April 4, 2012
For Every Woman Claimed Saved By Mammograms, Ten Suffer Unnecessary Treatment
Mammograms have always caused more cancer than they prevent. More evidence is coming forward to support the dangerous and outdated practice of breast screening. Thousands of women are undergoing unnecessary treatment for breast cancer including chemotherapy and even breast removal following screening, researchers have found.
Of women who get yearly mammograms, 61 percent will have at least one false-positive result over a decade.
Previous research from Sweden showed that of 60,000 women, 70 percent of the mammographically detected tumors weren't tumors at all. These "false positives" aren't just financial and emotional strains, they may also lead to many unnecessary and invasive biopsies. In fact, 70 to 80 percent of all positive mammograms do not, upon biopsy, show any presence of cancer.
At the same time, mammograms also have a high rate of missed tumors, or "false negatives." Dr. Samuel S. Epstein, in his book, The Politics Of Cancer, claims that in women ages 40 to 49, one in four instances of cancer is missed at each mammography. The National Cancer Institute (NCI) puts the false negative rate even higher at 40 percent among women ages 40-49. National Institutes of Health spokespeople also admit that mammograms miss 10 percent of malignant tumors in women over 50. Researchers have found that breast tissue is denser among younger women, making it difficult to detect tumors. For this reason, false negatives are twice as likely to occur in premenopausal mammograms.
In the latest research, academics from Harvard School of Public Health studied the results from 40,000 women who were screened in Norway.
They found for every 2,500 women offered screening, one death from breast cancer would be prevented - but six to 10 women would be treated for a benign cancer that would never cause symptoms.
This 'overdiagnosis' results in thousands of women receiving damaging treatment including surgery, powerful drugs like tamoxifen and chemotherapy. If the cancer appears aggressive the decision may be made to remove the whole breast - a procedure known as a mastectomy.
The Harvard study is the latest in a recent slew of research to question the long-held belief that the benefits of national screening programmes far outweigh the harm they can cause.
In the UK, the NHS screens around 1.6million women for breast cancer every year. Women aged from 47 to 73 are invited to screening every three years as the risk of developing the condition increases with age.
Breast cancer deaths have fallen by more than 10 per cent in Britain over the past five years, which Stephen Duffy from Cancer Research UK said was partly due to screening.
However, a recent study from the International Prevention Research Institute in Lyon, France, suggested better treatments are more likely to be causing the recent drop in death rates.
There is currently an independent review underway into whether the UK programme causes more benefit than harm.
A Department of Health spokesman said: 'Our screening programme is regularly scrutinised.
'We know that there are some scientists who differ in their views towards screening, so as requested by ministers, the National Cancer Director Professor Sir Mike Richards has commissioned an independent review of the evidence in partnership with Harpal Kumar, chief executive of Cancer Research UK.'
In the latest study the Harvard researchers estimate that up to a quarter of breast cancers found by mammograms won't cause any problems during a woman's lifetime.
Once cancer is found, however, doctors must treat it as they do not yet have an effective technique of working out which ones will be dangerous.
'When you look for cancer early and you look really hard, you find forms that are ultimately never going to bother the patient,' said Dr H. Gilbert Welch of the Dartmouth Institute for Health Policy and Clinical Practice, who was not part of the research.
'It's a side effect of early diagnosis.'
The study from Harvard School of Public Health is the latest to explore overdiagnosis from routine mammograms - finding tumors that grow so slowly or not at all and that would not have caused symptoms or death. Previous estimates of the problem have varied.
The researchers took advantage of the staggered decade-long introduction of a screening program in Norway, starting in 1996. That allowed them to compare the number of breast cancers in counties where screening was offered with those in areas that didn't yet have the program. Their analysis also included a decade before mammograms were offered.
Study leader Dr. Mette Kalager and other experts said women need to be better informed about the possibility that mammograms can pick up cancers that will never be life-threatening when they consider getting screened.
'Once you've decided to undergo mammography screening, you also have to deal with the consequences that you might be overdiagnosed,' said Kalager, a breast surgeon at Norway's Telemark Hospital and a visiting scientist at Harvard School of Public Health.
'By then, I think, it's too late. You have to get treated.'
Kalager and her colleagues looked only at invasive breast cancer. The study did not include DCIS, or ductal carcinoma in situ - an earlier stage cancer confined to a milk duct.
Under the Norway program, screening was offered every two years to women ages 50 to 69.
Researchers analysed nearly 40,000 breast cancer cases, including 7,793 that were detected after routine screening began. They estimated that between 1,169 and 1,948 of those women were overdiagnosed and got treatment they didn't need.
Their findings appear in Tuesday's Annals of Internal Medicine.
Commenting on the study Dr Welch said: 'The truth is that we've exaggerated the benefits of screening and we've ignored the harms.
'I think we're headed to a place where we realize we need to give women a more balanced message: Mammography helps some people but it leads others to be treated unnecessarily.'
An editorial published with the study said overdiagnosis probably occurs more often in the United States because American women often start annual screening at an earlier age and radiologists in the U.S. are more likely to report suspicious findings than those in Europe.
'It's not the great lifesaver that people think it is. It's not a magic bullet,' said Dr Jeanne Mandelblatt of Georgetown University, who is shaping new mammogram guidelines for a U.S government task force.
If mammograms are both useless and dangerous, why then does the medical community continue to use it and other "heroic" cancer practices? The answer as to why they behave so caustically toward patients has been given many times in the history of medicine with the only difference now being that they have legally suppressed a citizen's right to choice in health care.
Radiologists could help by raising the threshold for noting abnormalities, wrote Dr Joann Elmore of the University of Washington School of Medicine and Dr. Suzanne Fletcher of Harvard Medical School.
A 'watch-and-wait' approach has been suggested instead of an immediate biopsy, but the editorial writers acknowledge that could be a 'tough sell' for some women and radiologists alike.
They said most women aren't aware of the possibility of overdiagnosis.
'We have an ethical responsibility to alert women to this phenomenon,' they wrote.
Before you decide to have a mammogram make sure you have been told of the risks in advance. Get the facts (the truth is out there) and then make your own conclusions.