Breast Cancer: The Complete Guide
By Yashar Hirshaut, M.D., FACP, Peter I. Pressman, M.D., FACS
Is a Mammogram Dangerous?
If there is something suspicious in your breast, the crucial thing is to find out what, if anything, is wrong. There is no significant radiation risk from investigative mammograms.
This question does arise, however, when we are considering this procedure for annual screening purposes. In that case, the most important reservation people have about mammography has to do with its safety. What is the risk that the exposure to radiation during the procedure-and from repeated mammograms over the years-will itself cause cancer?
The risk has been greatly reduced in recent years as mammography techniques have been improved. Much less exposure is now required than in the past. Strict guidelines are in place for the use of mammography equipment.
Still, you can't reduce the risk to zero. Anyone who tells you there is no risk is oversimplifying. Nevertheless, it is clear that at this time the benefits of mammography far outweigh its possible problems. There are several compelling reasons for this belief:
Mammography is at this time the best screening tool we have to detect very early cancers. MRI can be more sensitive, but used alone it has not yet been shown to be as valuable as mammography for screening purposes.
The probability of danger from radiation seems to be a great deal smaller than the probability of danger from an undetected cancer.
The breast tissue of women in their teens and early twenties is more sensitive to low-level radiation than it is when they get older. For this reason, unless there are especially suspicious circumstances, we advise women under thirty-five not to have routine screening mammograms.
Conversely, we feel fairly confident that the radiation risk to women over thirty-five is very, very small.
At the moment, there are no known problems from high-quality mammography, and it does seem to be doing a good job.
Why Is Mammography Important?
Mammography is essential as a diagnostic tool if there is any abnormality of the breast. It is also the only proven screening tool for finding early cancers in seemingly healthy women.
When an annual mammogram is combined with physical examination by a doctor, there is more than a one-third reduction in mortality from breast cancer. We have established this figure on the basis of an over-forty-five-year ongoing randomized study of the incidence of breast cancer among a population of about 62,000 women, some of whom had regular mammograms and physical exams and others of whom did not. The data from this screening project by the Health Insurance Plan (HIP) of Greater New York have been confirmed in a variety of ways in other studies in the United States, Sweden, Holland, Denmark, and England.
When we combine mammography with professional physical examination and self-examination, we have a powerful early-warning system against breast cancer. And the earlier that cancers are found, the better the chance for survival and for breast preservation.
There may yet be another way to add to our ability to detect breast cancer early. As technology improves, sonography is beginning to supplement the benefits of mammography. Also called ultrasound (and used during pregnancy to view the fetus), sonography uses high-frequency sound waves to examine the breast. A small amount of gel is applied to the breast and an instrument called a transducer is moved across its surface. The transducer emits short pulses that either pass through the tissue or-if the tissue is solid-bounce back. The results of this sound wave interaction are recorded on a screen and photographed. No radiation is used.
Because it cannot find microcalcifications or provide an overall picture of the breast, and because its findings are not always reproducible, sonography has not been considered a good general screening tool. However, new, better-designed sonography machines and better-trained radiologists have significantly improved the quality of sonograms in recent years. Using the sonogram for guidance, experienced radiologists can readily biopsy suspicious areas found during physical examination, mammography, and sonography. I he result of these advances is that more women, particularly younger women with dense breasts, are having sonograms at the same intervals as mammography. The technique is very useful for studying a specific density that was previously seen on a mammogram or MRI, or a lump that has been felt but is not seen on X-ray. If the density is a liquid-filled cyst, the sound waves will go through it. If it is a solid mass-a fibroadenoma or a cancer-the sound waves will bounce back.
Increasingly, sonography is being employed to complement mammography for the screening of apparently normal women for breast cancer. While the guidelines for mammography have received a great deal of consideration and are by now fairly well-established, there are no universally accepted guidelines for sonography.
The following reflects my own views on when sonography is indicated:
1. When lumps that are felt on breast examination are not seen on a mammogram. Sonography is used to investigate their nature.
2. When densities are seen on mammography. Sonography can disclose whether they are benign cysts, which may be allowed to remain, or solid tumors, which might need to be biopsied.
3. As a monitoring procedure for women who have multiple breast cysts.
4. When a patient's breast tissue is extremely dense on mammography, as in young women, and there is concern that a tumor may be missed.
5. To investigate or biopsy an abnormality seen on MRI.
6. In the follow-up of women who have had breast cancer, as an additional way to find small cancers. Sonography can also be added between annual mammograms as an independent annual screening procedure.
Where Do I Go For A Sonogram?
Radiologists who specialize in mammography are often skilled in sonography as well and can discuss whether it would be a useful procedure for you. It does add expense, and may almost double the cost of the visit.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is an imaging method that is routinely used to diagnose conditions in other parts of the body. It is increasingly being used in conjunction with mammography for the diagnosis of breast cancer. An MRI image is created with the use of a magnetic field rather than with radiation. Before the procedure a contrast material, gandolinium, will be injected into a vein. You will then be placed in a face-down (prone) position with both breasts hanging through an opening in a specialized table. Very little breast compression is needed for this study. An MRI identifies tumors by locating their increased blood supply. MRI of the breast has been found useful in the following circumstances:
1. To determine the extent of cancer in a breast where a newly diagnosed cancer has already been detected by mammography, and in order to see whether the tumor can be safely removed by lumpectomy and a mastectomy can be avoided. It is also a useful way to make certain that there are no areas of concern in the other breast.
2. To search for the source of breast cancer in women who have developed enlarged axillary lymph nodes that on testing prove to contain cancer. If physical examination, mammography, and sonography are all negative, an MRI may be able to detect a hidden tumor in the breast.
3. To preoperatively search for an unsuspected cancer when a prophylactic mastectomy is planned.
4. In women who have breast implants, particularly those filled with liquid silicone, to determine whether the implants remain intact or are leaking.
5. For screening the breasts of women who are known or suspected to have mutations of the BRCA1-2 genes.
6. For screening the breasts of women who have a strong family history of breast cancer but are not known to be carriers of a recognized mutation.
MRI of the breast is more sensitive than a regular mammogram but is not used in routine screening because it may show many abnormalities which-while they are not likely to represent cancer-must be biopsied to make certain this is the case. These are known as false positives. Suspicious areas are biopsied by core needle biopsy techniques similar to those described on page 79. They may be performed using ultrasound or MRI as a guide.