Screening Techniques

Tests and exams

The goal of screening tests and exams, is to find breast cancer before it starts to cause symptoms. Breast cancers that are found because they can be felt tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening exams are more likely to be small and still confined to the breast. The size of a breast cancer and how far it has spread are important factors in predicting the prognosis (outlook) for a woman with this disease.

Breast self exam (BSE)

Breast self exam (BSE) is an option for women starting in their 20s. Women should be told about the benefits and limitations of BSE. Women should report any breast changes to their health professional right away.

Research has shown that BSE plays a small role in finding breast cancer compared with finding a breast lump by chance or simply being aware of what is normal for each woman. Some women feel very comfortable doing BSE regularly (usually monthly after their period) which involves a systematic step-by-step approach to examining the look and feel of their breasts. Other women are more comfortable simply looking and feeling their breasts in a less systematic approach, such as while showering or getting dressed or doing an occasional thorough exam. Sometimes, women are so concerned about "doing it right" that they become stressed over the technique. Doing BSE regularly is one way for women to know how their breasts normally look and feel and to notice any changes. The goal, with or without BSE, is to report any breast changes to a doctor or nurse right away.
Women who choose to do BSE should have their BSE technique reviewed during their physical exam by a health professional. It is okay for women to choose not to do BSE or not to do it on a regular schedule. However, by doing the exam regularly, you get to know how your breasts normally look and feel and you can more readily detect any signs or symptoms if a change occurs, such as development of a lump or swelling, skin irritation or dimpling, nipple pain or retraction (turning inward), redness or scaliness of the nipple or breast skin, or a discharge other than breast milk. Should you notice any changes you should see your health care provider as soon as possible for evaluation. Remember that most of the time, however, these breast changes are not cancer.

Clinical breast exam

During a clinical breast exam, your health care provider checks your breasts. You may be asked to raise your arms over your head, let them hang by your sides, or press your hands against your hips.

Your health care provider looks for differences in size or shape between your breasts. The skin of your breasts is checked for a rash, dimpling, or other abnormal signs. Your nipples may be squeezed to check for fluid.

Using the pads of the fingers to feel for lumps, your health care provider checks your entire breast, underarm, and collarbone area. A lump is generally the size of a pea before anyone can feel it. The exam is done on one side and then the other. Your health care provider checks the lymph nodes near the breast to see if they are enlarged.

If you have a lump, your health care provider will feel its size, shape, and texture. Your health care provider will also check to see if the lump moves easily. Benign lumps often feel different from cancerous ones. Lumps that are soft, smooth, round, and movable are likely to be benign. A hard, oddly shaped lump that feels firmly attached within the breast is more likely to be cancer, but further tests are needed to diagnose the problem

Mammogram

A mammogram is an x-ray picture of tissues inside the breast. Mammograms can often show a breast lump before it can be felt. They also can show a cluster of tiny specks of calcium. These specks are called microcalcifications. Lumps or specks can be from cancer, precancerous cells, or other conditions. Further tests are needed to find out if abnormal cells are present.

If the mammogram shows an abnormal area of the breast, your doctor may order clearer, more detailed images of that area. Doctors use diagnostic mammograms to learn more about unusual breast changes, such as a lump, pain, thickening, nipple discharge, or change in breast size or shape. Diagnostic mammograms may focus on a specific area of the breast. They may involve special techniques and more views than screening mammograms. To learn more about mammograms, you may want to read the NCI fact sheet Mammograms or review the frequently asked questions that follow.

Mammogram Frequently Asked Questions

1. What is a mammogram?

A mammogram is an x-ray picture of the breast.

Mammograms can be used to check for breast cancer in women who have no signs or symptoms of the disease. This type of mammogram is called a screening mammogram. Screening mammograms usually involve two x-ray pictures, or images, of each breast. The x-ray images make it possible to detect tumors that cannot be felt. Screening mammograms can also find microcalcifications (tiny deposits of calcium) that sometimes indicate the presence of breast cancer.

