Breast Cancer Screening
The ultimate goal of widespread screening for breast cancer is a reduction in mortality from the disease. Toward this end, appropriate screening for breast cancer involves both the physician and the patient. In general, the approach should include a clinical exam by a healthcare provider, monthly breast self-examinations by the patient, and routine screening mammography.
Schedules for both clinician examinations and mammography will vary depending on the risk of an individual woman.
The data regarding the impact of breast self-examination on mortality from breast cancer are inconsistent. While many retrospective studies have indicated earlier stage of diagnosis and a reduction in the risk of mortality in women who perform routine monthly self-examinations, the only randomized trial addressing breast self-examination has not been able to demonstrate an impact upon stage of diagnosis. Because of these contradictory findings, further research is warranted. It is, however, still appropriate for women in all risk categories to practice self-examination. Not only does this have a potential impact upon stage at diagnosis, it allows the woman to be involved in her own medical care.
In addition to practicing monthly breast self-examination, all women over the age of 20 should have a clinical breast examination by a healthcare provider at least yearly. In most instances, women who have a normal risk for breast cancer development can be seen by their gynecologist or internist for this examination. Some women with normal risk may be referred to a breast specialist, however, simply because of difficulty with examinations.
This occurs almost exclusively in women who have extremely dense, fibrocystic breast tissue.
Women who are at moderately increased risk of breast cancer (less than two times the normal risk of breast cancer development) may benefit from seeing a clinician more often. While no data exist to indicate that more frequent examinations will have a significant impact upon breast cancer mortality, studies have documented the ability of trained professionals to detect breast lesions and subtle skin and nipple changes at an earlier point than those who do not specialize in this area.
A family history consistent with a hereditary breast cancer syndrome, the presence of a BRCA1 or BRCA2 mutation or the presence of atypical hyperplasia or LCIS places a woman in the highest risk category. In this population, consideration of more frequent examinations should always be entertained. Often, these women will be examined by a healthcare provider two to four times per year. These examinations allow for the detection of early lesions that may present between mammographic studies. It is especially useful in the very young patient, in whom mammographic screening is sometimes less helpful due to the density of breast tissue.
Mammography continues to be the most significant component of breast cancer screening for the majority of the population. Every study that has evaluated this modality has demonstrated a reduction in mortality from breast cancer with yearly screening exams in women over the age of 50. Although it is somewhat more difficult to demonstrate a statistically significant impact upon breast cancer mortality when routine mammography is employed in women between the ages of 40 and 50, there is a trend toward a decrease in mortality in this age group. Therefore, women in all risk categories should begin yearly mammographic screening at the age of 40.
For women at increased risk for breast cancer development, it may be appropriate to begin mammographic screening at an earlier age. A study performed at Memorial Sloan-Kettering Cancer Center demonstrated a downward shift of 8-10 years in the age of diagnosis of breast cancers in consecutive generations of women in the same family. While earlier diagnosis had a small impact upon this, it was not the only factor. Thus, it is appropriate for women with family histories of breast cancer to begin mammographic screening 10 years earlier than the age at which the youngest family member developed breast cancer or at the age of 25, whichever is later. Once screening has been initiated, it is appropriate to perform exams yearly unless a woman is pregnant or breast-feeding.
Newer imaging techniques for screening are currently being studied in the high-risk population. The hope is that they will provide additional information that mammography is currently unable to provide. Whether ultrasound or magnetic resonance imaging on a routine basis will be beneficial in this population remains to be determined.
Alexandra S. Heerdt
Breast cancer detection demonstration project: five-year summary report. CA 2003
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