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Genomic Tumour Profiling: How Tests Like Oncotype DX Guide Treatment
By Dr. Gajendra Kumar Himanshu
Genomic tumour profiling involves the analysis of the activity of specified genes in cancer tissue to provide information on tumour behaviour and therapy response. Tests like Oncotype DX can assist in assessing the risk of breast cancer recurrence and whether chemotherapy will be beneficial for selected patients. This helps doctors to personalise treatment rather than depend only on tumour size, stage, and other routine results.
In this blog, we discuss genomic tumour profiling, how these tests work, what Oncotype DX assesses, who may benefit, how the results can impact chemotherapy decisions, and why the test is just one part of treatment planning. We will also cover its limitations and what patients should ask their oncologist.
Why Is Genomic Tumour Profiling Necessary?
Two people with breast cancer of identical tumour size and stage can have vastly different risks of recurrence. One tumour may behave rather slowly; another may have biological features that make it more likely to come back.
Doctors already look at several critical characteristics, including size and grade of the tumour, lymph node involvement, oestrogen and progesterone receptor status, HER2 status, age, and menopausal status. Genomic testing provides another piece of information by looking at how genes inside the tumour are working.
This can be particularly helpful when the benefit from treatment is not clear. In some individuals, the result may support treatment with hormone therapy alone, sparing chemotherapy and its possible side effects. For others, it could provide evidence that chemotherapy would be worth having.
What Is Genomic Tumour Profiling?
Genomic tumour profiling is a form of molecular testing done on cancer tissue. Rather than looking at the appearance of the cancer cells under a microscope, the test looks at the activity or expression of specific genes.
This is not the same as hereditary genetic testing. A hereditary test searches for gene alterations that may have been inherited from a parent and can sometimes increase cancer risk in family members. Genomic tumour profiling is targeted at the cancer itself and is often used to understand how it behaves or to assist in guiding treatment.
Depending on the test, tumour profiling can be performed on a limited group of genes or a considerably greater number of genes. Not every patient needs this type of testing, and the right test depends on the type of cancer and the clinical situation.
What Is Oncotype DX?
Oncotype DX is a 21-gene expression test for selected people with early-stage breast cancer. It evaluates the activity of 21 genes in the tumour tissue and provides a Recurrence Score ranging from 0 to 100.
The test is especially relevant to some hormone receptor-positive, HER2-negative breast tumours. In patients with no lymph node involvement or limited lymph node involvement, it can be considered according to the patient's condition.
The result is not a simple 'yes' or 'no' about whether cancer is present. It provides more information regarding the risk of recurrence and the potential benefit of treatment.
How Does Oncotype DX Help With Treatment Decisions?
The Recurrence Score may help clinicians assess whether adding chemotherapy to hormone therapy is likely to help.
A lower score usually means a reduced risk of distant recurrence and a lesser chance that chemotherapy will contribute considerable benefit for many eligible patients. The higher the score, the higher the chance of recurrence, and the more it favours chemotherapy.
The TAILORx trial gave critical data to support this approach. The study indicated that the Recurrence Score could be used to identify many women with hormone receptor-positive, HER2-negative, node-negative breast cancer who could safely forgo chemotherapy, while others with higher scores could benefit from treatment. Age and other clinical characteristics are important too, particularly in women under 50 with intermediate scores.
Menopausal status was also shown to be important in interpreting Oncotype DX results in patients with one to three positive lymph nodes, according to findings from the RxPONDER trial. Therefore, a score should never be interpreted on its own.
How Is the Test Done?
For most individuals, no further biopsy or surgery is required. The laboratory can often evaluate preserved tumour tissue from a previous biopsy or surgery.
The tumour sample is submitted to a specialised laboratory where gene activity is analysed. The resulting report is then examined by the oncology team in conjunction with the patient's pathology and clinical information.
What Are the Benefits of Genomic Testing?
The major advantage is more personalised treatment planning. Rather than presuming that all patients with a specific stage of cancer need the same treatment, genomic information can assist in identifying those who are more or less likely to benefit from chemotherapy.
This may spare some patients from unnecessary chemotherapy and side effects such as fatigue, nausea, hair loss, risk of infection, and other consequences of treatment. At the same time, the ability to identify patients with a higher potential for benefit can help to avoid withholding chemotherapy when it may be advantageous.
What Are the Limits?
Genomic tumour profiling is not suitable for all cancers or all patients. Even when a test is appropriate, the result cannot predict the future with certainty.
Doctors need to weigh the genomic result along with the tumour stage and grade, receptor status, lymph node involvement, age, menopausal status, overall health, and patient preferences.
It is also vital to note that different genomic tests answer different clinical questions. A test meant to assess the probability of recurrence should not be assumed to provide insight into all possible treatments.
If you want to read more about Oncotype DX, then you can visit the official website of the National Cancer Institute.
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Genomic tumour profiling has now become an important feature of personalised cancer care. Tests such as Oncotype DX can provide additional information on the likelihood of recurrence, and are useful for some breast cancer patients and their doctors in determining whether chemotherapy is likely to give considerable benefit. But the result is just one piece of the treatment puzzle. A personalised oncology assessment is still essential for every therapy decision.
If you have been diagnosed with breast cancer and are wondering if genomic tumour profiling or an Oncotype DX test could help guide your therapy, speak to your oncology team at Oncare Cancer Hospital. Your oncologist can assess your pathology, stage, receptor status, and other clinical criteria to determine if genomic testing is appropriate for you.
Disclaimer
This material is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Genomic testing is indicated only in certain clinical circumstances and should be interpreted by a skilled oncology team. Always review your particular test results and treatment choices with your oncologist before making a healthcare decision.
Frequently Asked Questions
Genomic tumour profiling refers to tests that look at the activity or genetic characteristics of cancer cells to provide information that may help assess cancer behaviour, recurrence risk, or treatment response.
Oncotype DX examines the activity of 21 genes in specific breast tumours and provides a Recurrence Score. The result can help assess recurrence risk and help decide if chemotherapy is likely to give extra benefit.
No. The Oncotype DX test is used primarily for certain individuals with particular types of early-stage, hormone receptor-positive, HER2-negative breast tumours. Your oncologist will assess if the test is suitable based on your particular cancer features.
The score can assist in guiding the decision, but it is not the decision. Your oncologist will look at the score alongside other factors such as your age, menopausal status, the stage of your tumour, whether your lymph nodes are involved, the features of your tumour, and your overall health.
Written and Verified by:
Dr. Gajendra Kumar Himanshu Exp: 10 Yr
Medical Officer
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