Breast Cancer Screening
Sherri H. Chafin, M.D. reads digital images of mammograms at St.Clair Hospital.
Sherri H. Chafin, M.D., vice chairman, Department of Medical Imaging/ Director of Breast Imaging, St. Clair Hospital discusses the importance of breast cancer screening.
Q: October is National Breast Cancer Awareness Month. Why is it so important for women to be keenly aware of the importance of being screened for breast cancer, and knowing the signs, symptoms and treatments?
Dr. Chafin: Depending on the location of the breast cancer and the patient’s breast size, a breast cancer may not be palpable. So annual screening does allow us to look for changes that might not be detected on a physical exam. Patients should also be aware that there are two types of mammogram procedures. The screening mammogram is for patients who are asymptomatic. A diagnostic mammogram should be ordered for patients with symptoms or for follow-up of prior findings.
Q: At what age should a woman have her first mammogram? And how often after that?
Dr. Chafin: The current recommendation from the American College of Radiology is first mammogram at age 40 and then annual surveillance. If you have a mother with breast cancer, it is recommended that you begin your surveillance 10 years before the age of diagnosis, or at age 40, whichever is earliest. The American Cancer Society also recommends an annual MRI for those patients who are considered high risk.
Of course, Breast Cancer Awareness Month is a great opportunity to discuss breast density, which is the ratio of glandular and connective breast tissue to fatty breast tissue. This reflects the breast composition and relative amount of glandular tissue, connective tissue, and fat. Fat tissue appears dark on a mammogram and dense tissue appears white. Breast cancer masses have a similar density to glandular tissue. So on a mammogram, if you have a lot of dense tissue it might mask a breast cancer. I sometimes explain this with the following analogy: It is difficult to find a polar bear on a glacier and near impossible in a blizzard. If a patient has a lot of dense tissue it will show as white areas on a mammogram. We often use supplemental mammogram views and ultrasound to get a better picture. Sometimes we even use MRI. Most of our recall patients are imaged to clarify densities on a mammogram.
Q: What barriers keep women from getting mammograms on a routine basis?
Dr. Chafin: Most recently, radiation fear has kept some women from mammograms. The dose of radiation is measured in millisieverts (mSv). The average person in the U.S. receives an effective dose of about 3 mSv per year from naturally occurring radioactive materials and cosmic radiation from outer space. These natural "background" doses vary throughout the country. To put this in perspective, for a standard mammogram, the dose is 0.4 mSv. This is roughly the dose you'd receive from your normal environment over a period of 7 to 8 weeks. An X-ray of the spine is 1.5 mSv, equal to 8 months of background radiation. A CT of the chest is 7 msV, equal to 2 years of background radiation. The risk of a mammogram causing cancer is very low.
For more information about St. Clair Hospital's mammography services or to schedule an appointment, click here.