Do annual mammograms save lives?
Several studies over the past few years have concluded that mammograms do not save lives, and may actually harm more women than they help, courtesy of false positives, overtreatment, and radiation-induced cancers.
According to research published in 2010, the reduction in mortality as a result of mammographic screening was so small as to be nonexistent — a mere 2.4 deaths per 100,000 person-years were spared.
Another study published in The Lancet Oncology in 2011 demonstrated, for the first time, that women who received the most breast screenings had a highercumulative incidence of invasive breast cancer over the following six years than the control group who received far less screenings.
Now, researchers from Harvard and Dartmouth have published a paper in which they present similar conclusions.
Mammograms Have No Impact on Breast Cancer Mortality
After analyzing cancer registry data from 16 million women in 547 counties across the United States, they found “no evident correlation between the extent of screening and 10-year breast cancer mortality.”
The researchers concluded that mammograms primarily find small, typically harmless, or non-lethal tumors, leading to widespread overdiagnosis.
As explained by Dr. Otis Webb Brawley, chief medical officer of the American Cancer Society and author of the book, How We Do Harm, the term “overdiagnosis” in cancer medicine refers to:
“…a tumor that fulfills all laboratory criteria to be called cancer but, if left alone, would never cause harm. This is a tumor that will not continue to grow, spread, and kill. It is a tumor that can be cured with treatment but does not need to be treated and/or cured.”
“For every 10-percentage-point increase in screening rates, the incidence of breast cancer rose by 16 percent… That worked out to an extra 35 to 49 breast cancer cases for every 100,000 women…
The researchers also examined breast cancers according to their stage at diagnosis, a marker of a tumor’s aggressiveness. More screening was associated with a higher incidence of early-stage breast cancers but no change for later-stage tumors, according to the study.
How can this be?
‘The simplest explanation is widespread overdiagnosis, which increases the incidence of small cancers without changing mortality,’ the study authors wrote. ‘Even where there are 1.8 times as many cancers being diagnosed, mortality is the same.’”
To Screen or Not to Screen?
Clearly, the issue of breast cancer screening using mammography can be a deeply emotional one. Virtually all discussions relating to cancer are. A recent article in Forbes Magazine paints a vivid picture of most women’s fears, and warns of the dangers of not getting diagnosed in time.
While it needs to be an individual choice, I believe it can be valuable to take a step back and look at the big picture, which includes population-based statistics such as those presented above.
“[The] study authors… point to a balance of benefits and harms and believe mammography is likely most favorable when directed at women who are at high risk — not too rarely and not too frequently.
They also believe watchful waiting, rather than immediate active treatment, is probably a good option in some cases.”
A main objection to mammography is the fact that it uses ionizing radiation to take images of your breasts, and it’s a well-established fact that ionizing radiation can cause cancer.
So the idea that the “best” way for you to avoid dying from cancer is to expose yourself to cancer-promoting radiation at regular intervals for decades on end (in order to catch the cancer early) really falls short on logic — especially since there are non-ionizing radiation imaging techniques available.
Results published in the British Medical Journal (BMJ) in 2012 show that women carrying a specific gene mutation called BRCA1/2 are particularly vulnerable to radiation-induced cancer.
Women carrying this mutation who were exposed to diagnostic radiation before the age of 30 were twice as likely to develop breast cancer, compared to those who did not have the mutated gene.
They also found that the radiation-induced cancer was dose-responsive, meaning the greater the dose, the higher the risk of cancer developing. The authors concluded that:
“The results of this study support the use of non-ionizing radiation imaging techniques (such as magnetic resonance imaging) as the main tool for surveillance in young women with BRCA1/2 mutations.”
Mammograms Do Not Reduce Mortality Beyond That of Physical Examination
It involved 90,000 women who were followed for 25 years, and it sent shockwaves through the medical industry when it reported that the death rates from breast cancer were virtually identical among women who got annual mammograms and those who did not.
“One in five cancers found with mammography and treated was not a threat to the woman’s health and did not need treatment such as chemotherapy, surgery, or radiation.”
At the outset of the study, the women, aged 40-59, were randomly assigned to receive either five annual mammography screens, or an annual physical breast examination without mammography.Over the course of the study, 3,250 of the women who received mammography were diagnosed with breast cancer, compared to 3,133 in the non-mammography group.
Of those, 500 women in the mammography group, and 505 in the control group, died from the disease. However, after 15 years of follow-up, the mammography group had another 106 extra cancer diagnoses, which were attributed to overdiagnosis. According to the authors:
“Annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available. Overall, 22 percent of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial.”
The rate of overdiagnosis (22 percent) is virtually identical to that found in a 2012 Norwegian study, which found that as many as 25 percent of women are consistently overdiagnosed with breast cancer that, if left alone, would cause no harm. Other studies that have come to similar conclusions include the following:
- In 2007, the Archives of Internal Medicine12 published a meta-analysis of 117 randomized, controlled mammogram trials. Among its findings: rates of false-positive results are high (20-56 percent after 10 mammograms)
- A 2009 meta analysis by the Cochrane Database review13 found that breast cancer screening led to a 30 percent rate of overdiagnosis and overtreatment, which increasedthe absolute risk of developing cancer by 0.5 percent. The review concluded that for every 2,000 women invited for screening throughout a 10 year period, the life of just ONE woman was prolonged, while 10 healthy women were underwent unnecessary treatment.
Know the Signs and Symptoms of Breast Cancer
Mammograms can also miss the presence of cancer. According to the National Cancer Institute (NCI), mammograms miss up to 20 percent of breast cancers present at the time of screening. Your risk for a false negative is particularly great if you have dense breast tissue, and an estimated 49 percent of women do. Mammography’s sensitivity for dense breasts is as low as 27 percent, which means that about 75 percent of dense-breasted women are at risk for a cancer being missed if they rely solely on mammography. Even with digital mammography, the sensitivity is still less than 60 percent.
Considering the mortality rate from breast cancer is virtually identical whether you get an annual mammogram or an annual physical breast exam, it suggests physical examination can go a long way toward detecting a potential cancer. It certainly makes sense to familiarize yourself with your breasts and the signs and symptoms of breast cancer. If you notice any of the following symptoms, be sure to address it with your doctor, even if you’re not due for an annual checkup yet.
- Lump in the breast (keep in mind that breast lumps are common, and most are not cancerous)
- Pain or unusual tenderness or swelling in the breast
- Retracted nipple
- Nipple discharge
- Vaginal pain
- Dimpling of the breast surface, and/or “orange peel” skin texture
- Visible veins on the breast
- Enlarged lymph nodes (located in the armpit)
- Unintentional weight loss
To learn about Breast Cancer prevention tips, and to read Dr. Mercola’s full article click here.