Breast Cancer Chapter 8
Screening for Cancer
Breast Cancer Screening
"Screening" means checking for a disease when there are no symptoms of that disease present. Types of screening for breast cancer include breast self-exam, clinical breast exam, and mammograms. Screening is important because it helps to detect breast cancers earlier, when they are at a less-advanced stage and easier to treat. The American Cancer Society gives the following recommendations (recommendations and methods for breast cancer screening may vary in other countries):
- Breast self-exam (BSE) is an option for women starting in their 20s.
- Clinical breast exam (CBE) should be part of a periodic health exam, about every 3 years for women in their 20s and 30s and every year for women 40 and over.
- Yearly mammograms are recommended for all women starting at age 40, and continuing for as long as the woman is in good health.
- Women at high risk should have a magnetic resonance imaging (MRI) scan and a mammogram every year, beginning at age 30. Women at moderately increased risk should talk with their doctors about having an MRI scan in addition to their yearly mammogram.
Breast Self-Exam (BSE)
When done correctly and regularly, breast self-exam (BSE) can help save lives. Women who perform BSE are more likely to be diagnosed with smaller tumors, and cancer is less likely to have spread to their underarm lymph nodes. An important part of BSE is self-awareness. Women should be aware of what their breasts normally feel and look like so that they notice any change, and they should bring that change to the attention of their doctor immediately.
Clinical Breast Exam (CBE)
Clinical breast exam (CBE) is a physical exam of the breast performed by a health-care provider to check for lumps or other changes. CBE can detect 7-10% of tumors that can't be seen on a mammogram; 14-21% of breast cancers are detected by CBE. CBE is usually done as part of routine annual care for women over age 35. It should include inspection and palpation of the breast and the nearby lymph nodes.
Mammograms use low-dose X-rays to create images of the breast on film. These pictures are examined by radiologists for abnormalities. Mammograms are considered the gold standard for breast cancer screening, and the benefits of screening mammograms are well established. Studies have shown that women age 40-49 live longer if they have breast cancer screening. In women age 50 or over, annual mammograms reduce the mortality rate by 25-35%. Many major medical organizations in the US, including the ACS, the American College of Radiologists, and the American Medical Association, recommend that women have annual mammograms beginning in their 40s. The National Cancer Institute recommends that women age 40-50 have a mammogram every 1-2 years.
Mammograms aren't perfect. They catch 85-90% of breast tumors, but miss 10-15% of tumors that could be detected by CBE. That's why CBE and mammograms are complementary and should both be a part of regular cancer screening. Another limitation of mammography is that a certain number of false positives will occur; that is, mammograms can detect noncancerous lesions that require follow-up, including biopsy. Mammography also requires the breasts to be compressed between plates while the image is captured, which may be uncomfortable or even painful for some women. Typically, two views are taken of the breast: cranial-caudal (top to bottom) and mediolateral oblique (angled side view). Mammograms expose the breast to X-ray radiation, although the dosage is lower now than in the early days of mammography and is not thought to be hazardous.
In traditional mammography, X-ray images of the breast are captured on film. In digital mammography, the images are captured using a special electronic X-ray detector, which converts the image into a digital picture. The digital mammogram is then stored on a computer. The magnification, orientation, brightness, and contrast of the image can be altered to aid the radiologist in analyzing the results.
Studies of digital mammography have shown that it is comparable to film mammography in terms of detecting breast cancer. However, digital mammography is in its infancy and results can be expected to improve as radiologists become more familiar with its techniques.
Computer-Aided Detection (CAD)
With computer-aided detection (CAD), mammogram images (either digital or film) can be scanned by a computer to bring any suspicious areas to the attention of the radiologist.
Calcifications are tiny mineral deposits in the breast tissue that appear as white spots in mammograms. There are two types of calcifications:
- Microcalcifications are tiny, measuring less than .02 inch (.5 mm). A cluster of microcalcifications may indicate a small cancerous tumor or DCIS. About half of the cancers detected by mammography appear as a cluster of microcalcifications, and they are the most common sign of DCIS. Only about 17% of calcifications requiring biopsy are cancerous.
- Macrocalcifications are large calcium deposits associated with fibrocystic or degenerative changes in the breast. They are not linked with cancer and don't usually require a biopsy.
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