnosed with DCIS or an invasive breast cancer was 11% and 20%, respectively.71 Notably, the study also reported that the 20-year breast cancer survival in those diagnosed with DCIS or invasive breast cancer exceeded 95%. Pleomorphic LCIS, a more aggressive subtype, is linked to a higher risk of invasive cancer than classic LCIS and is often treated as though it is a cancer precursor.72
Benign breast disease
Benign breast conditions are categorized into 3 general groups reflecting the associated degree of cancer risk: nonproliferative lesions, proliferative lesions without atypia (abnormal cells or patterns of cells), and proliferative lesions with atypia.
Nonproliferative lesions are not associated with overgrowth of breast tissue and include fibrosis and simple cysts (also known as fibrocystic changes) and mild hyperplasia. Nonproliferative conditions are associated with little to no increased breast cancer risk.73
• Proliferative lesions without atypia are associated with a small increase in the risk of breast cancer (1.5 to 2 times the risk of those who do not have one of these lesions) and include usual ductal hyperplasia (without atypia) and fibroadenoma.73
• Proliferative lesions with atypia are associated with about 4 times higher than average breast cancer risk. These include atypical ductal hyperplasia and atypical lobular hyperplasia.73, 74 Recent studies indicate that the 15-year risk of developing in situ or invasive breast cancer exceeds 30% in women diagnosed with atypical hyperplasia.74, 75
Women should keep detailed records of any benign breast biopsy results because they are valuable for risk assessment, screening, and counseling for chemoprevention and other risk-reduction strategies.
Breast density
Breast tissue density is an indicator of the amount of glandular and connective tissue relative to fatty tissue measured during a mammogram and is not determined by how “firm” the breast feels. Following a mammogram, doctors categorize a woman’s breast tissue according to standardized system developed by the American College of Radiology called the Breast Imagine Reporting and Data System (BI-RADS) as A) fatty; B) scattered areas of fibroglandular tissue; C) heterogeneously dense; and D) extremely dense. Women with breasts classified as C (heterogeneously dense) or D (extremely dense) are referred to as having “dense breasts.” The risk of breast cancer increases with increasing breast density. Women with dense breasts (BI-RADS C or D) have a 1.5- to 2-fold increased risk of breast cancer compared to those with average density (BI-RADS B).76 High breast density can also mask the appearance of breast tumors on a mammogram.77
Dense breasts are common. About 36% of US women ages 40-74 have heterogeneously dense breasts and about 7% have extremely dense breasts (BI-RADS C or D, respectively).78 Breast density is influenced by genetics and other factors. For most women, breast density generally decreases with age, higher body weight, and after pregnancy and menopause.79 Some drugs also affect breast density, including tamoxifen (decreases density) and combined menopausal hormone therapy (increases density).79, 80
In early 2019, the US Food and Drug Administration proposed a federal rule that mammogram reports include information about breast density. Thirty-eight states and the District of Columbia previously passed some form of breast density legislation. Some state laws require that women with dense breasts be told that they may benefit from supplemental imaging tests, such as ultrasound or MRI. However, there is currently no expert consensus about what other tests, if any, should be done in addition to mammograms to screen for breast cancer in women with dense breasts.81 Ongoing clinical trials are evaluating whether digital breast tomosynthesis (DBT) or MRI may be more useful than conventional digital mammography in evaluating dense breasts.82 See page 20 for more information on DBT.
