Official advice that women should be examining their breasts for signs of cancerous lumps may be wrong, and may even be doing more harm than good.

A new study has found that self-examination isn’t reducing the rate of breast cancer deaths. Researchers at the Nordic Cochrane Centre in Copenhagen, Denmark have found that women who self-examined had 3,406 biopsies performed compared with 1,856 in the group that didn’t examine their breasts. There was no difference between the two groups in the number of breast cancer deaths.

The researchers also question the wisdom of routine screening. They found that for every 2,000 women screened over a 10-year period, one will have her life prolonged. However, 10 women who did not have breast cancer would be wrongly diagnosed, and would suffer distress and treatment unnecessarily. “It’s not clear,” they conclude, “whether screening does more harm than good.”

(Source: Cochrane Database of Systematic Reviews, 2006; 4. art no. CD001877.DOI:10.1002/14651858.CD001877.pub2).