Top: Women receive intravenous chemotherapy. Visual: E+ via Getty Images Fluorouracil can be deadly for patients who slowly metabolize it. But U.S. doctors don’t often test for those at risk. BY ARTHUR ALLEN ONE JANUARY morning in 2021, Carol Rosen took a standard treatment for metastatic breast cancer. Three gruesome weeks later, she died in excruciating pain from the very drug meant to prolong her life. Rosen, a 70-year-old retired schoolteacher, passed her final days in anguish, enduring severe diarrhea and nausea and terrible sores in her mouth that kept her from eating, drinking, and, eventually, speaking. Skin peeled off her body. Her … Continue reading A Common Gene Test Could Save Lives From Chemo Drug Overdose