Breast cancer is the most common cancer in women. Our risk increases as we age, with 1 in 8 women being diagnosed with breast cancer by the time they are 80. It is recommended that women undergo screening that can look for possible cancer in the breast so that, if disease is present, it can be found before the development of symptoms, such as a lump that can be felt. Early detection improves breast cancer survival.
Mammography was the original test developed to screen for breast cancer. Both digital mammography (images on digital monitors) and film-screen mammography (images on specialized x-ray film) involve taking images of the breasts as they are compressed between two metal plates. Most imaging centers in the United States now use digital mammography; however, film-screen mammography is still in use in some facilities.
An advantage of digital mammography is that the radiologist is to able fine-tune the images to get a detailed look at the breast tissue without exposing the patient to additional radiation. In film screen mammography, “what you see is what you get.” Mammography remains the best screening test for breast cancer, with other tests being used to add detail or clarify what is seen on mammogram.
Ultrasound of the breast is often done in addition to mammogram to further evaluate nodules and densities seen on mammogram. It is also used for women who have a lump that can be felt, nipple discharge, or localized breast pain. Ultrasound can be very helpful when a patient has dense breast tissue that can hide a lump on mammogram. Because ultrasound detects differences in breast tissue density, it may show a mass even in dense breast tissue. Ultrasound does not replace mammography for screening of breast cancer but may be used along with mammography in women with very dense breast tissue.
Breast MRI is a sensitive test that is generally reserved for patients at high risk for breast cancer or for patients who have been diagnosed with breast cancer. The test is sensitive enough to detect very small lumps in the breast but is not able to determine which small lumps are cancerous and which are not. Therefore, MRI leads to more biopsies. For high-risk women, such as BRCA gene carriers, or for women already diagnosed with breast cancer, the ability of breast MRI to find very small or additional cancers can change a woman’s breast cancer treatment plan.
Digital Breast Tomosynthesis
Digital breast tomosynthesis is a new technology that is providing improved imaging of the breast. The limitation of standard mammography is the potential for overlap of breast tissue. The overlapping tissue can hide a lump and the mammogram might be read as normal. Digital breast tomosynthesis addresses this overlap issue by taking multiple pictures very close together. The pictures are then converted to a 3-D image that decreases the overlap effect. Several studies have shown better visibility of breast cancers with the use of digital breast tomosynthesis. At the very least, it has been shown to reduce the need for additional mammographic images to assess questionable problem areas. This technology, which is becoming more widely available, can also be helpful in screening women with dense breast tissue.
No test is 100% accurate, but used together they can provide the best image of breast tissue. Talk to your doctor about any concerns you may have regarding your breast exam or risk factors for breast cancer.