There are many reasons why it may be more difficult to show a life-saving benefit of screening mammography in younger women.

These facts are especially discouraging to researchers who continue to uncover health-saving and possibly life-saving benefits of mother's milk to the newborn child.

But Federal officials and other safety experts say that those risks are minor compared with the life-saving benefits of the bags.

If the new rule takes effect, it could make tens of thousands of additional Medicare enrollees eligible for the potentially life-saving benefit.

'Astounding Result' The life-saving benefit was found even though only 46 percent of the screened group took all 11 of the offered tests.

"It's second only to seat belts in terms of life-saving benefits," said Susan Ferguson, senior vice president for research at the insurance institute.

The F.D.A. and its advisers have become far less tolerant of risks in medicines that offer few life-saving benefits.

In 1986 he was awarded for his role in creating a nationwide advertising campaign promoting the life-saving benefits of mammography.

We believe he may be tougher on the ones that have less life-saving benefit.

But, he emphasized, the life-saving benefits themselves are not established for younger women.