Cell free DNA for EGFR T790M Mutation Detection Test
About Cell free DNA for EGFR T790M Mutation Detection Test
| Field | Value |
|---|---|
| Also Known As | cfDNA EGFR T790M Test, Liquid Biopsy EGFR T790M, EGFR T790M Resistance Mutation Test, ctDNA EGFR T790M Analysis |
| Sample Type | Peripheral blood (plasma) collected in specialised cfDNA stabilisation tubes |
| Fasting Required | No |
| Report Time | 10 days |
| Recommended For | Adults with non-small cell lung cancer who have progressed on first- or second-generation EGFR-TKI therapy |
| Price | Starting at ₹15,000 |
What is a Cell free DNA for EGFR T790M Mutation Detection Test?
The Cell free DNA for EGFR T790M Mutation Detection test is a specialised blood-based analysis used to identify a specific genetic change that can cause lung cancer to stop responding to certain targeted treatments. It detects the T790M mutation in the EGFR gene (epidermal growth factor receptor, a protein involved in cell growth signalling) using tiny DNA fragments shed by tumour cells into the bloodstream.
This test is also known as a liquid biopsy, as it analyses circulating tumour DNA from a blood sample rather than requiring a tissue sample from the tumour. It is typically prescribed for patients with non-small cell lung cancer (NSCLC) who are on first- or second-generation EGFR-targeted therapy and show signs of disease progression.
What does a Cell free DNA for EGFR T790M Mutation Detection Test Measure?
This test analyses cell-free DNA (cfDNA) extracted from plasma — the liquid portion of blood — for the presence of a specific mutation. The two key elements assessed are described below.
| Component | What It Is | Why It Matters |
|---|---|---|
| EGFR T790M Mutation | A point mutation in exon 20 of the EGFR gene, where threonine is replaced by methionine at position 790 | The most common mechanism by which NSCLC tumours develop resistance to first- and second-generation EGFR-targeted treatments |
| Cell-free DNA (cfDNA) | Highly fragmented DNA fragments released into the bloodstream from dying tumour cells; also called circulating tumour DNA (ctDNA) | Carries tumour-specific genetic information that can be detected without invasive tissue sampling |
The analysis uses droplet digital PCR (polymerase chain reaction), a highly sensitive method capable of detecting mutant DNA sequences at very low levels in the blood.
Why is a Cell free DNA for EGFR T790M Mutation Detection Test Done?
This test is ordered to determine whether a resistance mutation has developed in response to EGFR-targeted therapy, and to guide the next steps in cancer management.
Common Symptoms That May Require This Test
Your oncologist may recommend this test in the following situations:
- Disease progression while receiving first- or second-generation EGFR-targeted treatment such as gefitinib, erlotinib, or afatinib
- New or worsening lung nodules or masses seen on imaging scans
- Increasing breathlessness, persistent cough, or chest discomfort
- Need to determine eligibility for third-generation targeted therapy
- Difficulty obtaining a tissue sample for re-biopsy
Conditions This Test Can Help Detect
This test helps identify a key genetic change linked to treatment resistance in lung cancer. Specific findings include:
- Acquired T790M resistance mutation, found in tumour cells in over 50% of NSCLC patients after disease progression on EGFR-targeted therapy
- EGFR TKI resistance, which develops in approximately 60% of patients who initially responded to erlotinib, gefitinib, or afatinib
- Eligibility for osimertinib (a third-generation EGFR inhibitor), which remains active against the T790M mutation
Cell free DNA for EGFR T790M Mutation Detection Test for Chronic Disease Monitoring
This test plays an important role in the ongoing management of NSCLC. It is typically performed at the point of disease progression to guide treatment decisions after first- or second-generation EGFR therapy.
If the initial result is negative and clinical suspicion remains high, repeat testing may be considered. Research has shown that a second liquid biopsy performed 1 to 8 months after a negative result can increase the number of positive detections by around 50%.
How to Prepare and What to Expect
No special preparation is needed before this test, though there are a few practical steps that help ensure the most accurate result.
Do You Need to Fast?
No fasting is required. You can eat and drink normally before your appointment.
Practical Tips Before Your Test
The following steps will help ensure a smooth collection and accurate processing:
- Bring a detailed clinical history, including your symptoms, previous test results, and treatment history, as this is required for the test
- Inform your oncologist about all current medications and ongoing cancer treatments before the sample is collected
- Bring previous EGFR mutation test reports, including the activating mutation detected at diagnosis, as this information reduces the chance of an uninformative result
- Ensure the sample is collected and dispatched promptly, as proper handling within the required timeframe is essential for cfDNA stability
Step-by-Step Procedure
Here is what happens during and after sample collection:
- A trained phlebotomist draws 10 ml of blood from a vein in your arm using a standard venepuncture technique.
- The blood is collected into a specialised Streck cfDNA stabilisation tube, which preserves the integrity of circulating tumour DNA.
- The sample is stored at 2 to 8°C and dispatched to the laboratory for processing.
- In the laboratory, plasma is separated by double centrifugation and cell-free DNA is extracted using specialised preparation kits.
- The extracted cfDNA is analysed using droplet digital PCR to detect the T790M mutation, even at very low levels (allele frequencies as low as 0.1 to 0.5%).
- Results are reported as "Detected" or "Not Detected," accompanied by an interpretive report.
Factors That Can Affect Accuracy
Several factors can influence how reliably this test detects the T790M mutation:
- Low tumour burden in the bloodstream, which reduces the amount of detectable cfDNA
- Improper sample handling or delays in processing, which can degrade cfDNA quality
- Extreme storage temperatures that may compromise DNA yield and plasma quality
- Lower metastatic burden or absence of bone metastases, which are associated with lower detection rates
Understanding Your Cell free DNA for EGFR T790M Mutation Detection Test Results
Results from this test should always be reviewed and interpreted by a qualified oncologist alongside imaging findings, treatment history, and overall clinical condition.
| Result | Interpretation |
|---|---|
| Not Detected | No T790M mutation identified in the plasma cfDNA sample |
| Detected | T790M mutation is present; the patient may benefit from third-generation EGFR-targeted therapy |
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
A negative result does not entirely rule out the presence of the T790M mutation. If the blood test is negative but clinical suspicion remains, your oncologist may recommend tissue biopsy testing to confirm the finding.
Results During Special Conditions
Patients with higher metastatic burden or bone metastases tend to have higher rates of T790M detection in plasma, as more tumour DNA is shed into the bloodstream. In cases of lower tumour burden, the amount of circulating tumour DNA may be insufficient for reliable detection.
Tumour heterogeneity (variation in genetic changes across different parts of the tumour) may also affect results, as a single sample may not capture all mutations present.
How to Maintain Healthy Levels
While this test does not have "normal" levels in the traditional sense, the following steps support the best possible care:
- Continue all cancer treatments and follow the management plan directed by your oncologist
- Attend all scheduled follow-up appointments and imaging scans without delay
- Report any new symptoms or noticeable changes in your condition to your healthcare team promptly
Lupin Diagnostics Cell free DNA for EGFR T790M Mutation Detection Test Price
The Cell free DNA for EGFR T790M Mutation Detection test costs start at ₹15,000 at Lupin Diagnostics. This test requires a visit to a Lupin Diagnostics centre; home collection is not available for this test.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 15000 |
| CHENNAI | 15000 |
| HYDERABAD | 15000 |
| KOLKATA | 15000 |
| NAVI MUMBAI | 15000 |
| PUNE | 15000 |
Disclaimer: Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
Follow these steps to schedule your Cell free DNA for EGFR T790M Mutation Detection test at Lupin Diagnostics:
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred centre location.
- Visit the centre at your scheduled time for sample collection.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Frequently Asked Questions
The EGFR T790M mutation is a specific genetic change in the EGFR gene that is the most common cause of resistance to first- and second-generation EGFR-targeted treatments in non-small cell lung cancer. Detecting this mutation helps doctors determine whether a patient may benefit from third-generation targeted therapy.
This test uses a simple blood draw to analyse tumour DNA fragments circulating in the bloodstream, making it far less invasive than a tissue biopsy. A tissue biopsy requires a surgical or guided procedure to collect a sample directly from the tumour, which is not always possible or practical at the time of disease progression.
A negative result means no T790M mutation was detected in the plasma sample at the time of testing. However, a negative result does not completely rule out the mutation. If clinical suspicion remains, your oncologist may recommend a tissue biopsy or a repeat liquid biopsy at a later stage.
The test uses droplet digital PCR, which can detect the T790M mutation at allele frequencies as low as 0.5%. Studies report a concordance of around 77% between plasma and tissue-based results. Accuracy is influenced by tumour burden and metastatic spread, with higher detection rates in patients with greater metastatic disease.
Providing your clinical history, including the original EGFR activating mutation detected at diagnosis, helps the laboratory interpret results accurately and reduces the likelihood of an uninformative result. Your oncologist will usually prepare this documentation before the sample is collected.
Yes. If the initial result is negative and your oncologist suspects the mutation may still be present, a repeat Cell free DNA for EGFR T790M Mutation Detection test may be recommended 1 to 8 months later. Repeat testing has been shown to identify additional positive cases that were missed in the first round.
Results are typically available within 10 days from the date of sample collection at Lupin Diagnostics. The turnaround time reflects the specialised nature of the droplet digital PCR analysis used for this test.
Cell free DNA for EGFR T790M Mutation Detection Test
