If you just want a brief summary of guidelines, look here. For all the details, read on!
Breast Cancer Screening
Over recent years, there have been significant changes in recommendations for how to screen for breast cancer, how often, what age to start at, and what age to stop screening. A significant influence on the debate has been the recommendations issued by the United States Preventive Services Task Force (USPSTF) in 2009, which are summarized in the chart below. (Read the full document here. Our Bodies Ourselves has a helpful detailed examination of them here.)
Here is a review of current thoughts.
Methods of screening:
- Breast self-exam (BSE) – Looking in the mirror for changes, then using a standardized pattern to methodically check the breast for lumps or other changes. (Instructions here.) Past recommendations were for monthly BSE, but research hasn’t shown much benefit to this routine, so it is no longer specifically recommended. Instead, they recommend breast self-awareness – this simply means being familiar with your breasts, and having a sense of what is normal for you so you can tell if there are any changes.
- Clinical breast exam (CBE) – A health care professional examines your breasts, first looking at them for any abnormalities in size or shape, then using hands to feel the breasts, checking for lumps. CDC says it does not reduce the risk of dying from breast cancer
- Mammograms – An x-ray of the breast. See details here. 70% of women over 40 have mammograms. (NY Times, 2013) It is the most effective method for finding breast cancer (though it has limitations as discussed below) and is recommended for all women, although recommendations range on frequency and on age to begin screening (See below)
- Magnetic Resonance Imaging (MRI) – magnets and radio waves create detailed, cross-sectional image of the breast. Details here. It is recommended only for high risk women, and only in conjunction with mammograms. (See below.)
Incidence of Breast Cancer
About 230,000 women are diagnosed with breast cancer each year in the United States. That’s 14% of all cancer diagnoses. The chance that a woman will have breast cancer at some point in her life is around 12%, or 1 in 8 chance. Approximately 90% of breast cancer patients survive at least 5 years beyond diagnosis. (SEER)
The risk of breast increases with age. For a 30 year old, the chance she’ll have it in the next ten years is just .44% (1 in 227). For a 70 year old, the chance is 3.82% (1 in 26.) (National Cancer Institute)
Benefits of breast cancer screening:
Breast self-awareness and CBE may detect some tumors. Mammograms can find malignant tumors that could not be detected by hand. Screening can help to detect breast cancers when they are small and more treatable, and before they spread to other parts of the body. A small tumor is easier to remove and less likely to result in mastectomy. Dr. Richard C. Wender, chief of cancer control for the American Cancer Society says mammography reduces the death rate by at least 15% for women in their 40s and at least 20% for older women.
Another way of viewing this is: For an individual woman in her 40s, the chance of dying of breast cancer in the next ten years is .35% if she doesn’t have annual mammograms and .3% if she does. For a woman in her 50s, annual mammograms lower her risk from .53% to .46%. (NY Times, 2013)
For some women, regular screenings can also reduce their anxiety about developing breast cancer. Everywhere women go, they see pink ribbons, and messages that build their fear of breast cancer and reassure them that “mammograms save lives.” So, the annual checkup soothes their fears. (Interestingly, women may be overly fearful of breast cancer. The actual risk of having breast cancer in your lifetime is 12 – 13%. 89% of women overestimate that, with an average estimate of 46%. Science Daily.)
Hazards of breast cancer screening:
- False negatives: Mammograms may miss 20% of tumors (National Cancer Institute). False negatives are more common for younger women, because mammograms are less effective on younger women’s breasts, which have denser tissue. Digital mammograms may be more effective for women under 50.
- False positives: the mammogram may find something that after further testing turns out to not be cancer. False positives are more common for younger women, women with a family history of breast cancer, and women who are taking estrogen.
- Additional testing and procedures: 10% of mammograms lead to follow-up testing. 8 – 10% of those women will get biopsies. (org) “Research has shown that as many as 75% of post-mammogram biopsy results turn out to be benign (non-cancerous) lesions.” (OBOS) In addition to the risks and costs of these biopsies, they put a huge emotional strain on the women involved as they go through a great deal of fear and anxiety through the testing, biopsy, and waiting for results.
- Over-diagnosis / Over-treatment: Screenings may find DCIS (ductal carcinoma in situ – a non-invasive tumor, which can evolve into cancer) or slow-growing cancers that would never have caused symptoms or threatened the woman’s life. If these are treated, then the woman may be unnecessarily exposed to the side effects of cancer treatment.
- A recent Canadian study found 22% of the breast cancers detected by screening were over-diagnosed. “Put simply, this means that one in five cancers do not pose a deadly threat, yet these women may still undergo treatment, including surgery, chemotherapy and radiation.” (OBOS)
- A review concluded that “for every 2,000 women screened annually over 10 years, one life is prolonged but 10 healthy women are given diagnoses of breast cancer and unnecessarily treated, with therapies that themselves have life-threatening side effects.” (NY Times, 2013)
- Cost: Although most private insurances and Medicare cover the majority of costs of mammogram, and thus individual consumers don’t pay much, the cost to society is high. About 38 million mammograms were performed in the US last year. (FDA) Average cost of a mammogram is $266. (Source.)
