PML-RARA QUANTITATIVE – MC061
📉 Leukemia Monitoring (MRD Analysis)📋 Test Specifications
- Report Time: 4th Working Day.
- Method: Real-Time PCR (RT-qPCR).
- Sample Type: Whole Blood (EDTA) or Bone Marrow Aspirate.
- Test Code: MC061
Overview: Why Measure the Quantity?
Acute Promyelocytic Leukemia (APL) is a distinct subtype of Acute Myeloid Leukemia (AML) characterized by a specific genetic mutation: the PML-RARA fusion gene (caused by a translocation between chromosomes 15 and 17). While the Qualitative test simply tells us if the mutation exists (Yes/No), the Quantitative test tells us exactly how much of it is present.
This test measures the Tumor Burden or Leukemic Load. It counts the number of PML-RARA gene copies in your blood or marrow. This number is vital for monitoring how well the treatment (usually ATRA + Arsenic Trioxide) is killing the cancer cells.
The Concept of Minimal Residual Disease (MRD)
Even when a patient is in remission and feels completely fine, microscopic amounts of leukemia cells may still hide in the body. This is called Minimal Residual Disease (MRD). Standard blood tests and microscopes cannot see these tiny amounts.
The PML-RARA Quantitative test is highly sensitive. It can detect even 1 cancer cell in 100,000 normal cells. This sensitivity allows doctors to predict a relapse months before it actually happens clinically.
When is this Test Ordered?
After the first phase of treatment (Induction), doctors test to see if the PML-RARA levels have dropped significantly (e.g., by 2-3 logs). A rapid drop indicates a good prognosis.
Throughout the treatment course, regular testing ensures that the levels continue to fall until they become undetectable (Molecular Remission).
After treatment is finished, patients are tested every 3 months for up to 2-3 years. If the test suddenly shows a rising number of copies (Molecular Relapse), doctors can restart therapy immediately to prevent a full-blown clinical relapse.
Understanding Your Report
The report will provide a value, often expressed as a Normalized Copy Number (NCN). This compares the leukemia gene (PML-RARA) to a control gene (like ABL) to ensure accuracy.
- Decreasing Trend: If your copy number goes from 10,000 to 100 to 0 over months, the treatment is working perfectly.
- Undetectable (Negative): This is the goal. It means the leukemia burden is so low it cannot be measured. This is called Complete Molecular Remission (CMR).
- Increasing Trend: If the number was 0 and suddenly becomes 50 or 100, it is an early warning sign of relapse.
Why choose RT-PCR over Qualitative testing?
A Qualitative test is like a light switch—it's either On or Off. It is great for initial diagnosis. However, it cannot tell if the cancer is shrinking or growing.
A Quantitative test is like a dimmer switch it tells you exactly how bright the light is. In cancer treatment, knowing how much cancer is left determines if you need more chemotherapy or if you can stop. It prevents over-treatment and under-treatment.
Frequently Asked Questions
For Quantitative monitoring, Bone Marrow is traditionally considered more sensitive because leukemia starts there. However, modern PCR techniques are so sensitive that Peripheral Blood is now widely accepted for routine monitoring, sparing the patient from painful marrow biopsies every few months.
Typically, it is done at diagnosis, then after every chemotherapy cycle (Induction, Consolidation), and then every 3 months for 2 years after finishing treatment. Your Oncologist will set the exact schedule.
If you are in the middle of treatment, this is normal; the numbers should be going down. If you finished treatment long ago and get a low positive, doctors will repeat the test in 2-4 weeks to see if it is rising (relapse) or just a fluctuation.
Yes. This is a genetic test and is not affected by food. No fasting is required.
Disclaimer: This is a highly specialized oncological test. Results must be interpreted by a Hematologist in the context of the patient's treatment history.