NEW YORK — Most women don't need a mammogram in their 40s and should get one every two years starting at 50, a government task force said Monday. It's a major reversal that conflicts with the American Cancer Society's long-standing position.

Also, the task force said breast self-exams do no good and women shouldn't be taught to do them.

For most of the past two decades, the cancer society has been recommending annual mammograms beginning at 40.

But the government panel of doctors and scientists concluded that getting screened for breast cancer so early and so often leads to too many false alarms and unneeded biopsies without substantially improving women's odds of survival.