Height
Many studies have found that taller women have a higher risk of breast cancer than shorter women.83-85 A pooled study of more than 5 million women estimated that an increase of 10 cm (about 4 inches) in height was associated with about a 17% higher risk of breast cancer.84 Although the reasons are not fully understood, it may reflect differences in early growth as well as hormonal or genetic factors. Height is also associated with a number of other cancers, including colorectal and ovarian cancers
Menstrual cycles
Breast cancer risk increases with earlier menstruation and later menopause.86 For example, breast cancer risk is about 20% higher among those who begin menstruating before age 11 compared to those who begin at age 14 or older. Likewise, women who experience menopause at age 55 or older have about a 12% higher risk compared to those who do so between ages 50-54.86 The increased risk may be due to longer lifetime exposure to reproductive hormones and has been more strongly linked to HR+ breast cancer than other subtypes.50
Bone mineral density
High bone mineral density in postmenopausal women has been associated with a 60%-80% increased risk for breast cancer compared to low bone density; risk appears to be most strongly related to HR+ disease.87, 88 Bone density is not thought to be an independent risk factor for breast cancer, but a marker of cumulative estrogen exposure.89 However, because bone density is routinely measured to identify women at increased risk for osteoporosis (high bone density indicates absence of osteoporosis); it also may be helpful for identifying women at increased risk for breast cancer.
Endogenous hormone levels
Postmenopausal women with naturally high levels of certain endogenous sex hormones (e.g., estrogen, progesterone) have about twice the risk of developing breast cancer compared to women with the lowest levels, with the strongest relationships found for HR+ tumors.90, 91
High circulating hormone levels are associated with, and may reflect, the effects of other breast cancer risk factors, such as postmenopausal obesity and alcohol use.91 Although it is challenging to study the relationship of hormones in premenopausal women because levels vary across the menstrual cycle, there is some evidence that high levels of circulating estrogens and androgens are associated with a small excess risk in premenopausal women, particularly for HR+ breast cancer.91-93
Reproductive factors
Pregnancy
Pregnancy has a dual effect on breast cancer risk.94 In the short term, women who have had a full-term pregnancy have an increased risk of both HR+ and HRbreast cancers that peaks at 5 years after childbirth. However, after about two decades, the relative risk of HR+ breast cancer becomes slightly lower (by about 20%-25%) in women who have given birth compared to those who have not. Risk is further reduced among women who have their first child at a younger age or have a greater number of children. In contrast, the increased risk for HR- breast cancer persists following a full-term pregnancy.
Fertility drugs
More research is needed on the relationship between breast cancer risk and the long-term effects of ovulationstimulating drugs.95 Most studies to date have found that breast cancer risk is not elevated in women who undergo in vitro fertilization.96-100 However, the data are less clear for clomiphene (Clomid), a drug that is often used as a first-line treatment for infertility.97, 99, 100 A long-term follow-up study of women seen at 5 US fertility clinics found no association with ever use of Clomid or gonadotropins; however, risk of invasive breast cancer was increased among women who underwent more than 12 Clomid treatment cycles compared to women who had never used fertility drugs.100 Another recent study from Norway reported that use of Clomid was linked to a slightly increased risk of breast cancer, but only among women who had given birth.99
Breastfeeding
Most studies suggest that breastfeeding for a year or more slightly reduces a woman’s overall risk of breast cancer, with longer duration associated with greater risk reduction. In a review of 47 studies in 30 countries, the risk of breast cancer was reduced by 4% for every 12 months of breastfeeding.101 The protective effect may be stronger for – or even limited to – triple negative cancers.102-104
Hormonal birth control
Most studies have found that current or recent use of oral contraceptives (combined estrogen and progesterone) is associated with a small (about 20%) relative increase in breast cancer risk, particularly among women who begin use before first pregnancy.105, 106 Risk appears to diminish when women stop use, and after about 10 years, it is similar to those who have never taken oral contraceptives.
