A number of tools for finding breast cancer early are under study. These include magnetic resonance imaging (MRI), ultrasound, molecular breast imaging (MBI), positron emission tomography (PET) and thermography. At this time, it is not clear if these tools will play a role in screening for women at average risk of breast cancer.
If you are interested in joining a clinical trial studying one of these screening methods, talk to your health care provider. For more information on clinical trials, see the Treatment section.
Current diagnostic tools under study for use in screening
Magnetic resonance imaging (MRI)
MRI uses magnetic fields to create an image of the breast. There is growing evidence that it is a good tool for breast cancer screening used together with mammography in certain groups of women at higher risk [47-50]. (Learn more about MRI as a screening tool for women at higher risk.) However, it is not clear that MRI offers a similar benefit for women at average risk.
Screening MRI has some drawbacks compared to standard mammography. MRI is more invasive than standard mammography because a contrast agent must be injected before the procedure. It is also expensive and not always covered by insurance. Further, MRI results in more false positives reports than standard mammography. And, not every center doing MRI has the proper equipment for making good images of the breast or the radiologists trained to read them [25].
Recent findings suggest that for women diagnosed with cancer in one breast, MRI with mammography can find breast cancer in the opposite breast better than mammography alone [51].
Learn more about MRI and the diagnosis of breast cancer.
Ultrasound
Ultrasound uses sound waves to make images of tissue. It is often used as a follow-up test to an abnormal mammogram or clinical breast exam. Studies show that ultrasound alone is not a good breast cancer screening tool [24,52-54]. It does not give an accurate image of the breast, which can lead to false positive and false negative results. Also, the quality of the image can vary greatly depending on the skill and experience of the person doing the ultrasound. Each of these factors is a limitation when it comes to screening.
Ultrasound is better than mammography at distinguishing dense breast tissue from tumors. For this reason, ultrasound combined with mammography may be helpful in screening some women with dense breasts [26,50-53]. The American College of Radiology Imaging Network’s multi-center trial found that ultrasound plus mammography increased screening accuracy compared to mammography alone in women at higher risk of breast cancer and women with dense breast tissue [54]. As found in prior studies, though, the number of false positives was also increased. There does not appear to be added benefit of using ultrasound for women who screened with MRI along with mammography. However, ultrasound may be a useful addition to screening mammography among women at higher risk of breast cancer for whom MRI is not yet recommended [54]. Ultrasound is less expensive and less invasive than MRI. More research on the benefits of ultrasound in combination with mammography is needed before recommendations can be made on its use for screening women at average to higher risk of breast cancer.
Other screening tools under study
Molecular breast imaging
Molecular breast imaging uses a short-term radioactive agent that is injected and absorbed into the breast and recorded by a special camera. Breast cancer cells appear to absorb more of the agent than healthy cells. Molecular breast imaging is being studied as a breast cancer screening tool combined with mammography among women with dense breasts [55]. Currently, it is only used as part of a clinical trial and its role in breast cancer screening is not yet clear. For more on clinical trials, visit the Treatment section.
Positron emission tomography (PET)
Positron emission tomography (PET) is based on the idea that cancer cells absorb sugar more quickly than other cells. This technique involves injecting a radioactive sugar into the body. Sugar will build up more in cancer cells and can be detected by the PET scanner. Positron emission tomography (PET) is a test that detects how much sugar is consumed by cells. Cancer cells tend to consume more sugar than normal tissue and this can help identify tumors. Despite some benefit as a tool for finding distant metastases (for more on this, see the Diagnosis section), PET cannot provide a detailed enough image to find early stage breast cancers [56,57]. Therefore, it is not yet a useful tool for breast cancer screening.
Thermography
Thermography was used in breast cancer screening and diagnosis until the 1980s, when mammography was shown to be a more accurate tool [25]. The test uses infrared light to measure temperature differences on the surface of the breast. Abnormal temperature patterns can signal a problem in the breast. However, many benign conditions also cause abnormal heat patterns, and thermography cannot distinguish between benign and cancerous patterns [25]. Also, because thermography measures heat at the surface of the breast, it is not good at finding cancers deeper within the breast tissue. Although future improvements in thermography may make it a useful tool in staging or diagnosis, it has limited ability as a screening tool [25,58].
Updated 10/05/09
