Breast cancer screening is the process of identifying breast cancer within a person before she has any symptoms related to the disease. For example, a routine screening mammogram may detect very tiny changes within the breast tissue way before a woman or her doctor can feel this abnormality, thus detecting the breast cancer at its very earliest stage. The goal of screening is to detect breast cancer in its early stages. This is opposed to detecting breast cancer when it is in its later stages, usually at which time a person can feel the abnormality in her breast, and the chances that the breast cancer may have spread outside the breast to other parts of the body are increased. Breast cancer detected earlier is easier to treat and has a much more effective cure rate than breast cancer detected in later stages.
Common tests for breast cancer screening
- Clinical and/or self Breast Exam
- Breast Ultrasound
- Breast Magnetic Resonance Imaging (MRI)
- Breast-specific Positron Emission Mammographyactually (PEM) or Breast Specific Gamma Imaging (BSGI)
- Breast biopsy
Typically, the screening regimen for breast cancer detection involves monthly self breast examination, yearly clinical breast exam (performed by your doctor), and yearly mammography. This combined regimen, for the typical average woman, usually begins at age 40. However, for those with particular risk factors for the development of breast cancer, those carrying the breast cancer gene, and those known to have an increased lifetime risk for developing breast cancer, this yearly screening regimen is recommended to begin younger than age 40 (the exact age at which you would be recommended to start will vary on your particular history). Depending on your particular history, additional testing may be recommended to the standard regimen/routine so that you have the very best chance of detection.
Clinical Breast Exam (CBE)
A health care professional physically examines breasts for any physical abnormalities and, if necessary, orders additional testing such as a mammogram or breast ultrasound to confirm a diagnosis. It is also important to do monthly self breast exams.
Mammograms are the most widely available screening test presently available for breast cancer. A mammogram is a low dose x-ray of the breast that can find tumors that are too small to feel with a conventional breast exam. The risk of an undetected breast cancer is far greater than the very minimal risk of the very low amount of radiation given off by a mammogram. As good as mammograms are, their ability to detect cancer is decreased by the presence of dense breast tissue. It is a good idea to know the density of the patient’s breast tissue and to know that there are other imaging tests (such as breast ultrasound and breast MRI) which can significantly increase the breast cancer detection rate when combined with a mammogram.
- Screening mammograms are mammograms performed in women who have no signs or symptoms of cancer relating to their breasts.
- Diagnostic mammograms are mammograms performed in women who are having some type of problem relating to their breast, such as a lump, pain, etc. Sometimes diagnostic mammograms are also performed in women who may not be currently having any problems but have a history of having breast problems.
Ultrasound, also called sonography, is an imaging test which uses sound waves to produce an image of a breast. It does not involve the use of radiation like a mammogram. Ultrasound is often used to determine if a nodule seen on a mammogram is a cyst (fluid filled) or a solid nodule. Ultrasound is also used to further evaluate any problem area(s) in a breast that are not well seen on the mammogram. Breast ultrasound is much better able to identify abnormalities within dense breast tissue compared to mammograms. However, ultrasound should not replace a mammogram as there are some things seen on a mammogram (such as tiny calcium deposits which can be a sign of cancer) which cannot be well seen on the ultrasound.
Breast MRI uses radio waves and magnetic fields to produce detailed pictures of the breast tissue. Similar to ultrasound, it does not involve the use of radiation. However, it does require the use a contrast agent which is injected through an IV and also requires the patient to be partially inside a tube for the scanning process. This contrast agent identifies areas within the breast tissue which have increased blood flow, one possible sign that something in your breasts may be cancerous. Breast MRI is currently the most sensitive test for detecting breast cancer. Breast MRI is very effective in identifying breast cancer within dense breast tissue, unlike mammography. However, breast MRI should not replace your mammogram as there are some things seen on a mammogram (such as tiny calcium deposits which can be a sign of cancer) which cannot be well seen on the MRI. In people with very dense breast tissue and those at increased risk for the development of breast cancer, breast MRI can be very helpful in detecting breast cancer that would not have been identified on their routine annual mammogram.
Breast-specific Nuclear Medicine Imaging Tests: PEM (positron emission mammography) and BSGI (breast specific gamma imaging)
Nuclear medicine breast imaging exams involve the IV injection of a radioactive agent into the bloodstream. After the injection, the patient is put in front of a nuclear medicine camera which produces an image of the breast tissue based on detecting where the radioactive material goes within the breast tissue. This radioactive agent will tend to accumulate within any cancerous areas within the breast. These imaging exams, unlike all the other breast imaging exams, have the drawback of delivering a relatively higher radiation dose. Emerging data is showing that these exams may be a reasonable alternative to breast MRI when a person cannot undergo breast MRI for various reasons (such as having a pacemaker or claustrophobia). Like ultrasound and MRI, nuclear medicine breast imaging exams are not affected by breast density.
Mammograms, breast ultrasound, breast MRIs, breast nuclear medicine exams, and all other breast imaging examinations are interpreted by a radiologist, a medical doctor specializing in the use of medical imaging to diagnose and treat disease. In some centers, the radiologist has completed additional training, called a fellowship, in breast imaging examinations. It is very important that your breast imaging studies are interpreted by a doctor experienced in breast imaging.
Tissue sampling is the process of taking a small amount of normal bodily fluid from the breast tissue and examining it under the microscope to determine if any cancer cells are present. This method can be used to detect cancer at an early stage. The three common techniques are:
- Fine-needle aspiration – inserting a thin needle near the nipple to draw fluid.
- Nipple aspiration – gentle suction with a pump to collect fluid through the nipple.
- Ductal lavage – a catheter is inserted into the nipple with release of salt water into the duct. The water removes the breast cells that are examined for cancer or other abnormalities.
Thermography is based on the premise that cancerous breast tissue is more active than the normal breast tissue and therefore produces more heat than normal breast tissue. By using special cameras and computers (infrared cameras), the temperatures of each region of the breast tissue can be detected and analyzed and then displayed as an image. Areas of the breast tissue that have elevated temperatures may be a sign of cancer within those areas. Thermography is not a replacement for mammograms, breast ultrasound, or breast MRI.
Risks of Screening
- False-negative test results – Test results may appear normal although breast cancer is present, delaying medical attention and treatment.
- False-positive test results – Test results initially appear abnormal leading to more testing and/or breast biopsy; however, when the additional testing and/or biopsy are performed, the final results come back not showing cancer. Initially thinking there was truly an abnormality can cause anxiety for some people.
- Mammography exposes breast to small doses of radiation, and for women over age 40, the benefits of an annual screening far outweigh the risk from radiation exposure.
- Risks and benefits may be different for different people.