evidence: Breast cancer rates increasing among younger women [...] Getty ImagesDiagnoses of breast cancer have increased steadily in women under age 50 over the past two decades, with steeper increases in more recent years, according to a study led by researchers at Washington University School of Medicine in St. Louis. The surge is driven largely by increases in the number of women diagnosed with estrogen-receptor positive tumors, cancerous growths fueled by estrogen. [...] "For most women, regular breast cancer screening does not begin until at least age 40, so younger women diagnosed with breast cancer tend to have later-stage tumors, when the disease is more advanced and more difficult to treat," said senior author Adetunji T. Toriola, MD, PhD, a professor of surgery and co-leader of the Cancer Prevention and Control Program at Siteman Cancer Center, based at Barnes-Jewish Hospital and Washington University School of Medicine. "This research offers a way to begin identifying the factors driving these increasing rates, with the goal of finding ways to slow or reverse them. It also could help identify young women who are at high risk of developing early-onset breast cancer, so that we can design interventions to evaluate in clinical trials to see if we can lower that risk."