Studies of the levonorgestrel-releasing intrauterine device (Mirena) have produced conflicting results, but a large study from Denmark found that use of Mirena also increases breast cancer risk by about 20%.105, 108-110 In contrast, the use of the injectable progestin-only contraceptive depot-medroxyprogesterone acetate (Depo-Provera) does not seem to be linked with breast cancer.105, 111 Overall, it has been estimated that one extra breast cancer is diagnosed for every 7,690 women using hormonal contraception for one year.105 Notably, data are limited and less clear for “ultra lowdose” (20 micrograms) estrogen formulations.1
Postmenopausal hormones
Recent use of menopausal hormones (also referred to as hormone therapy or hormone replacement therapy) with combined estrogen and progestin increases the risk of HR+ breast cancer, with higher risk associated with longer use.50, 69, 112, 113 Risk appears to be greater for women who start hormone therapy soon after the onset of menopause compared to those who begin later.113, 114 Discontinuation of menopausal hormones diminishes but does not eliminate the increase in breast cancer risk.115 Combined hormone therapy also increases breast density.80
Postmenopausal estrogen-only therapy has been associated with uterine problems (including endometrial cancer) and is therefore only given to women who have undergone hysterectomy. The effects of estrogen-only therapy on breast cancer risk is less clear, but they are likely minimal at most. The Women’s Health Initiative randomized trial116 found that women who used estrogen-only therapy for an average of 6 years had a 25% lower risk of developing breast cancer, but several observational studies have found a slight increase in breast cancer risk among estrogen therapy users, particularly among lean women and those who begin therapy soon after menopause.114, 117, 118 Conflicting results may reflect differences between studies in the prevalence of obesity or higher rates of screening in menopausal hormone users in the observational studies.119
Recently reported results after 18 years of follow-up of the Women’s Health Initiative randomized trial found no increased risk of death overall or due to breast cancer associated with use of estrogen plus progestin or estrogen alone.120
Excess body weight, physical inactivity, diet, alcohol, and tobacco
Excess body weight and weight gain
Postmenopausal HR+ breast cancer risk is about 1.5-2 times higher in women who are overweight or obese.121 Even within the normal range of BMI (18.5-24.9), higher levels of body fat are associated with increased risk of breast cancer after menopause.122 This is likely due, in part, to higher estrogen levels because fat tissue is the largest source of estrogen in postmenopausal women, but may also be related to other mechanisms, including the higher levels of insulin among women with excess body weight.122, 123
Weight gain also increases risk of postmenopausal breast cancer.124, 125 A large meta-analysis found that for each 5 kilograms (about 11 pounds) gained during adulthood, risk of postmenopausal breast cancer increases by 11%.125 Notably, the increased risk was only observed among women who did not use menopausal hormones. Weight loss in early adulthood and after menopause is associated with reduced breast cancer risk in some, but not all studies.123, 126 The effects of weight loss are more difficult to examine because it is often not sustained.
In contrast, studies have found that excess body weight protects against premenopausal breast cancer. A large meta-analysis found that among women between 40 and 49 years of age, the risk for developing breast cancer was about 14% lower in overweight women and 26% lower in obese women compared to women who were normal weight.127 The underlying mechanisms for this inverse relationship are not well understood.123
Physical inactivity
Women who get regular physical activity have a 10%-20% lower risk of breast cancer compared to women who are inactive, with greater risk reduction associated with increasing levels of activity.128-131 The protective effect is independent of BMI and may be limited to women who have never used menopausal hormone therapy.131 The benefit may be due to the effects of physical activity on systemic inflammation, hormone levels, and energy balance.131, 132
Diet
Numerous studies have examined the relationship between food consumption (including fat, fiber, soy, dairy, meat, and fruits and vegetables) and breast cancer with mixed results. A recent meta-analysis concluded there was no association between breast cancer and dietary fat consumption.133 It has been suggested that soy consumption may reduce breast cancer risk, in part because of historically low breast cancer rates among Asian women, who have a diet high in soy. A metaanalysis showed that soy intake was inversely associated with breast cancer risk in Asian but not Western populations, perhaps because Asian women generally consume more soy products beginning at an earlier age than Western women.134
There is limited but growing evidence that high levels of fruit and/or vegetable consumption may reduce the risk of HR- breast cancer.135-137 These findings are supported by studies linking lower breast cancer risk to higher blood levels of carotenoids (micronutrients found in fruits and vegetables).138-140 Studies also suggest that calcium-rich diets may be linked to lower risk of breast cancer.136 The effect of diet on breast cancer risk remains an active area of research, with studies particularly focused on the timing of exposure, specific dietary components, and risk differences by tumor hormone receptor status.
