Some Small Tumors In Breasts May Not Be So Bad After All

Scientists say they may have solved a big medical mystery: why mammograms don't save more lives.

A study involving thousands of breast cancer cases, released Wednesday, concludes that a significant proportion of tumors detected through mammography are not small because they are found early.

Instead, the tumors are small because they are biologically prone to slow growth.

"For over 100 years, we've known that small breast cancers have a much better prognosis than large breast cancers," says Donald Lannin, a professor of surgery at the Yale School of Medicine, who led the study. "We always assumed that it was because we were catching the small cancers early and then that's why the cure rate was much better."

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