Breast cancer screening. Interpreting new data for clinical practice.

While multiple trials support routine mammography for women aged 50 to 69 demonstrating a reduction in breast cancer deaths by about 30%, experts disagree on breast cancer screening recommendations for women 40 to 49 years old. A review of the data and its interpretation illustrate the areas of controversy: lack of statistical power, prolonged screening intervals, suboptimal mammographic technical quality, and difficulty applying the data to current mammographic screening practice. Clinical decision making for health care providers and women aged 40 to 49 is guided by understanding the risk of breast cancer and weighing the risk and benefits of screening mammography. Further research to resolve whether breast cancer screening is effective in decreasing breast cancer deaths in women aged 40 to 49 is needed.