Announced on Tuesday, the advice is aimed toward women at "average" risk for breast cancer, and doctors suggest more screening for women at higher risk. Higher risk factors include certain genetic mutations and family history of cancer. "The most important message of all is that a mammogram is the most effective thing that a woman can do to reduce her chance of dying from breast cancer," said Dr Richard Wender of the American Cancer Society. Breast cancer is uncommon for women under 40 and starting mammograms too early may result in "false alarms", he said.