|
Page 1 of 4  The goal of screening for breast cancer is to decrease the chances that a woman will die due to breast cancer. Screening can find cancers early, when they are most treatable. Approaches used over the past several decades to finding breast cancer early include mammography, breast self-examination (women systematically search for lumps in their own breasts), and clinical breast examination (doctors or nurses examine women's breasts for lumps). Section 1: Breast Cancer Screening
1. What is a mammogram?
A mammogram is an x-ray 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 taking two x-rays of each breast. Together, these four x-rays deliver an effective radiation dose that is about the same as the average person receives from naturally occurring background radiation during a three month period of time. These mammograms make it possible to detect cancer that cannot be felt. Screening mammograms can find microcalcifications (tiny deposits of calcium) and changes in breast tissue 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 breast cancer 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. A diagnostic mammogram may also be used to further evaluate abnormal findings from a screening mammogram.
2. What does the latest NCI-sponsored research tell us about mammography?
In 2009 NCI sponsored a study to model the benefits and harms associated with specific screening schedules at various ages (for example, one comparison looked at annual vs. every other year mammography screening at various ages). To translate the available evidence into health outcomes associated with specific screening programs, computer models made assumptions related to the progression of disease (for example, whether no disease would develop, slowly progressing disease would develop or rapidly progressing disease would occur). For this evaluation, there were six independently developed models, each including unique assumptions but estimating the same outcomes. The independent nature of the models means that the comparative analyses of results were enriched because there was consistency seen across the models.
There were very similar results across the six models studied, with a median reduction in breast cancer mortality of 16.5 percent for women ages 50 to 69 who were screened every other year. Nearly equivalent results were found when looking at a wider age group of 40 to 69. These models have been used to inform decision making by various organizations that are tasked with developing screening recommendations.
[Reference: "Effects of Mammography Screening Under Different Screening Schedules: Model Estimates of Potential Benefits and Harms," J.S. Mandelblatt, K.A. Cronin, S. Bailey, D.A. Berry, H.J. de Koning, G. Draisma, H. Huang, S.J. Lee, M. Munsell, S.K. Plevritis, P. Ravdin, C.B. Schechter, B. Sigal, M.A. Stoto, N.K. Stout, N.T. van Ravesteyn, J. Venier, M. Zelen, and E.J. Feuer, for the Breast Cancer Working Group of the Cancer Intervention and Surveillance Modeling Network (CISNET). Nov. 17, 2009. Annals of Internal Medicine. Vol. 15, No. 10, pp 738-747].
3. What is the best method of detecting breast cancer?
There is no simple answer to this question because it depends on factors such as age and breast density. Standard screen-film mammography that takes a picture with x-rays and uses film is the most widely available technique, and it has been shown to reduce mortality when used regularly in women ages 40 to 74. Digital mammography is becoming more widely available, and it may find cancer more effectively in women with dense breast tissue. Screen-film mammography finds cancer better in women with low density breast tissue. On average, younger women are more likely to have dense breast tissue but once a woman has a screen-film mammogram she can ask her radiologist about her breast density, and she can talk with her health care provide to develop a plan that is best for her.
As with any screening test, screening mammograms have limitations. For example, some cancers cannot be detected by screening mammograms.
Checking one's own breasts for lumps or other unusual changes is called a breast self-exam. Breast self-exams cannot replace regular screening mammograms. In clinical trials, systematically teaching breast self-exams did not reduce the number of deaths from breast cancer, but that does not mean that women should not examine their breasts or report symptoms. If a woman chooses to do breast self-exams, it is important to remember that breast changes can occur because of pregnancy, aging, menopause, taking birth control pills or other hormones, and during menstrual cycles. It is normal for breasts to feel a little lumpy and uneven. It is also common for breasts to be swollen and tender right before or during a menstrual period. If a woman notices any unusual changes in her breasts, she should contact her health care provider.
A physical exam of the breasts by a trained medical professional is called a clinical breast exam. Some evidence suggests that clinical breast exams may help reduce the number of deaths from breast cancer, but this evidence is not as strong as the evidence for mammography.
