A new study in Australia has suggested that almost one in four invasive breast cancers in women of ages between 50 to 69 years is not fatal.
The research has further heated up the question: what part of abnormalities picked up by the mammogram tests can actually threaten life?
Epidemiologist Dr Stephen Morrell of the University of Sydney and her colleagues studied cases in New South Wales and found that the number of women diagnosed with breast cancer and aged between 50-69 increased almost two times after tests began.
However, tests of women outside this age group did not show a similar leap.
The researchers concluded that tests were even showing up cases where cancer-growth was very slow.
"Some of those early-diagnosed cases would not manifest clinically during that woman's lifetime," ABC Online quoted Morrell, as saying.
He added that nearly 23precent to 29precent of all invasive breast cancers cases in NSW are "over-diagnosed".
The researchers whose study centered on invasive cancer say that the current rate of 25precent over-diagnosis is the "price" that people must for the benefits of screening.
While admitting that over-diagnosis was a "very vexing issue", Professor David Roder from the Cancer Council South Australia in Adelaide said: "I think there are equally rigorous studies that come to different conclusions."