Narrator:          This is Science Today. New research from the University of California, San Francisco suggests that 70 percent of women diagnosed with a non-invasive breast cancer called ductal carcinoma in situ, or DCIS, have been receiving unnecessarily aggressive therapies for their condition — even though few DCIS patients actually go on to develop deadly tumors.

Kerlikowske:     About half of women with DCIS are getting lumpectomy and radiation and about a third are getting mastectomy and a third a lumpectomy. So, people are getting very aggressive treatment when we know that only 15 percent of those lesions will actually go on to be invasive cancer over 10 years.

Narrator:          Study leader Karla Kerlikowske examined the medical histories of more than 1,600 DCIS patients and developed a model that can predict which patients are at most risk for invasive cancer and which can opt for less aggressive treatment.

Kerlikowske:     So, I think the public health implication is that we could stop treating at least a group of people with DCIS as aggressively as is being treated right now.

Narrator:           For Science Today, I'm Larissa Branin.