Pill Puzzle: Do antibiotics increase breast cancer risk?

After poring over the pharmacy records of more than 10,000 women, researchers have identified a disturbing correlation: Women in the study who had breast cancer tended to have a history of heavier antibiotic use than cancerfree women. Although this study raises the concern that taking microbe-killing drugs increases a woman’s risk of breast cancer, the investigators stress that there may be more plausible explanations for the unexpected finding.