LONDON — In the latest major study to consider whether the dangers of mammograms outweigh the benefits, experts say the tests can reduce the chances of dying from breast cancer by 28 percent and that national screening programs should continue.

The debate over the value of mammograms has raged in recent years. A British review in 2012 concluded that for every life mammograms save, about three other women are unnecessarily treated for a cancer that would never have threatened their lives.

In the new study, researchers tracked all Norwegian women aged 50 to 79 between 1986 and 2009, just as a national screening program was getting underway.

The researchers estimated about 368 women need to be given a chance to have a mammogram to prevent one death from breast cancer.