4. What are some of the limitations or harms of screening mammograms?
* Finding cancer does not always mean saving lives-- Even though mammograms can detect breast changes that cannot be felt, finding these changes does not always mean a woman benefits. Some changes may represent conditions that will reverse to normal breast tissue, and some will not affect a woman's life, even if they are cancer. For some women it may be more important to focus on treating other conditions, improving their physical activity, and eating well than it is to get screened.
* False negatives--False negatives occur when mammograms appear normal even though breast cancer is present. Overall, screening mammograms miss up to 15 percent to 25 percent of breast cancers that are present at the time of screening. False negatives occur more often in younger women than in older women because the dense breasts of younger women make breast cancers more difficult to detect in mammograms. As women age, their breasts usually become more fatty (therefore, less dense), and breast cancers become easier to detect with screening mammograms.
* False positives--False positives occur when radiologists decide mammograms are abnormal but no cancer is actually present. Abnormal mammograms should be followed up with additional testing (a diagnostic mammogram, ultrasound, and/or biopsy) to determine if further investigation is necessary. False positives are more common in 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, hormone replacement therapy).
* Radiation exposure-- Mammograms (as well as dental x-rays and other routine x-rays) use very small doses of radiation. The risk of any harm is very slight, but benefits often outweigh the risks. Repeated x-rays, however, could cause harm. Women should talk with their health care provider about the need for each x-ray. In addition, they should always let their health care provider, and the technician taking the x-ray, know if there is any possibility that they are pregnant.
* Over-diagnosis-- Mammography can detect cancers that otherwise would never have caused symptoms in a woman's lifetime, and thus lead to unnecessary treatment.
5. Why are mammograms not routinely recommended for women younger than age 40?
Mammograms are not routinely recommended for women younger than age 40 because the incidence of breast cancer is low in younger women. Negative effects of screening include persistent anxiety, unnecessary biopsies, and in some cases, unnecessary treatment. Investigators have estimated that 20 to 50 percent of women will have a positive mammogram after 10 years. This proportion would grow if the screening period were extended to include younger women.
6. What is the Breast Imaging Reporting and Database System (BI-RADS®)?
The American College of Radiology (ACR) has established a uniform way for radiologists to describe mammogram findings. The system, called BI-RADS, includes seven standardized categories, or levels. Each BI-RADS category has a follow-up plan associated with it to help radiologists and other physicians appropriately manage a patient's care.
|
Breast Imaging Reporting and Database System (BI-RADS)
|
| Category |
Assessment |
Follow-up |
|
0
|
Need additional imaging evaluation |
Additional imaging needed before a category can be assigned |
|
1
|
Negative |
Continue annual screening mammograms (for women over age 40) |
|
2
|
Benign (noncancerous) finding |
Continue annual screening mammograms (for women over age 40) |
|
3
|
Probably benign |
Receive a 6-month follow-up mammogram |
|
4
|
Suspicious abnormality |
May require biopsy |
|
5
|
Highly suggestive of malignancy (cancer) |
Requires biopsy |
|
6
|
Known biopsy-proven malignancy (cancer) |
Biopsy confirms presence of cancer before treatment begins |
Additional information about BI-RADS is available at the ACR Web site at http://www.acr.org or by calling the ACR at 1-800-ACR-LINE (1-800-227-5463).
7. What happens if a mammogram leads to the detection of ductal carcinoma in situ (DCIS)?
Over the past 30 years, improvements in mammography have made it possible to detect a wide range of breast tissue abnormalities, including DCIS. DCIS is a condition in which abnormal cells are confined to the milk ducts of the breast. The cells have not invaded the surrounding breast tissue. DCIS usually does not cause a lump, so it cannot be detected during a clinical breast exam or BSE. However, mammography is able to detect 80 percent of DCIS cases. Some of these cases will eventually develop into invasive breast cancer.
It is not possible to predict which cases of DCIS will progress to invasive cancer. Therefore, DCIS usually is removed surgically. In the past, DCIS was often treated with a mastectomy, but breast-conserving therapy (breast-sparing surgery plus radiation therapy) is now standard practice for many women with DCIS. Tamoxifen, a drug shown to prevent recurrence of breast cancer, may also be used. Women who have been diagnosed with DCIS should talk with their health care provider to make an informed decision about treatment.
