Breast cancer screening: who should be included? The recommendations of the U.S. Preventive Services Task Force are reviewed in regard to screening for breast cancer. In contradistinction to those issued by some other national organizations, screening for breast cancer using mammography at ages 40-49 is not recommended. It is concluded that the scientific evidence is insufficient at present to recommend mammography screening for women aged 40-49. The recommendations of the task force are: all women over age 40 should receive an annual breast examination; all women should have mammography every one or two years beginning at age 50 and concluding at approximately age 75 unless disease has been detected; and it may be prudent to begin mammography at an earlier age for women at high risk of breast cancer. These recommendations are appropriate in light of the available evidence; though at present there is no evidence that clinical examination of the breasts at any age reduces breast cancer mortality; the upper age beyond which breast cancer screening no longer has a significant effect in reducing breast cancer mortality is unknown; and there is no evidence that women at high risk for breast cancer benefit to a different degree from screening than women not at high risk. 