(July 9, 2009 - Insidermedicine) As many as one in three breast cancers uncovered by mammography screening programs are likely harmless and require no treatment, according to research published in the British Medical Journal.

Among 1,000 women who undergo mammography to screen for breast cancer once a year for 10 years:

•    One woman's life will be saved

•    2-10 women will be treated needlessly

•    10-15 women will be diagnosed with breast cancer sooner, but this will not affect their prognosis

Researchers from the Nordic Cochrane Centre in Copenhagen analyzed trends in breast cancer incidence several years before mammography screening programs were introduced. They then compared these trends with those occurring after screening programs were introduced.

After the introduction of screening programs, overdiagnosis was estimated to be as high as 52%. That translates to as many as one in three cancers diagnosed in this manner actually being an overdiagnosis.

We had a chance to speak with Dr. Karsten Jørgensen, the principal investigator of this study, who offered some further insight.

Today's research highlights the rate at which mammography screening programs overdiagnose breast cancer and demonstrates a need to weigh the pros and cons of such programs.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.