Benefit-Risk Ratio depends on the Age and Risk Status of the Individual Woman
The chance of getting breast cancer increases as we get older. The median age of diagnosis is 61. The median age of death is 68. So, screening in your 60s is much more likely to be worth doing (i.e. more likely to find a cancer that will benefit from treatment) than screening at a younger age. The chance of a 20 year woman getting breast cancer in the next ten years is only about .06%. (NY Times, 2013) So, screening is your 20s is not worth doing. (Even talking about breast cancer and breast self-exams with teenagers may just create fear and anxiety without giving benefit.)
What’s the tipping point for starting screening where benefits of screening outweigh the risks? And, what’s talked about less: at what age is it no longer relevant to screen for breast cancer? Let’s start with the recommendations for older women and work down.
Over 75 years of age: Screening may detect breast cancer. But the breast cancers women tend to get at this age are slow-growing. The older woman is more likely to die of other conditions before breast cancer would kill her. Treating a cancer at this age would cause risks and complications and not significantly lengthen life span. USPSTF
Age 50 – 75: There is general consensus that the benefits of screening outweigh the concerns.
Under 50: This is where the controversy lies.
For women who do have breast cancer, mammography increases the chance that will be found early and treated. The USPSTF says screening this age group led to a 15 percent decrease in mortality. The chairman of the USPSTF says: “If I take 1000 women over age 40, over their lifetimes, 30 will die from breast cancer if we do no screening. If I screen every one of those women beginning at age 50 until she’s 74, we reduce the deaths from 30 to 23.” He says if we start the screening in their forties, we might increase that by one additional life saved. (i.e. 22 would die)
However, the rate of false positives and over-treatment are higher for younger women. “Starting mammograms at 40 would mean having exams every two years for an average of 34 years. Over a lifetime, a woman’s chances of needing a biopsy to prove she didn’t have breast cancer might be as high as 50 percent.” (OBOS)
“The Cancer Society says for every 1,000 women in their 40s screened for 10 years, 600 will be called back for a repeat mammogram for something suspicious, 350 will get biopsied and about five will end up with a diagnosis of breast cancer. And some women might get treated for a cancer that would never have caused a problem.” http://www.npr.org/templates/story/story.php?storyId=130437187
Most experts say that between 40 and 50, the decision whether or not to screen is best made through a shared decision-making process between a woman and her physician / caregiver where they evaluate her risk factors, discuss the benefits and risks of screening, and assess her personal feelings about the screening – would it reduce her anxiety or increase it? For women at higher risk of breast cancer (see below), caregivers are more likely to recommend screening in their 40s (or, rarely, even younger than 40) versus they may recommend waiting until your 50s if you are at low risk.
Here is my comparison of major recommendations, from: The Susan Komen Foundation, American Cancer Society (ACS), American Congress of Obstetricians and Gynecologists (ACOG), and the United States Preventive Services Task Force (USPSTF).
* Breast Self Awareness and BSE: What to Look For
Women should be familiar with their breasts and, on occasion, check their appearance in a mirror and/o touch them to see if there are any unexplained changes. Women should remember that breast changes occur with pregnancy, breastfeeding, aging, menopause, during menstrual cycles, and when taking birth control pills or other hormones. It is normal for breasts to feel a little lumpy.
The Komen Foundation and American Cancer Society recommend that if you see these changes, check with your care provider:
- Development of a lump – a thick hard knot inside the breast or under the arm
- Swelling, warmth, redness, or skin irritation
- Change in the size or shape of the breast; nipple pulling inward
- Dimpling or puckering of the skin
- Nipple discharge (other than breastmilk) that starts suddenly
** Risk Assessment
MRI recommendations say that it should be done in addition to mammogram, not instead of, and should be done only for women at high risk: those whose lifetime risk of breast cancer is 20 – 25% or higher.
Here are some guidelines from ACS and Komen Society on what factors would be assessed to determine high risk: A known BRCA1 or BRCA2 gene mutation or a first degree relative with one. Strong family history of breast cancer at age 45 or younger. A personal history of invasive breast cancer, DCIS, LCIS, or atypical hyperplasia. Radiation therapy to the chest between 10 and 30 years of age, Li-Fraumeni, Cowden, or Bannayan-Riley-Ruvalcaba syndromes.
How have benefits, risks, and survival rates changed over the years?
It is difficult to compare studies of how women have fared over the past 25 years with how they will fare over the next 25 years. Here are some factors that have changed breast cancer survival rates:
- Awareness: Decades ago, breast cancer was not often spoken of. Women might have had lumps or other breast changes that they did not report to a physician until too late. As our society has talked about it more and more, it has raised awareness of the issue, which makes it more likely that women with concerning changes will seek treatment sooner.
