Techniques under study for use in diagnosing breast cancer include:
These tools may provide more information about tumors that can help guide treatment.
Magnetic resonance imaging (MRI)
There is a growing interest in magnetic resonance imaging (MRI) as a tool to detect and diagnose breast cancer. MRI uses magnetic fields to create high quality images that in some cases may be better than mammograms and ultrasound images.
For more on MRI and breast cancer screening, see the Early Detection section.
MRI for diagnosis
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 be help find recurrence and guide needle biopsies .
Other uses for 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 armpit (axillary nodes) [65-66].
MRI for surgical planning
An increasingly common, but controversial use of MRI is as a tool to help decide whether a woman should have mastectomy or lumpectomy. MRI can find small tumors in the breast that may be missed by a mammogram. Some health care providers use MRI to see how widely the cancer appears to be spread throughout the breast. Based on the MRI images, they may decide mastectomy is a better option than lumpectomy.
A major concern about using 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 . This means women may choose mastectomy over lumpectomy based on MRI results when lumpectomy would be an equally good option. Further research will help shed light on this issue.
Until results from studies are available, talk to your provider if you have any questions about the benefits and risks of using MRI for planning treatment.
3D digital mammography (breast tomosynthesis)
Advances in digital mammography machines and software can create a three dimensional (3D) X-ray image of the breast. The machine takes multiple two dimensional (2D) X-ray images. Computer software combines the 2D images into one 3D image [67-69].
One study found digital mammography plus 3D mammography was better at diagnosing breast cancer than digital mammography alone . However, 3D mammography is still under study and it is not known if it is better than standard mammography. Because 3D mammography requires a special machine, it is not widely available.
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 and liver).
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.
Gene expression profiling
Gene expression profiling is a tool that lets researchers study thousands of genes at one time. Studying which genes are active (expressed) and which are inactive in different types of tumor cells may help researchers to develop more targeted treatments. This tool also may allow researchers to compare gene expression in treated versus untreated tumor cells to learn how certain treatments affect tumors [71-72].
Oncotype Dx® is a gene expression profiling tool currently in use. (Learn more about Oncotype Dx.) At this time, other tools are mostly limited to the research setting. Researchers are working to address the technical limits of these tools.
MammaPrint® is a gene expression profiling tool for lymph node-negative breast cancer (it can be used for either hormone receptor-positive or hormone receptor-negative tumors).
MammaPrint is mostly limited to the research setting in the U.S. because it requires special preparation of the biopsy tissue. It is more commonly used in Europe.
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.
One theory divides 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
Many studies have shown circulating tumor cell levels can help predict survival time for people diagnosed with metastatic breast cancer [73-78]. 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.
At this time, circulating tumor cell testing is 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 [80-83].