Which of the following statement(s) is/are true concerning mammography?

a. Up to 50% of cancers detected mammographically are not palpable

c. The sensitivity of mammography increases with age

d. The American Cancer Society currently recommends routine screening mammography beginning at age 40

Although mammography has been available for years, it did not become widely used until the findings of the Health Insurance Plan of New York and the Breast Cancer Detection Demonstration project studies of screening mammography were disseminated. These and other investigators demonstrated that 10%–50% of cancers detected mammographically are not palpable. Conversely, palpation recognizes 10%–20% of tumors not detectable mammographically. The incidence of breast cancer begins to rise sharply at age 40, and the sensitivity of mammograms increases with age as the dense parenchymal tissue of young women is progressively replaced by fatty tissue. Routine screening mammography has been shown to decrease breast cancer-related mortality in asymptomatic women over the age of 50. Controversy exists concerning the role of screening in younger woman. However, currently the American Cancer Society recommends that mammographic screening begin at age 40. Although sensitive, mammography is not specific. Only about 25% of nonpalpable lesions detected mammographically are found to be malignant at biopsy. A spiculated density with ill-defined margins on mammogram is almost certainly malignant. Most commonly, features are seen that are suggestive but not diagnostic of cancer. These include clustered microcalcifications, asymmetric density, ductal asymmetry, and distortion of normal breast architecture and/or skin or nipple distortion.