8. What is the cost of a mammogram and cost of subsequent treatment if breast cancer is diagnosed?
The cost of screening mammograms varies by state and by facility, and can depend on insurance coverage. However, most states have laws requiring health insurance companies to reimburse all or part of the cost of screening mammograms. Women are encouraged to contact their mammogram facility or their health insurance company for information about cost and coverage.
9. How can women who are low-income or uninsured obtain a screening mammogram?
Some state and local health programs, as well as employers, provide mammograms free or at low cost. For example, the Centers for Disease Control and Prevention (CDC) coordinates the National Breast and Cervical Cancer Early Detection Program. This program provides screening services and mammograms to low-income, uninsured women throughout the United States and in several U.S. territories. Contact information for local programs is available on the CDC's Web site at http://apps.nccd.cdc.gov/cancercontacts/nbccedp/contacts.asp or by calling the CDC at 1-800-CDC-INFO (1-800-232-4636).
Information about low-cost or free mammography screening programs is also available through NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). Women can check with their local hospital, health department, women's center, or other community groups to find out how to access low-cost or free mammograms.
10. Where can women get high-quality mammograms?
Women can get high-quality mammograms in breast clinics, hospital radiology departments, mobile vans, private radiology offices, and doctors' offices.
The Mammography Quality Standards Act (MQSA) is a Federal law designed to ensure that mammograms are safe and reliable. Through the MQSA, all mammography facilities in the United States must meet stringent quality standards, be accredited by the Food and Drug Administration (FDA), and be inspected annually. The FDA ensures that mammography facilities across the country meet MQSA standards. These standards apply to the following people at the mammography facility:
* The technologist who takes the mammogram.
* The radiologist who interprets the mammogram.
* The medical physicist who tests the mammography equipment.
Women can ask their doctors or staff at the mammography facility about FDA certification before making an appointment. All mammography facilities are required to display their FDA certificate. Women should look for the MQSA certificate at the mammography facility and check its expiration date. MQSA regulations also require mammography facilities to give patients an easy-to-read report on the results of their mammogram.
Information about local FDA-certified mammography facilities is available through the NCI at 1-800-4-CANCER (1-800-422-6237). Also, a list of these facilities is on the FDA's Web site at http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMQSA/mqsa.cfm
11. Should women with breast implants have screening mammograms?
Women with breast implants should continue to have mammograms. (A woman who had an implant following breast cancer surgery should ask her doctor whether a mammogram of the reconstructed breast is necessary.) It is important to inform the mammography facility about breast implants when scheduling a mammogram. The technician and radiologist must be experienced in x-raying patients with breast implants. Implants can hide some breast tissue, making it more difficult for the radiologist to detect an abnormality on the mammogram. If the technician performing the procedure is aware a woman has breast implants, steps can be taken to make sure that as much breast tissue as possible can be seen on the mammogram.
12. What other technologies are being developed for breast cancer screening?
NCI continues to fund research aimed at reducing the already low radiation dose of mammography; enhancing mammogram image quality; developing statistical techniques for computer-assisted interpretation of images; enabling long-distance, electronic image transmission technology (telemammography/teleradiology) for clinical consultations; and improving image-guided techniques to assist with breast biopsies. (A breast biopsy is the removal of cells or tissues to look at under a microscope to check for signs of disease). NCI also supports research on technologies that do not use x-rays, such as magnetic resonance imaging (MRI) and ultrasound to detect breast cancer. The following describes the latest imaging techniques that are in use or being studied, not all of which are being investigated for the screening of breast cancer in average risk women:
-
Ultrasound
Ultrasound, also called sonography, is an imaging technique in which high-frequency sound waves that cannot be heard by humans are bounced off tissues and internal organs. Their echoes produce a picture called a sonogram. Ultrasound imaging of the breast is used to distinguish between solid tumors and fluid-filled cysts. Ultrasound can also be used to evaluate lumps that are hard to see on a mammogram. Sometimes, ultrasound is used as part of other diagnostic procedures, such as fine needle aspiration (also called needle biopsy). Fine needle aspiration is the removal of tissue or fluid with a needle for examination under a microscope to check for signs of disease.
