Harvard study of 16 million women reveals that screenings of breast cancer may not be helping the reduction of deaths but, may be actually leading to over-diagnosis. ‘False positives’ have taken place due to routine screening in which they were wrongly told they might have breast cancer when, in fact, they do not.
Breast cancer deaths in areas with screening were not lower than the areas with fewer screening; in fact, areas of the nation with higher levels of it diagnosed more tumors. Charles Harding, the study’s lead author from Seattle, Washington, warns that the mortality results observed were far from definitive. The most outrageous discovery of this study was the instantaneously apparent and important evidence of breast cancer over-diagnosis.
National Cancer Institute suggests, roughly, 230,000 U.S. women are newly diagnosed with breast cancer every year. Although screening guidelines vary, average-risk women should have mammograms every other year between ages 50 and 74, and getting screened before age 50 should be an individual decision; according to the government-backed U.S. Preventive Services Task Force.
The new research involved close to 16 million women, living in 547 U.S. counties in the year 2000, where all of them were at least 40 years old. The study analyzed breast cancer screenings, cancer diagnoses, tumor characteristics and deaths. The percentage of women with screening mammograms ranged from 39 percent to 78 percent, depending on where they lived. More than 53,000 women were diagnosed with breast cancer in 2000.
The number of breast cancer diagnoses rose with the number of screenings but, the amount of breast cancer deaths over the next 10 years remained the same, according to the report by researchers in JAMA Internal Medicine.
At Queen Mary University of London, a study of ten million identified that routine breast screening cuts cancer deaths by 40 per cent among middle-aged women. This is basically around eight deaths prevented per 1,000 women regularly attending screening in the UK.
Back in the U.S., an overall 10 percentage point rise in breast cancer screenings would be linked to a 16 percent increase in breast cancer diagnoses. But, the number of breast cancer deaths had was not affected by the number of screening mammograms performed.
Harding found it troubling that no evidence was found of a mortality benefit from screening, especially because there was no relationship between screening and advanced-stage cancer. But he added that the findings were quiet uncertain for mortality because the data is very ‘noisy’.
Dr. Joann Elmore and Ruth Etzioni of the University of Washington in Seattle agree in an editorial that the study’s results are limited by the potential of ecological bias, which can occur when assumptions are made about individuals from data of a large group. They also showed concern on regarding the matter that other unmeasured factors may account for the lack of difference in breast cancer deaths.
