Certain type of hormone therapy increases breast cancer risk, study finds

Women using a certain type of hormone therapy to treat menopause symptoms could be at higher risk for breast cancer, according to a new study. 

The study, published Tuesday in The Lancet Oncology, found that estrogen plus progesterone increases the risk of breast cancer in women under 55 with a uterus, while estrogen alone reduces the risk.

Dr. Céline Gounder, CBS News medical contributor and editor-at-large for public health at KFF Health News, told "CBS Mornings" Wednesday the study participants, all under age 55, were divided into two groups — women who still have their uterus and those who do not, since they require different types of treatment.