During an ultrasound examination, the clinician spreads a thin coating of lubricating jelly over the area to be imaged to improve conduction of the sound waves. A hand-held device, called a transducer, directs the sound waves through the skin toward specific tissues. As the sound waves are reflected back from the tissues within the breast, the patterns formed by the waves create a two-dimensional image of the breast on a computer.
Ultrasound is not used for routine breast cancer screening because it does not consistently detect certain early signs of cancer such as microcalcifications (tiny deposits of calcium in the breast that cannot be felt but can be seen on a conventional mammogram and may indicate cancer is present) and because it has shown to have a high rate of false positives. A cluster of microcalcifications may indicate that cancer is present.
- Digital Mammography
Digital mammography is a technique for recording x-ray images in computer code instead of on x-ray film. The images are displayed on a computer monitor and can be enhanced (lightened or darkened) before they are printed on film. Images can also be manipulated; the radiologist (a doctor who specializes in creating and interpreting pictures of areas inside the body) can magnify or zoom in on an area. From the patient's perspective, the procedure for a mammogram with a digital system is the same as for conventional mammography.
Digital mammography may have some advantages over conventional mammography. The images can be stored and retrieved electronically, which makes long-distance consultations with other mammography specialists easier. Because the images can be adjusted by the radiologist, subtle differences between tissues may be more easily seen. Digital mammography may reduce the number of follow-up procedures. Digital mammography has been shown to have advantages in women with dense breast tissue, but it is less effective in women with fatty breasts. Overall, digital mammography and conventional mammography are equally effective in finding cancer among women ages 50 and older. Approximately 40 to 50 percent of mammograms nationwide are now done with digital mammography.
-
Computer-Aided Detection
Computer-aided detection (CAD) involves the use of computers to bring suspicious areas on a mammogram to the radiologist's attention. It is used after the radiologist has done the initial review of the mammogram.
In 1998 the FDA approved a breast imaging device that uses CAD technology. Other such devices have been developed and are used in clinical practice. The devices identify suspicious areas and highlight them for the radiologist to review. CAD technology may improve the accuracy of screening mammography. The incorporation of CAD technology to digital mammography is under evaluation.
-
MRI
In magnetic resonance imaging (MRI), a magnet linked to a computer creates detailed pictures of areas inside the body without the use of radiation. Each MRI produces hundreds of images of the breast from side-to-side, top-to-bottom, and front-to-back. The images are then interpreted by a radiologist.
During an MRI of the breast, the patient lies on her stomach on the scanning table. The breast hangs into a depression or hollow in the table, which contains coils that detect the magnetic signal. The table is moved into a tube-like machine that contains the magnet. After an initial series of images has been taken, the patient may be given a contrast agent intravenously (by injection into a vein). The contrast agent is not radioactive; it is sometimes used to improve the visibility of a tumor. Additional images are then taken. The entire imaging session times can vary but typically takes approximately 30 minutes. aggressive tumors than they are in locating tumors that are smaller than eight millimeters and/or less aggressive. PET scans may be helpful in evaluating and staging recurrent disease (cancer that has come back). It is important to distinguish between PET exams of the entire body (used to assess possible disease outside of the breast, such as cancer that has spread to the lymph nodes, liver, lungs, bones or brain) and PET exams under research investigation, which only include the breast and do not provide information from the entire body. These exams, Positron Emission Mammography (PEM), are under research investigation at this time and are not recommended as part of clinical care.
-
Image-Guided Breast Biopsy Techniques
Imaging techniques play an important role in helping doctors perform breast biopsies, especially of abnormal areas that cannot be felt but can be seen on a conventional mammogram or with ultrasound. One type of needle biopsy, the stereotactic-guided biopsy, involves imaging the precise location of the abnormal area in three dimensions using conventional mammography. (Stereotactic refers to the use of a computer and scanning devices to create three-dimensional images.) A needle is then inserted into the breast and a tissue sample is obtained. Additional samples can be obtained by moving the needle within the abnormal area. Needle biopsy can also be performed with ultrasound guidance and with MRI guidance. A variety of needle types can be used, from very small needles (fine needle aspiration, or FNA) to larger needles or a needle biopsy device that uses vacuum assistance to sample tissue.
|
Medical News 
Comments
—
RSS feed for comments to this post.