Bulletin Today | Personal Health“Screening saves lives” has long been the mantra of breast cancer groups and doctors. But a longtime critic of Americans’ zeal for screening says new research shows that up to a third of cancers detected through routine mammograms may not be life-threatening. The study, which looked at three decades of government data on early-stage breast cancer in women over 40, found that 70,000 women a year may have been overdiagnosed for breast cancer and needlessly treated. “It’s a lot of …