Radiologic examination of the female breast with equipment and techniques designed to screen for cancer.
Mammography can detect carcinoma of the breast sometimes as early as 2 years before a lesion becomes palpable and in many cases before lymph node metastasis has occurred. Mammographic findings that strongly suggest carcinoma are ill-defined densities within breast tissue and microcalcifications. These findings are not specific, however, and the cumulative probability of a woman's having a false-positive mammogram during 10 years of annual examinations approaches 50%. Numerous clinical studies seem to support the value of mammography in reducing the mortality of breast cancer, particularly in women aged 50–69 years. Although some observers have questioned the validity of these studies, the balance of opinion favors a substantial life-sparing role for mammographic screening in both middle-aged and elderly women. Magnetic resonance imaging (MRI) may detect tumors at an earlier stage than mammography, and has been recommended by some authorities for annual surveillance of women at high risk. Scintimammography after intravenous injection of technetium 99m sestamibi may be used to follow up an equivocal mammogram. Positron emission tomography has shown promise in discriminating between benign and malignant breast masses as well as in detecting axillary lymph node metastases in patients with newly diagnosed breast cancer and distant metastases in patients with advanced or recurrent breast carcinoma. Because of the high cost of this procedure, its use is limited to high-risk subjects and those with dense breasts. The higher density of breast tissue in younger women limits the ability of radiography to identify tumors in women between ages 40 and 50, for whom ultrasonography is preferred in evaluation of palpable breast lesions. Research has suggested that for a small fraction of women, exposure to radiation during mammography may actually trigger breast cancer. The American Cancer Society, the National Cancer Institute, and the American College of Radiology recommend a baseline mammogram for every woman by age 40 and annual mammograms after age 50. Mammograms should begin at age 25 for women who are at special risk because of family history. Because some 10% of breast cancers that can be palpated on examination are missed by mammography, annual examination of the breasts by a physician is also recommended. Digital scanning further enhances the detection of microcalcifications and spiculated masses on mammography. However, mammography remains a screening procedure, and diagnosis of breast lesions depends on physical examination and biopsy findings. Federal law requires all facilities in the U.S. that perform mammography provide the examinee with a report of the results in clear, simple language within 30 days after the examination, besides providing a detailed report to the physician who ordered the examination.
Reference: Stedman's Medical Dictionary