Techniques under study for use in diagnosing breast cancer include:
These tools may provide more information about tumors that can help guide treatment.
Breast magnetic resonance imaging (MRI)
There is a growing interest in breast magnetic resonance imaging (MRI) as a tool to detect and diagnose breast cancer. Breast MRI uses magnetic fields to create high quality images that in some cases may be better than mammograms and ultrasound images.
For more on breast MRI and breast cancer screening, see the Early Detection section.
Breast MRI for diagnosis
Breast MRI may help diagnose breast cancer in certain cases. For women with hard-to-find (occult) breast cancers who have cancer in the lymph nodes or metastases at diagnosis, MRI may help find the original tumor in the breast . And, in some cases, MRI may help find breast cancer recurrence and guide needle biopsies .
Other uses for breast MRI under study include distinguishing cancerous breast lumps from benign (non-cancerous) ones and checking whether cancer has spread to the lymph nodes in the underarm (axillary nodes) [73-74].
Breast MRI for surgical planning
An increasingly common, but controversial use of breast MRI is as a tool to help decide whether a woman should have mastectomy or lumpectomy. Breast MRI can find small tumors in the breast that may be missed by a mammogram. Some health care providers use breast MRI to see how widely the cancer appears to be spread throughout the breast. Study findings have shown that women who have breast MRI before surgery are more likely to choose mastectomy over lumpectomy plus radiation therapy [75-77]. Based on the breast MRI images, they decide mastectomy is a better option than lumpectomy.
A major concern about using breast MRI in this way is that it's not clear if the small masses that an MRI finds are better treated with mastectomy or with lumpectomy plus radiation [73,115]. A recent meta-analysis that combined the results of four studies showed that using breast MRI before surgery to make treatment decisions did not lower the risk of breast cancer recurrence . This means women chose mastectomy over lumpectomy based on breast MRI results when lumpectomy would have been an equally good option.
This topic is still under study. Talk to your provider if you have any questions about the benefits and risks of using breast MRI for planning treatment.
Breast tomosynthesis (3D digital mammography)
Special imaging machines can take multiple, standard two-dimensional (2D) digital mammograms. Computer software combines the 2D X-ray images into a three-dimensional (3D) image (called breast tomosynthesis). A breast tomosynthesis machine provides both a regular digital mammogram and an enhanced 3D image based on the 2D images.
Breast tomosynthesis is under study for use in breast cancer diagnosis [78-79]. One study found digital mammography plus breast tomosynthesis was better at diagnosing breast cancer than digital mammography alone . However, breast tomosynthesis is still under study for use in diagnosis. Because breast tomosynthesis requires a special machine and radiologists must have special training to read the images, it is not widely available at this time.
Learn about the use of breast tomosynthesis in breast cancer screening.
Positron emission tomography (PET)
Positron emission tomography (PET) is a test that shows how much sugar is consumed by cells. With PET, a radioactive sugar is injected into the body. The sugar builds up more in cancer cells and can be detected by a special camera that images the cells. PET is used to find metastases (cancer that has spread beyond the breast to other organs, such as the bones, lungs, liver and brain).
PET is under study for breast cancer diagnosis and finding cancer that has spread to the lymph nodes in the armpit (axillary nodes). However, early findings suggest it cannot give a detailed enough image to make it a good tool for this task .
Visit the Society of Nuclear Medicine's discoverMI.org website for more information on PET.
Every cell in your body has genes that contain the blueprints (genetic code) for your body. Similarly, every cell in a breast tumor has genes. These genes contain the blueprints for the tumor.
Tumor profiling tests (using gene expression profiling tools) give information about the genes in cancer cells. These tests allow researchers to study thousands of these genes at one time. Specific genes (or combinations of genes) may give useful information about prognosis and may help make treatment decisions [82-83]. The gene profiles of some tumors may help predict whether the cancer is more likely to recur (when cancer comes back) and metastasize (when cancer spreads to other organs) . Tumors with gene profiles showing a high risk of breast cancer recurrence or metastasis may be more likely to respond to chemotherapy than tumors with gene profiles showing a low risk.
Oncotype Dx® is the only tumor profiling tool widely used in the U.S. It tests a sample of the tumor (removed during a biopsy or surgery) and looks at a set of 21 genes. Oncotype Dx can be used to help make chemotherapy treatment decisions in some people with estrogen receptor-positive cancers who are going to have hormone therapy . At this time, other tools are mostly limited to the research setting. At this time, other tools are mostly limited to the research setting. Researchers are working to address the technical limits of these tools.
Learn more about Oncotype Dx.
MammaPrint® is a tumor profiling test that looks at a set of 70 genes to give prognostic information for lymph node-negative breast cancers.
MammaPrint is not widely used in the U.S. It is more commonly used in Europe.
PAM50 (Prediction Analysis of Microarray 50) is a promising, new tumor profiling test that looks at a set of 50 genes to determine the molecular subtype of breast cancer (learn more). This set of genes may give more information than other tests to help identity which of these cancers have the highest risk of breast cancer recurrence and may get the most benefit from chemotherapy [84-85].
Subtypes of breast cancer
There is a growing interest in learning how molecular and genetic differences among breast cancers relate to prognosis and treatment. Understanding these differences may help predict how a person's cancer will respond to a certain treatment.
Most studies divide breast cancer into four major molecular subtypes:
- Luminal A
- Luminal B
- Basal-like/triple negative
- HER2 type
At this time, molecular subtypes are used mostly in research settings and are not included in pathology reports (learn more). Prognosis and treatment decisions are guided by tumor stage, hormone receptor status and HER2/neu status.
Learn more about the subtypes of breast cancer.
Circulating tumor cells and circulating tumor DNA
Many studies have shown circulating tumor cell levels can help predict survival time for people diagnosed with metastatic breast cancer [86-91]. The more circulating tumor cells in the blood, the more advanced metastatic breast cancer is likely to be. Having more of these cells may also predict a lack of response to treatment. Similarly, circulating tumor DNA is under study for use in monitoring metastatic breast cancer and predicting treatment response in metastatic cancers .
At this time, circulating tumor cell and circulating tumor DNA testing are not routinely done in clinical practice. It is still not known how much more information these tests provide over standard tests and tumor markers in guiding the treatment of metastatic breast cancer . However, a large clinical trial is studying how best to use circulating tumor cell test results to improve chemotherapy choices for metastatic breast cancer.
Circulating tumor cells may also help predict disease-free survival time in women with early breast cancer, but study findings are mixed [94-97].
Learn about the latest research on circulating tumor cells that Komen is funding in the January 2014 Science Buzz.