Alcohol
Numerous studies have confirmed that alcohol consumption increases the risk of breast cancer in women by about 7%-10% for each 10 grams (roughly one drink) of alcohol consumed per day on average.141 Women who have 2-3 alcoholic drinks per day have a 20% higher risk of breast cancer compared to non-drinkers. There is also some evidence that alcohol consumption before first pregnancy may particularly affect risk.141, 142 Although mechanisms are not well understood, alcohol may increase risk indirectly by increasing estrogen and other hormone levels.143 Alcohol use appears more strongly associated with risk for HR+ than HR- breast cancers.50, 144
Tobacco
Accumulating research indicates that smoking may slightly increase breast cancer risk, particularly longterm, heavy smoking and among women who start smoking before their first pregnancy.145, 146 A review by American Cancer Society researchers found that women who initiated smoking more than 10 years before the birth of their first child had a 18% higher risk of breast cancer than women who never smoked.146 Some studies suggest secondhand smoke may increase risk, particularly when exposure happens in childhood and for premenopausal breast cancer.147-148
Environmental and other risk factors
Radiation
Radiation exposure has been shown to increase breast cancer risk in studies of atomic bomb survivors and females treated with high-dose radiation therapy to the chest between 10 and 30 years of age, such as for Hodgkin lymphoma. This may be because breast tissue is most susceptible to carcinogens before it is fully differentiated, which occurs with first childbirth. Breast cancer risk starts to rise about 8 years after radiation treatment and continues to be elevated for more than 35 years.149 Although radiation treatments have evolved to include lower doses given over smaller areas, recent studies suggest that the elevated breast cancer risk persists.150
Diethylstilbestrol (DES) exposure
From the 1940s through 1971, some pregnant women were given the drug DES because it was thought to lower the risk of miscarriage. These women have an increased risk (about 30%) of developing breast cancer compared to women who have not taken DES.151 It remains unclear whether women born to mothers who took DES also have a higher risk.151-153
Environmental chemicals and pollutants
Many occupational, environmental, and chemical exposures have been proposed as causes of breast cancer. In general, epidemiological studies have not found clear relationships between environmental pollutants, such as organochlorine pesticides, and breast cancer. Studies to date have found no association between increased concentrations of organochlorines (e.g., dichlorodiphenyl trichloroethane, or DDT) in blood and fat tissue of adults and breast cancer risk,154 although a recent study found in utero exposure to DDT was linked to elevated breast cancer risk later in life.155 Animal studies have demonstrated that prolonged, high-dose exposure to many chemicals can increase mammary tumor development, but it is unknown whether the much lower dose exposures that occur in the general environment increase human breast cancer risk. Furthermore, many relevant chemicals have not been adequately studied in humans and this is an active area of research.156-15
Night shift work
Most studies of nurses who work night shifts and flight attendants who experience circadian rhythm disruption caused by crossing multiple time zones have found increased risks of breast cancer associated with longterm employment.159, 160 Elevated risk appears to be most strongly associated with shift working during early adulthood.161, 162 Exposure to light at night disrupts the production of melatonin, a hormone that regulates sleep. Experimental evidence suggests that melatonin may also inhibit the growth of small, established tumors and prevent new tumors from developing.163 Based on the results of studies in humans and animals, the International Agency for Research on Cancer has concluded that shift work, particularly at night, is probably carcinogenic to humans.164
Factors that are not associated with breast cancer risk
Abortion
There are persistent claims that women who have had an abortion are at increased risk for developing breast cancer based on early studies that have since been deemed methodologically flawed by the American College of Obstetricians and Gynecology.165 Indeed, a large body of solid scientific evidence, including a review by a panel of experts convened by the National Cancer Institute in 2003, confirms that there is no link between breast cancer and abortion (either spontaneous or induced).166
Bras
Although internet rumors have suggested that bras cause breast cancer by obstructing lymph flow, there is no scientific basis or evidence to support this claim. A recent population-based study of more than 1,500 women found no association between wearing a bra and breast cancer.167
Breast implants
No association has been found between breast implants and risk of breast cancer; however, there is evidence that women with implants are at increased risk of a rare type of lymphoma.168 In addition, breast implants can obstruct the view of breast tissue during mammography. Women with breast implants should inform the mammography facility about the implants during scheduling so that additional x-ray pictures (called implant displacement views) may be used to allow for more complete breast imaging.