- Incidence: Increased screening has increased the number of cancers found. (i.e. the percentage of women who will receive a breast cancer diagnosis in their lifetime)
- Understanding of breast cancer: We used to believe that most or all breast cancer was aggressive and would spread throughout the body if not detected and treated early. We now know there are several types of cancer found in the breast (NY Times, 2013), some of which are very slow growing or non-invasive, and some will disappear on their own. (NY Times, 2014) Thus, some of those extra diagnoses mentioned in the previous bullet point are likely to be of cancers that would never have developed into anything clinically significant.
- Treatment has improved: There has been a 25% reduction in deaths since 1990, but it’s likely that is due to treatment, not to detection. (NY Times, 2013), Reductions in mortality are “more likely explained by changes in risk factors and improved treatment than by screening mammography.” BMJ.
Fear of Cancer, and the Politics and Economics of Breast Cancer Screening
Beyond the medical research and current guidelines, there are interesting cultural issues related to this topic which affect recommendations and affect whether women follow those recommendations.
What was the political response to the USPSTF guidelines?
“Rather than engaging in discussion about how to maximize the benefits of screening while minimizing its harms, Republicans seized on the panel’s recommendations as an attempt at health care rationing. The Obama administration was accused of indifference to the lives of America’s mothers, daughters, sisters and wives. Secretary Kathleen Sebelius of the Department of Health and Human Services immediately backpedaled, issuing a statement that the administration’s policies on screening “remain unchanged.” (NY Times, 2013)
How Do Women Feel about Screening Starting at Age 40?
After the USPSTF released their recommendations in 2009, a USA Today survey found that 76% of women disagreed with the recommendations. 84% of women age 35 – 49 said they would get a mammogram before age 50. 76% of women believed the panel recommended fewer mammograms because of cost, even though the panel only looked at medical benefits and risks.
The survey also showed again that women overestimate their risk of breast cancer. Whereas a 40-year-old woman’s chance of getting breast cancer in the next decade is only 1.4%, 40% of women think the chance is 20 – 50%.
Of women who have been diagnosed with cancer in one breast, there has been a significant increase in those opting for a double mastectomy. One study says they chose this to prevent having to face a second cancer (98%) and to improve chance of survival (94%). Even among women diagnosed with DCIS (a risk factor for cancer), there was a 188% increase from 1998 – 2005 in women choosing double mastectomy.
For women with a genetic predisposition to cancer, removing both breasts does not necessarily improve survival rates, and they were generally aware of that when making the decision.
For women who do not have a genetic predisposition, the chance of a cancer in the other breast is only 2 – 4 %, but those women tended to believe that the chance was 10%. In another study they estimated it at 30%. So, they may be basing their decision to have a double mastectomy on a fear-based over-estimation of the risk.
(Data combined from these sources: http://www.oncologynurseadvisor.com/young-women-overestimate-cancer-risk-in-second-breast/article/315231/ and NY Times 2013.)
Breast Cancer Charities may benefit from fears of breast cancer
A Susan Komen Foundation ad campaign from 2011 said “The 5-year survival rate for breast cancer when caught early is 98 percent. When it’s not? 23 percent.” Dr. Steven Woloshin from Dartmouth says this implies “[mammography] has this huge effect, and you’d have to be really irresponsible or crazy to not be screened.” (Huffington Post) But, Woloshin says the statistics are deceptive: “a woman in her 50s who goes for regular mammograms for 10 years will only cut her chance of dying by a fraction of a percentage point — for every 10,000 women who are screened 7 deaths will be prevented.” (MedicineNet)
Gayle Sulik, a sociologist, credits Komen (and other charities) for raising awareness of the disease, transforming “victims” into “survivors” and distributing over $1 billion to research and support. But she says “the function of pink-ribbon culture — and Komen in particular — has become less about eradication of breast cancer than self-perpetuation: maintaining the visibility of the disease and keeping the funds rolling in.” The Komen Foundation does have some vested interest in keeping awareness of breast cancer high. (NY Times, 2013) In 2012, CNBC reported that Komen’s annual income was around $340 million, and that Komen’s founder and CEO received an annual salary of $684,000, which is about a quarter million dollars higher than what is typical for a charity of that size.
Does anyone else have a vested interest in annual mammograms?
“[An] editorial in BMJ, “Too Much Mammography notes that it is difficult to make changes around screening mammography practices “because governments, research funders, scientists, and medical practitioners may have vested interests in continuing activities that are well established.” (OBOS) For example, the American College of Radiology, a trade organization for professionals who conduct and interpret mammograms, objected to recommendations to do mammograms less frequently.
Reducing your Risk of Breast Cancer
Obviously, no matter what screening approach you choose, we’re all hoping the results come back negative! What are some things you can do to increase that chance?
- The more months of total breastfeeding in your life, the lower your risk.
- Limit alcohol. No more than one drink a day.
- Control your weight. Obesity, especially after menopause, increases your risk.
- Don’t smoke. Smoking especially increases the risk of premenopausal breast cancer.
- Limit hormone therapy for menopause related concerns. If you use, try the lowest possible dose that relieves your symptoms, keep use short-term (less than 3 years).
- Minimize exposure to radiation and environmental toxins.
- Exercise regularly.