Breast Cancer Screening Tests
Breast cancer screening can involve a number of different types of examinations, which include breast self examination (BSE), clinical breast examination (CBE), mammography, magnetic resonance imaging (MRI), and ultrasound.
Breast Self-Examination
During a breast self-examination (BSE), a women checks her own breasts for any irregularities, which may include lumps, changes in breast size or shape, nipple discharge, or irregular tissue thickening. Despite attempts by investigators to demonstrate the impact of BSE on reducing breast cancer deaths, no study has been able to show a statistically significant reduction. As a result, our doctors and a number of national organizations no longer aggressively encourage women to perform BSE. However, because BSE is easy and free, and may detect some cancers, women are not discouraged from performing regular BSE.
Clinical Breast Examination
A clinical breast examination (CBE) is a physical examination of the breast performed by a health professional. In clinical studies where CBE was performed along with mammography, the reduction in deaths from breast cancer was similar to the reduction in those women who had received mammography alone. This suggests that CBE adds little to mammography in reducing breast cancer deaths.
Mammography
Mammography is the diagnostic examination of the breast using low-dose x-rays. Annual mammogram screenings have been shown to reduce significantly the number of women dying from breast cancer in the age group 40 years and older. Until fairly recently, all mammograms used the conventional film-based technique, which utilizes x-rays to produce an image of the breast on film. Introduced in the US in 2001, digital mammography also uses x-rays but captures the image on a computer, where it can be viewed and manipulated for contrast. While finding no significant difference between the two techniques when applied to the general population and for most women over 50, studies have shown that digital mammograms detected more tumors in three specific groups: women under 50, women with dense breasts, and women not yet in menopause.
Ultrasound
Ultrasound, also known as ultrasonography, is an imaging method in which high-frequency sound waves are used to create images of blood vessels, tissues, and organs including the breast. Breast ultrasound is often used to evaluate breast abnormalities that are found during mammography or a clinical breast exam. The accuracy of breast ultrasound is highly dependent on the skill level and training of the ultrasound technician. This creates an increased risk of false positives, requiring follow-up exams and biopsy -- which can be expensive and lead to unnecessary anxiety for the patient.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a diagnostic procedure that uses a magnetic field to provide three-dimensional images of internal body structures, including the breast. MRI is expensive and requires the injection of intravenous contrast dyes. Recent studies of women with an inherited risk of breast cancer have shown that MRI has a higher sensitivity in detecting breast cancers than other screening methods. However, there are no study data showing that MRI screening reduces the number of breast cancer deaths.