Chemoprevention and prophylactic surgery
Chemoprevention
The use of drugs to reduce the risk of disease is called chemoprevention. Currently, the US Food and Drug Administration has approved two drugs to help lower the risk of breast cancer in high-risk women: tamoxifen and raloxifene (postmenopausal women only). These drugs are classified as selective estrogen receptor modulators (SERMs) because they block estrogen in some tissues of the body, but act like estrogen in others.
A large meta-analysis, including more than 83,000 high-risk women, found that SERMs reduced breast cancer risk by 38% over 10 years.169 Although the benefit is limited to ER+ disease, these drugs lower the risk of both invasive cancer and DCIS. However, SERMs are associated with some side effects, including hot flashes, nausea, and fatigue. Premenopausal women taking tamoxifen can also experience menstrual changes. More serious side effects are rare but include blood clots and endometrial cancer.169
Clinical trials have shown that another class of drugs – aromatase inhibitors – also reduce breast cancer risk (by more than half) among high-risk postmenopausal women.170 As a result, the US Preventive Services Task Force recently expanded their recommendations to include aromatase inhibitors, as well as SERMS, for breast cancer risk reduction in high-risk women.171 Aromatase inhibitors can decrease bone density, so women taking these drugs must be monitored for osteoporosis.
Prophylactic surgery
Women at very high risk of breast cancer (such as those with pathogenic BRCA gene variants) may elect prophylactic (preventive) mastectomy. Removal of both breasts reduces the risk of breast cancer by 90% or more.172 Prophylactic salpingo-oophorectomy (surgical removal of the fallopian tubes and ovaries) reduces the risk of ovarian cancer, but the benefit for breast cancer in high-risk women is less clear and may be limited to BRCA2 mutation carriers.173 Importantly, however, many women who elect prophylactic surgery would not have developed cancer. Women considering these options should discuss the benefits and limitations with their doctor, and a second opinion is strongly recommended. See page 23 for further discussion of contralateral prophylactic mastectomy in women diagnosed with unilateral breast cancer.
Breast Cancer Screening
American Cancer Society recommendations for the early detection of breast cancer vary depending on a woman’s age and include mammography, as well as magnetic resonance imaging (MRI) for women at high risk. The recommendations for average-risk women were most recently updated in 2015 (see box, opposite page);174 recommendations for women at increased risk will be updated in 2020.
Mammography
Mammography is a low-dose x-ray image of breast tissue. Although early mammographic images were on x-ray film, digital technology, in which a 2-dimensional (2D) image of breast tissue is captured electronically and viewed on a monitor, has largely replaced screen-film mammography. Digital mammography has improved sensitivity for women under age 50 and those with dense breast tissue.175
Early detection of breast cancer by mammography reduces the risk of breast cancer death and increases treatment options, including less extensive surgery and/or the use of chemotherapy with fewer side effects, and sometimes, the option to forgo chemotherapy. Combined analysis of breast cancer screening in randomized trials has demonstrated an overall reduction in breast cancer deaths of about 20%.176 More recent results from organized mammography programs in Europe and Canada indicate that the risk of breast cancer death was reduced by more than 40% among women who were screened.177-179
Women should also be informed of the limitations of mammography. Mammography will not detect all breast cancers, and some breast cancers detected by screening still have poor prognosis. Mammography screening may also lead to overdiagnosis. That is, some breast tumors or lesions detected by mammography, particularly DCIS, would not have progressed or otherwise been detected without screening. Estimates of the prevalence of overdiagnosis vary widely because it cannot be directly measured.180 Mammography may also result in falsepositive results, which lead to follow-up examinations, including biopsies, when there is no cancer; false positives are more likely when women have their first screening. About 12% of women screened with modern digital mammography require follow-up imaging or biopsy, but most (95%) of these women do not have cancer.181 Cummulative radiation exposure from repeated mammograms may slightly increase the risk of breast cancer;182 however, the dose of radiation during a mammogram is relatively small and the benefit of screening likely outweighs any harm. Reducing radiation exposure through more effective imaging is an area of current research.