Mammograms can also be used to check for breast cancer after a lump or other sign or symptom of the disease has been found. This type of mammogram is called a diagnostic mammogram. Signs of breast cancer may include pain, skin thickening, nipple discharge, or a change in breast size or shape; however, these signs may also be indicators of benign conditions. A diagnostic mammogram can also be used to evaluate changes found during a screening mammogram or to view breast tissue when it is difficult to obtain a screening mammogram because of special circumstances, such as the presence of breast implants.

2. How are screening and diagnostic mammograms different?

Diagnostic mammography takes longer than screening mammography because more x-rays are needed to obtain views of the breast from several angles. The technician may magnify a suspicious area to produce a detailed picture that can help the doctor make an accurate diagnosis.

3. What are the benefits of screening mammograms?

Early detection of breast cancer with screening mammography means that treatment can be started earlier in the course of the disease, possibly before it has spread. Results from randomized clinical trials and other studies show that screening mammography can help reduce the number of deaths from breast cancer among women ages 40 to 74, especially for those over age 50. However, studies conducted to date have not shown a benefit from regular screening mammography in women under age 40 or from baseline screening mammograms (mammograms used for comparison) taken before age 40.

4. What are some of the potential harms of screening mammograms?

Finding cancer does not always mean saving lives Even though mammograms can detect malignant tumors that cannot be felt, treating a small tumor does not always mean that a woman's life will be saved. A fast-growing or aggressive cancer may have already spread to other parts of the body before it is detected. In addition, screening mammograms may not help a woman who is suffering from other, more life-threatening health conditions.
False-negative results False-negative results occur when mammograms appear normal even though breast cancer is present. Overall, screening mammograms miss up to 20 percent of breast cancers that are present at the time of screening.
The main cause of false-negative results is high breast density. Breasts contain both dense tissue (i.e., glandular tissue and connective tissue, together known as fibroglandular tissue) and fatty tissue. Fatty tissue appears dark on a mammogram, whereas dense tissue and tumors appear as white areas. Because fibroglandular tissue and tumors have similar density, tumors can be harder to detect in women with denser breasts.
False-negative results occur more often among younger women than among older women because younger women are more likely to have dense breasts. As a woman ages, her breasts usually become more fatty, and false-negative results become less likely. False-negative results can lead to delays in treatment and a false sense of security for affected women.
False-positive results False-positive results occur when radiologists decide mammograms are abnormal but no cancer is actually present. All abnormal mammograms should be followed up with additional testing (diagnostic mammograms, ultrasound, and/or biopsy) to determine whether cancer is present.
False-positive results are more common for younger women, women who have had previous breast biopsies, women with a family history of breast cancer, and women who are taking estrogen (for example, menopausal hormone therapy).
False-positive mammogram results can lead to anxiety and other forms of psychological distress in affected women. The additional testing required to rule out cancer can also be costly and time consuming and can cause physical discomfort.
Overdiagnosis and overtreatment Screening mammograms can find cancers and cases of ductal carcinoma in situ (DCIS, a noninvasive lesion in which abnormal cells that may become cancerous form in the lining of breast ducts) that need to be treated. However, they can also find cancers and cases of DCIS that will never cause symptoms or threaten a woman's life, leading to "overdiagnosis" of breast cancer. Treatment of these latter cancers and cases of DCIS is not needed, leading to "overtreatment." Overtreatment exposes women unnecessarily to the adverse effects associated with cancer therapy.
Because doctors cannot currently distinguish cancers and cases of DCIS that need to be treated from those that do not, they are all treated.
Radiation exposure Mammograms require very small doses of radiation. The risk of harm from this radiation exposure is low, but repeated x-rays have the potential to cause cancer. The benefits, however, nearly always outweigh the risk.
Women should talk with their health care providers about the need for each x-ray. In addition, they should always let their health care provider and the technician know if there is any possibility that they are pregnant.

Photograph: Catherine Metzger