The introduction of routine breast screening may have resulted in more harm than benefits, researchers from the University of Southampton, England, reported in BMJ (British Medical Journal)
. They explain that examples of harms include abnormal results that eventually prove to be normal ones (false positives), and treating patients for cancers that are harmless and would not threaten the woman's lifespan (overtreatment).
Authors James Raftery and Maria Chorozoglou found that the harms caused by routine mammographies generally offset the benefits by nearly ten years, after which the benefits start building up. However, they never accumulate by as much as experts had predicted when screening started.
A 1986 report - the Forrest Report - estimated how many screened and unscreened females would survive over a 15-year period; the estimate was for each year, up to 15 years. The results of the estimate persuaded health authorities in the UK to start routine breast screening.
They worked out costs and benefits in QALYs (quality adjusted life years) - this is a combination of quantity and quality of life measurement. They did not account for harms. They estimated that by introducing routine breast cancer
screening, which they thought had few harms and are not costly, would lower breast cancer mortality rates by nearly one third.
Since 1986, experts have accepted that there are harms associated with routine breast cancer screening. The Southampton researchers set out to update the survival estimates of the report by turning the combined benefits and harms of mammographies into a single measure.A female having a mammogram
They gathered data on 100,000 females, all aged 50+ years who survived up to two decades after initially entering the mammography program.
The researchers established that the benefits of screening were approximately halved when false...