The Affordable Care Act requires that Medicare and all new private health insurance plans fully cover screening mammograms without any out-of-pocket expense for patients. There are also programs, such as the CDC’s National Breast and Cervical Cancer Early Detection Program, that offer mammography services for low-income, uninsured, and underserved women. For help locating a free or low-cost screening mammogram in your area, contact the American Cancer Society at 1-800-227-2345.
Digital breast tomosynthesis (DBT)
In 2011, the FDA approved the use of DBT (also referred to as 3D mammography) for breast cancer screening. DBT takes multiple breast images, in combination with digital 2D mammography, which can be used to construct a 3D image of the breast. Some studies have found that DBT may be more sensitive (i.e., detect more cancers) and have
Prevalence of mammograph
• In 2018, the prevalence of up-to-date mammography according to American Cancer Society recommendations was lower among Hispanic and Asian (55%-60%) women than NH black (66%), NH white, and AIAN (both 64%) women (Table 5).185 However, studies have documented that self-reported survey data overestimate mammography screening prevalence, particularly among black and Hispanic women.34- 36, 186
• Only 30% of uninsured women were up to date with breast cancer screening in 2018, compared to 64% of insured women.
• The prevalence of up-to-date breast cancer screening was 70% or higher among lesbian women, college graduates, and those ages 55-74 years.
• In 2016, by state, the prevalence of up-to-date mammography among women ages 45 and older ranged from 57% in Wyoming to 79% in Rhode Island (Table 6).187
Breast MRI uses high-powered magnets along with radio waves and computers to produce an image. In 2007, the American Cancer Society published recommendations for the use of MRI for screening women at increased risk of breast cancer.188
Beginning at age 30, annual screening with MRI, in addition to mammography, is recommended for women with an estimated lifetime risk of breast cancer of at least 20%-25% due to the presence of a high-risk variation in the breast cancer susceptibility genes BRCA1 or BRCA2, a first-degree relative with a BRCA1 or BRCA2 mutation (if the woman herself has not been tested), a strong family history of breast and/or ovarian cancer, prior chest radiation therapy (e.g., for Hodgkin lymphoma), as well as women with Li-Fraumeni, Cowden, and Bannayan-RileyRuvalcaba syndromes and their first-degree relatives.188
Women with an estimated 15%-20% lifetime risk, including women with dense breast tissue, should talk with their doctors about the benefits and limitations of adding MRI screening to their annual mammogram. MRI screening is not recommended for women whose lifetime risk of breast cancer is less than 15%. Studies indicate that MRI is underutilized among high-risk women and overutilized by women who are not at high risk for breast cancer.189 MRI should supplement not replace mammography and should be done at facilities that are accredited by the American College of Radiology. Although MRI is more expensive than mammography, most major insurance companies will cover some portion of the cost if a woman is demonstrated to be at sufficiently high risk.
Breast ultrasound
Breast ultrasound is sometimes used to evaluate abnormal findings from a mammogram or physical exam. It is completed with a wand-like handheld device that captures images of the breast with sound waves. For women with mammographically dense breast tissue, ultrasound combined with mammography may be more sensitive than mammography alone; however, it also increases the likelihood of false-positive results.190, 191 The use of ultrasound instead of mammograms for breast cancer screening is not recommended.
Clinical breast examination (CBE)
The American Cancer Society no longer recommends CBE for breast cancer screening in average-risk asymptomatic women based on lack of clear benefits for CBE alone or in conjunction with mammography.174 Furthermore, there is some evidence that adding CBE to mammography screening increases the rate of false positives.
Breast self-awareness
Although the American Cancer Society also no longer
recommends that women perform monthly breast
self-exams (BSE), all women should become familiar with
both the appearance and feel of their breasts and report
any changes promptly to their physician. If a lump or
other symptoms develop, women should contact a doctor
immediately, even after a recent normal mammogram.
To be continue
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