PAM50 (Prosigna®) is a tumor profiling test that helps show whether some estrogen receptor-positive (ER-positive), HER2-negative breast cancers are likely to metastasize (when breast cancer spreads to other organs).
Tumor profiling
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 cancer.
Tumor profiling (using gene expression profiling tools) gives information about the genes in cancer cells. You may also hear the terms genomic testing and molecular profiling.
Prosigna is a tumor profiling test.
PAM50 (Prosigna) testing
PAM50 stands for Prediction Analysis of Microarray 50. It tests a sample of the tumor (removed during a biopsy or surgery) for a group of 50 genes.
The results of the PAM50 (Prosigna) test help predict the chance of metastasis.
PAM50 (Prosigna) scores
If the Prosigna test shows the breast cancer has a fairly high risk of metastasis (the PAM50 score is high), a more aggressive treatment plan that includes both hormone therapy and chemotherapy may be advised [50,52-53].
If the test shows a low risk of metastasis (the PAM50 score is low), the use of hormone therapy alone may be considered [50,52-53]. In this way, Prosigna may help some people avoid chemotherapy and its side effects.
When can PAM50 (Prosigna) be used?
PAM50 (Prosigna) helps predict the chance of metastasis for postmenopausal women with breast cancers that are all of the following [50,52-53]:
- Tumor size no larger than 5 cm
- ER-positive (and will be treated with hormone therapy)
- HER2-negative
- Lymph node-negative
Under study
Some findings show PAM50 (Prosigna) may help identify which ER-positive breast cancers may benefit from hormone therapy beyond 5 years [54].
However, at this time, Prosigna is not recommended for use in guiding whether or not a person should take hormone therapy for longer than 5 years [53].