Chapter 157 Mammography
THE CHALLENGE
To improve the use of breast imaging to detect occult disease.
Scope of the Problem: Widespread use of mammography has been credited with reducing the mortality rate from breast cancer by up to 30%. Unfortunately, not all women receive appropriate screening on a regular basis. One study indicated that only 39% of women aged 50 to 59 and 36% of women aged 60 to 69 had had a mammogram in the preceding year. In another study, only 24% of women older than age 65 followed the current recommendations for annual examinations. It has been estimated that breast cancer mortality could be reduced by as much as one half if all women older than 40 received annual screening. In one study, 6 cancers per 1000 screening mammograms were found, and 3 additional cancers per 1000 annual repeat studies were detected.
TACTICS
Relevant Pathophysiology: Mammography is the best mode of screening for early lesions currently available. Mammography localizes, documents, objectifies, and identifies other occult pathologic changes. Approximately 85% of breast cancers found by mammography are early-stage lesions versus 54% to 70% found by physicians and 38% to 64% of tumors found by the patient herself during breast self-examination. Approximately 35% of breast cancers are found with an abnormal mammogram, without a palpable mass present. Mammography can identify small lesions (1 to 2 mm), calcifications, or other changes suspicious for malignancy about 2 years before a lesion is clinically palpable. Ten-year disease-free survival for patients with these lesions is 90% to 95%. The average lesion found on breast self-examination is 2.5 cm, and half of these patients have nodal involvement. For these patients, 10-year survival falls to between 50% and 70%. More than one third of occult breast cancers have calcifications, making the otherwise-undetected tumors visible through mammography.
Strategies: The American Cancer Society guidelines for mammographic screening are the following:
