Use of Multi-Gene Expression Assays for Breast Cancer
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Breast cancer is a complex disease that requires accurate diagnosis and treatment. Multi-gene expression assays have had a significant impact on the way breast cancer is managed by enabling more precise and individualized treatment strategies. This article will discuss commonly used multi-gene expression assays, their significance and their utility.
A breast cancer gene expression assay is a diagnostic test used to analyze a breast cancer’s gene expression profile.
What is the utility of multi-gene expression assays in breast cancer?
Besides the hormone receptors (ER and PR) and HER2, there are various oncogenes (cancer-causing genes) that have been known to play different roles in breast cancer. Multi-gene expression assays analyze the level of different oncogenes to predict the aggressiveness of the disease as evidenced by the following:
- The growth rate of cancer cells
- The likelihood of cancer cells spreading
- The likelihood of the cancer recurring
Multi-gene expression tests examine oncogenes or biomarkers in breast cancer tissue to predict the risk of cancer coming back (recurrence). Some of these assays, like Oncotype DX, provide additional information on the benefit of chemotherapy or other systemic therapy (adjuvant therapy) in preventing recurrence after operation. This can help oncologists determine if adjuvant therapy should be given, sparing patients from unnecessary treatments and their side effects if they have a low risk of recurrent breast cancer.
Commonly used multi-gene expression assays
Currently, the most commonly used multi-gene expression assays are:
- Oncotype DX®
- MammaPrint®
- Prosigna® (PAM50)
- Breast Cancer Index™
- EndoPredict®
Below is a summary of five commonly used multi-gene expression assays and the types of breast cancer they're recommended for.
Oncotype DX® | MammaPrint® | Prosigna® | Breast Cancer IndexTM | EndoPredict® |
|---|---|---|---|---|
Stage I-IIIa, ER+, HER2- | Stage I-II, Any status of hormone receptor, any HER2 status, tumor size ≤5cm, 0-3 nodes | Stage I/II (node-), Stage II (0-3 nodes), ER+ and PR+, HER2- | Stage I/II (node-), Stage I-III (0-3 nodes), ER+ and PR+ | Stage I/II, ER+, HER2-, 0-3 nodes |
Different multi-gene expression assays have different benefits and limitations as summarised below.
Oncotype DX® | MammaPrint® | Prosigna® | Breast Cancer IndexTM | EndoPredict® | |
|---|---|---|---|---|---|
Measures recurrence risk | Yes | 5 years post-diagnosis | Yes | 5 years post-diagnosis | 10 years post-diagnosis |
Measures absolute benefit from chemotherapy | Yes | - | Yes | - | Yes |
Measures distant recurrence risk | Yes, up to 9 years when treated with hormone therapy alone for 5 years | - | Yes, up to 10 years | Yes, up to 10 years after hormone therapy or chemotherapy | Up to 15 years after hormone therapy for 5 years |
Additional measurements | - | Risk of metastasis | Intrinsic subtype | - | - |
Table data source: E. Güler (2017) and manufacturers' websites
The results of these assays are typically integrated with clinical and pathological information to provide a comprehensive picture of the patient's disease and aid in treatment decision-making. Patients are now able to receive treatments tailored to their specific tumor characteristics, potentially leading to better outcomes and reduced side effects.
