A new study suggests that increased awareness and improved treatments rather than mammograms are the main force in reducing the breast cancer death rate. The study, medical experts say, is the first to assess the benefit of mammography in the context of the modern era of breast cancer treatment. While it is unlikely to settle the debate over mammograms -- and experts continue to disagree about the value of the test -- it indicates that improved treatments with hormonal therapy and other targeted drugs may have, in a way, washed out most of mammography's benefits by making it less important to find cancers when they are too small to feel. Previous studies of mammograms done decades ago, found they reduced the breast cancer death rate by 15 percent to 25 percent, a meaningful amount. But that was when treatment was much less effective. In the new study, mammograms, combined with modern treatment, reduced the death rate by 10 percent, but the study data indicated that the effect of mammograms alone could be as low as 2 percent or even zero. The study, published Thursday in The New England Journal of Medicine, looked at what happened in Norway before and after 1996, when the country began rolling out mammograms for women ages 50 to 69 along with special breast cancer teams to treat all women with breast cancer. The study is not perfect. The ideal study would randomly assign women to have mammograms or not. But, cancer experts said, no one would do such a study today when mammograms are generally agreed to prevent breast cancer deaths. In the study, which is continuing, women were followed for a maximum of 8.9 years. It is possible that benefits may emerge later. Nonetheless, the new study is 'very credible,' said Dr. Barnett Kramer, associate director for disease prevention at the National Institutes of Health. 