This guideline is a departure from the Society's previous guideline which recommended that women 40-49 receive mammograms every year or two and women 50 and over receive annual mammograms.

"This new guideline is based on research evidence, which overwhelmingly points to a benefit from annual mammographic screening for women beginning at age 40," says Myles Cunningham, MD, President of the American Cancer Society. "By beginning a program of annual screening at age 40, women can give themselves the best chance of detecting cancer early, when there is a higher opportunity for long-term survival and more treatment options."

The new guideline emerged at the conclusion of a workshop held March 7-9 during which experts heard data from clinical trials around the world and information on indirect measures of mammography's effectiveness, such as the increase in the number of early stage tumors found and the corresponding decrease of late-stage tumors, and the decrease in tumor size. The Society's Board of Directors then evaluated the evidence along with the workshop's report before voting on the recommendation.

The public debates about mammography screening, especially for women in their 40s, have confused women of all ages and their doctors, too. As such, the Society has made a commitment to creating educational materials that clearly explain both the benefits and limitations of mammography in order to help each woman decide for herself what is best. The Society has also pledged to continue its work to increase the quality of mammography across the country and its efforts into researching the causes of breast cancer and how best to prevent, diagnose, and treat the disease.

"We are confident this guideline is appropriate," says Marilyn Leitch, MD, a surgical oncologist who chairs the American Cancer Society's Breast Cancer Advisory Committee. "Since evidence shows that breast cancers in women in their forties may grow faster than those in older women, this new recommendation for annual screening should result in a greater reduction of deaths."

Some of the data the Society used in evaluating the effectiveness of mammography for women in their forties included:

• a meta-analysis (a compilation of many studies) of eight randomized clinical trials, which found an 18% reduction in breast cancer deaths among women age 40-49;
• results from randomized clinical trials, including two Swedish trials which showed a 44% and a 36% reduction in breast cancer deaths after 12 years of follow-up.
• surrogate, or indirect, measures, which have shown a stage shift toward earlier stage at diagnosis and increased detection of smaller tumors.

"We don't have enough knowledge to say which women will benefit the most from screening, especially among women intheir forties, or which women will not benefit at all. It is just prudent to offer screening to all women 40 and older with the confidence that overall, mammography's lifesaving benefits far outweigh its limitations," Dr. Cunningham said.