You can see this clearly in the chart below: The number of diagnosed breast cancers rose with more screening, yet the number of deaths from breast cancer 10 years later remained stubbornly stable. In other words, the screening tests didn’t also lower the deaths.
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This latest study may make many doctors shake head in disbelief since there’s an entire culture of getting as many mammograms as one could to stay away from breast cancer. Scientists published their findings in a recent issue of JAMA Internal Medicine.
Instead, investigators of a survey realized that mammary showing occurs to overdiagnosis of “small, idle or regressive lumps”.
Richard Wilson, D.Phil., of Harvard University, Cambridge, Mass., and coauthors conducted an ecological study of 16 million women ages 40 and older who lived in 547 counties reporting to Surveillance, Epidemiology and End Results cancer registries during the year 2000.
“For small tumors, the mortality benefit often doesn’t emerge until you’re 15 or even 20 years out”, he explained. There was no relationship between screening and advanced-stage cancer, which was troubling to numerous researchers who saw the lack of decrease in mortality rates. Researchers concluded that because there were no fewer large-size cancers found, and the death rate was not reduced, “these findings suggest widespread overdiagnosis”. So, the over-diagnosis epidemic was associated with an additional 36 to 50 new cases per 100,000 women.
There are a lot of uncertainties in these numbers, because the studies that the evaluation looked at are all very different, and because factors such as the use of mammograms at private clinics and hormone treatment during menopause are things that most studies have not been able to consider.
The team found that in areas where mammograms were used more, the number of women who were told they had cancer increased. Except for skin cancer, breast cancer is the most common cancer in American women.
Researchers at the University of Leeds and the Institute of Cancer Research, London have now discovered a protein that actually triggers the growth of blood vessels in breast cancer tumors; this may result in metastization of the cancer to deadly areas, like the brain. “Even where there are 1.8 times as many cancers being diagnosed, mortality is the same”. The 10% increase in breast cancer screening was linked to a 25% rise in small breast cancers, or tumors that are 2 cm or less, Medical News Today reports.
Researchers stress the point that over-diagnosis is happening in populations, but not in individuals. Study author Charles Harding, PhD, disclosed funding from Exegen Corp. Currently, assessment of the impact of mammographic screening programmes can not be made without taking advances in breast cancer treatment into account.
“Sadly, we are left in a conundrum”, the commentary authors wrote. “Women will increasingly approach their physicians with questions and concerns about overdiagnosis, and we have no clear answers to provide”.
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Despite this uncertainty, the study authors endorsed mammograms as a valuable tool to screen women for breast cancer. Furthermore, the best rate of screening mammograms is not “zero”.
