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New study: women with the real facts about mammograms are more likely to opt out of the test.
Despite the pink campaign for early breast cancer detection, a recent Canadian study confirms that mammograms don't save lives.
It's true that breast screening campaigns find more cancer. Since they were implemented in the UK, Europe, the U.S., Australia, and other countries, the incidence of breast cancer has increased by 2% to 10% per year.[i] But finding all of those extra cases of breast cancer earlier hasn't saved lives.
The 25-year Canadian National Breast Screening Study followed 89,835 women, aged 40 to 59, in a randomized controlled trial. About half of the women were given annual mammograms and the other half just visited their doctor without receiving the test.
The researchers found that getting an annual mammogram does not reduce the mortality from breast cancer any more than getting a physical exam from a doctor.[ii]
They also found that annual mammograms are not just useless; they can be seriously harmful. The study results showed a significant risk of over-diagnosis and over-treatment.
Over-diagnosis refers to the diagnosis and treatment of breast cancer that would not have presented clinically during a woman's lifetime.
Overall, 22% of the women in the study - or 1 in every 424 women – were subjected to the trauma of a needless breast cancer diagnosis and unnecessary cancer treatments.
The Canadian study confirms the results of an earlier American study published in the New England Journal of Medicine. It found that over a 30-year period more than 1.3 million women have been wrongly treated for breast cancer.
But most women will never hear this information from their doctors. The majority of physicians still recommend an annual mammogram and some are very critical of these studies showing the downside of breast screenings.
What if more women were told about the risks of getting screened for breast cancer? Would they still be as likely to participate in the great early detection scheme?
According to a new study published in The Lancet the answer appears to be NO.[iii] It found that becoming better informed about over-diagnosis meant women were less likely to choose to get a mammogram.
The study involved 879 Australia women aged 48 to 50 years old. They were randomly divided into two groups. One group received a short booklet explaining the expected frequency of over-diagnosis, breast cancer mortality reduction, and false positives. The information included the absolute numbers affected by over-diagnosis per 1000 women screened over 20 years from age 50. The control group received the same information but without the facts on over-diagnosis.
The researchers found that compared to the control group, when women received information about over-diagnosis, significantly fewer of them intended to get a mammogram. Only 74% of women with the additional information intended to get screened compared to 87% of women who weren't told about the risks of over-detection.
The harms caused by an unnecessary diagnosis of breast cancer are tragic. Most women diagnosed with early breast cancer are treated comprehensively for breast cancer, even though some have over-diagnosed (harmless) cancers.
It turns healthy women into patients and subjects them to risky cancer treatments, including surgery, chemotherapy, and radiation. That also opens them up to other diseases.
Other breast cancer therapies cause hot flushes (30% of women), trouble sleeping (20%), weight gain (20%), loss of interest in sex (8-16%), and lack of energy (16-20%).[vi] Not to mention the effect on family members, relationships, financial stress, and insurance status for the over-treated women.[vii]
And getting the test itself is harmful. The radiation used in x-ray-based breast screenings is much more carcinogenic than previously believed. In fact, mammograms may even accelerate the breast cancer epidemic.
The authors noted that better technology is not necessarily good news for women. Since the introduction of digital mammography, cancer detection has significantly increased without reducing mortality rates. Tomosynthesis (three dimensional mammography) promises a 30-50% increase in detection of breast cancers with even more over-diagnosis.
They also called for a moratorium on new breast imaging technologies until incremental benefit to women has been demonstrated.
For more information visit GreenMedInfo's Health Guide: Breast Cancer
[i] Alexandra Barratt "Overdiagnosis in mammography screening: a 45 year journey from shadowy idea to acknowledged reality." BMJ 2015; 350:h867
[ii] Anthony B. Miller et al. "Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial." BMJ 2014;348:g366
[iii] Jolyn Hersch, Alexandra Barratt, Jesse Jansen, Les Irwig, Kevin McGeechan, Gemma Jacklyn, Hazel Thornton, Haryana Dhillon, Nehmat Houssami, Kirsten McCaffery. "Use of a decision aid including information on overdetection to support informed choice about breast cancer screening: a randomised controlled trial." The Lancet, 2015; DOI: 10.1016/S0140-6736(15)60123-4
[iv] Darby SC, Ewertz M, McGale P, Bennet AM, Blom-Goldman U, Brønnum D, et al. "Risk of ischemic heart disease in women after radiotherapy for breast cancer." N Engl J Med 2013;368:987-98.
[v] Clarke M, Collins R, Darby S, Davies C, Elphinstone P, Evans E, et al. Effects of radiotherapy and of differences in the extent of surgery for early breast cancer on local recurrence and 15-year survival: an overview of the randomised trials. Lancet 2005;366:2087-106.
[vi] Fallowfield L, Cella D, Cuzick J, Francis S, Locker G, Howell A. Quality of life of postmenopausal women in the arimidex, tamoxifen, alone or in combination (ATAC) adjuvant breast cancer trial. J Clin Oncol 2004;22:4261-71.
[vii] Ganz PA. Psychological and social aspects of breast cancer. Oncology (Williston Park) 2008;22:642-50.