The 21-gene recurrence score is a genomic test that examines the activity of specific genes within a tumor. This analysis helps oncologists and patients make informed decisions about the treatment plan following surgery. The test provides personalized information to guide this process.
Purpose of the Recurrence Score Test
This genomic test is designed for individuals with early-stage, hormone receptor-positive (HR+), and HER2-negative invasive breast cancer. The test serves a dual function by providing both prognostic and predictive information for treatment planning.
The prognostic aspect of the test estimates the likelihood that the cancer might return, or recur, in a distant part of the body. By analyzing a panel of 21 genes within the tumor tissue, the test gauges the cancer’s aggressiveness, providing a clearer picture of the individual’s ten-year recurrence risk.
The test’s predictive capability helps determine if a patient is likely to benefit from adding chemotherapy to their hormone therapy. By examining the tumor’s genetic makeup, the test identifies which individuals have a cancer biology that is responsive to chemotherapy. This allows for more tailored treatment recommendations.
For some patients, the results indicate that hormone therapy alone is sufficient, allowing them to avoid chemotherapy’s side effects. For others, the results show that adding chemotherapy provides a significant benefit in reducing the risk of recurrence.
Understanding the Score Results
The outcome of the 21-gene test is a numerical Recurrence Score ranging from 0 to 100. This score is calculated from the expression levels of the 21 genes analyzed in the tumor sample. The number corresponds to the risk of cancer returning and reflects the tumor’s biological characteristics.
Scores are grouped into categories that correlate with the risk of distant recurrence. A low score, often in the 0-25 range depending on other factors, indicates a lower risk of the cancer returning and a less aggressive tumor biology.
A high score points to a more aggressive cancer biology and a higher statistical probability of recurrence. This score provides a more nuanced understanding of risk compared to traditional pathological features alone.
An intermediate score falls between the low and high-risk categories, reflecting a moderate level of aggressiveness. Because the risk is neither clearly low nor high, other factors are often considered alongside the score to make a final treatment decision.
How the Score Influences Treatment Decisions
The Recurrence Score directly impacts the decision to use chemotherapy with hormone therapy. It quantifies the potential benefit of chemotherapy, facilitating a detailed conversation between the patient and oncologist. A low score suggests hormone therapy alone is effective, as chemotherapy’s side effects would likely outweigh its minimal benefit.
Evidence from clinical trials established the guidelines for using the Recurrence Score. The TAILORx (Trial Assigning IndividuaLized Options for Treatment) study was a significant trial for patients with scores in the low and intermediate ranges. It showed that for many women with node-negative breast cancer and a Recurrence Score of 0-25, chemotherapy did not provide a benefit over hormone therapy alone.
For patients with a high Recurrence Score, the data indicates a greater chance of recurrence. The benefit from chemotherapy is significant enough that it is recommended as part of the treatment plan. The genetic profile of these tumors suggests they are more aggressive and more likely to respond to chemotherapy.
The RxPONDER trial clarified treatment for patients whose cancer had spread to the lymph nodes. It demonstrated that postmenopausal women with node-positive cancer and a Recurrence Score of 0-25 did not benefit from adding chemotherapy. However, for premenopausal women in the same situation, chemotherapy did show a benefit, highlighting how the score is combined with other factors to refine decisions.
For scores in the intermediate range, recommendations may depend on other factors. Patient age and specific tumor characteristics might be considered when the score falls into this gray area. This reinforces the score’s role as a tool to guide a collaborative decision-making process.
The Testing Process
Obtaining a 21-gene recurrence score does not require an additional invasive procedure for the patient. The test is performed on a small sample of tumor tissue collected during the initial biopsy or surgery, such as a lumpectomy or mastectomy.
A portion of the preserved tumor tissue is sent to a specialized laboratory for genomic analysis. The lab uses a technique called reverse transcription-polymerase chain reaction (RT-PCR) to measure the expression levels of the 21 genes. These include 16 cancer-related genes and 5 reference genes.
After the analysis, the results are compiled into a report with the Recurrence Score and sent to the oncologist. The process usually takes about two weeks. Once the results are available, the oncologist will consult with the patient to discuss the score’s meaning and its implications for treatment.