Traditionally, mammograms were considered the best way to find breast cancer on an early stage, when it is easier to treat. However, lately, the numerous scientific studies question the standard approach and its application framework, calling for urgent guidelines revision.
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.
New American Study
The new scientific findings recommend doctors to focus on life expectancy when deciding whether to recommend mammograms for their older female patients, since the harms of screening most likely to outweigh the benefits unless women are expected to live at least another decade, according to a review of the scientific literature by experts at UCSF and Harvard medical schools.
Accepted national guidelines recommend that doctors make individualized screening recommendations for all women, including the most adult group of 75 and older. But the recent investigation concluded that since this age group has never been included in any mammography trials before, there is yet to find conclusive evidence that anti breast cancer screening may help them to live longer and healthier lives.
The researchers concluded that many women in this age group receive regular mammograms anyway, with no discussion about the uncertain benefit or potential harms of continued testing, which include unnecessary treatment for slow-growing cancers or pre-cancerous lesions that pose no real threat to the women's lives.
They validated that women who are expected to live a decade or more should talk with their doctors and weigh the potential benefits of diagnosing a dangerous but treatable cancer through mammography against the possibility of being misdiagnosed or treated aggressively for a cancer that posed no real harm.
"People should be informed that everything we do in medicine can have good and bad effects, and that goes for mammography," said Louise Walter, MD, UCSF professor of medicine and chief of the Division of Geriatrics.
The study authors arrived at their unconventional conclusions after examining all the studies conducted from 1990 to 2014 that identified risk factors for late-life breast cancer in women 65 and older, as well as the studies that assessed the value of mammography for women 75 and older.
Since there were no randomized trials of the benefits of screening women over 74, they could not say whether mammography was beneficial for those women. Longitudinal studies found that healthy older women who were screened with mammography were less likely to die from breast cancer, but screening was not beneficial for women with serious medical problems.
Modeling studies indicate mammograms would prevent two cancer deaths for every 1,000 women in their 70s who were screened every two years for 10 years. However, these studies also predicted that about 200 of those women would receive test results indicating they had cancer when they did not, and about 13 would be treated for cancers that posed no harm.
Doctors use complex algorithms to assess breast cancer risk, but these calculations lose their ability to predict disease in the oldest women, because risk factors change as women age.
For example, how old a woman was when she first got her period and whether she bore children and at what age are important factors in determining breast cancer risk for women under 75. But these factors are no longer relevant once women reach the age of 75. Instead, the main risk factor for developing breast cancer is age itself.
"The things that may be predictive in older women likely have to do with recent hormone exposure, such as lifelong obesity, high bone density or taking hormones, which are associated with higher estrogen levels," said Mara Schonberg, MD, MPH, an assistant professor of medicine at Harvard Medical School. "Distant hormone exposures, such as the age a woman first got her period, may not make much difference in who gets breast cancer in this older population. Older age is the greatest risk factor for breast cancer."
New Canadian Study
Canadian researchers looked at data from the Canadian National Breast Screening Study, which recruited 89,835 women who were 40-59 at the beginning of the study, gave each of them a clinical breast exam, then assigned each participant to one of two groups: a group that would receive annual mammograms and clinical breast exams for the next four years, or a group that would receive only annual clinical breast exams for the next four years (or, in the case of the women 40-49, would just remain under the care of their regular doctors). Researchers then continued to follow up with the participants until 25 years after their original recruitment.
During the initial screening period, a total of 1,190 breast cancers were diagnosed (666 in the mammography group, and 524 in the control group). The tumors detected by mammograms did tend to be slightly smaller and were a little less likely to be node positive (meaning they had cancerous cells in them). But the mortality rate didn’t differ much between the two groups: During the 25-year follow-up period, 180 women in the mammogram group died, compared to 171 women in the control group.
If you look at the entire study period, 3,250 women in the mammogram group and 3,133 in the control group were diagnosed with breast cancer. The number who died were, again, virtually identical: 500 women in the mammogram group, compared to 505 in the control group.
What’s more, the study authors are asserting that about one in five of the breast cancer diagnoses made as a result of mammograms were over-diagnoses. In other words, had these tumors not been detected, researchers say they never would have caused health issues or required treatment.
“Early detection could be of greater benefit in communities where most cancers that present clinically are larger and a higher proportion are node positive,” write the researchers. “However, in technically advanced countries, our results support the views of some commentators that the rationale for screening by mammography should be urgently reassessed by policy makers.”
While the mammography effectiveness is under heavy debates, performing your breasts self-examination may be quite benefiting and comforting. The better you know your body, the more likely you may notice if something is out-of-the-ordinary and potentially dangerous.
Take charge of your health and learn how to do a breast self-exam by watching this video.
Dr. Schwartz, M.D., a leading advocate of disease prevention and wellness for women, confirms that self-examinations are the best way for women to check for signs of breast cancer.
"We must assume responsibility for our every-day care," she said. "Women should learn to know and love their breasts and perform self-examination on a regular basis. They should follow an anti-inflammatory diet, exercise, and take bio-identical hormones to reduce the risk of cancer."
If a woman does find a suspicious lump in her breast, Dr. Schwartz would then suggest testing for cancer, preferably in the form of an ultrasound, which has less radiation.
Review Risk Factors
When discussing with your doctor whether and how often to have mammograms, take into account your breast cancer risks, which include:
1. Your age. Most aggressive breast cancers are found in women 55 or older.
2. Your genes. Up to 10 percent of breast cancers are inherited, most commonly from mutations in the BRCA1 and BRCA2 genes.
3. Your family history. Having a mother, sister, or daughter with breast cancer increases your risk.
4. Your cancer history. If you've had cancer in one breast, you're three to four times more likely to develop it again in the same or the other breast.
5. Your breast density. Women with denser breasts are more likely to get breast cancer, and their cancer may be harder to spot on a mammogram.
6. Your use of hormone therapy. Taking combined hormone therapy after menopause increases breast cancer risk.
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