PITTSBURGH -- Researchers reviewed two large studies of nearly 400,000 women.

The study concluded there is no evidence that the doing breast exams decreases deaths from breast cancer.

It may actually cause unnecessary biopsies.

The study found women who performed self exams had twice as many biopsies that turned out to be negative, compared to women who didn't do the exams.

Experts at the American Cancer Society said their guidelines were changed in 2003 after similar studies were released.

It no longer recommend monthly breast self-exams, it says women should be informed of the potential risks and benefits of the test.

The study was done by the Cochrane Collaboration