Medical Oncologist
While on Tagrisso (osimertinib)
Tests and Monitoring — While You Are on Osimertinib
Regular monitoring is part of your osimertinib treatment plan from the first day. The tests are not a sign that something is wrong — they are how your team finds any changes early, when they are easiest to manage.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed August 2026
- Starts before your first dose — Baseline tests give your team a reference point for everything that follows.
- Heart rhythm is monitored throughout — Osimertinib can affect the QTc interval in some patients, so ECGs are a routine part of the schedule.
- Tests space out over time — Monitoring is more frequent early in treatment and less frequent once you are settled and stable.
- Scans check whether the cancer is responding — CT scans are done at intervals to show whether treatment is working.
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Your monitoring schedule on osimertinib includes ECGs, blood tests for liver function and blood count, and CT scans at set intervals. Tests are most frequent in the first weeks and space out once you are stable. Each one gives your team information they cannot get from symptoms alone.
What does the monitoring process look like?
Before your first dose — baseline tests
Your team orders an ECG, an echocardiogram and blood tests for liver function and blood count before you start. These results are your baseline. Every future reading is compared against them, not just against a standard normal range.
First weeks on treatment — closer review
Blood tests are repeated early in treatment. Liver function and blood count are the main focus. Most reactions, if they happen, tend to appear in this period, which is why monitoring is most frequent here.
Ongoing ECGs — heart rhythm checks
ECGs continue at intervals throughout treatment. They measure the QTc interval, which reflects how your heart resets between beats. Osimertinib can lengthen this in some patients, and it usually causes no symptom you would feel on your own.
Periodic blood tests — routine monitoring
Once early checks are clear, blood tests continue at longer intervals. Your team looks at liver enzymes, blood counts and electrolyte levels. Low potassium or magnesium can affect heart rhythm independently of the drug, so these are watched alongside the ECG.
Response assessment scan
A CT scan is done after you have been on treatment for some weeks. It shows whether the cancer is responding — stable, shrinking, or otherwise. PET-CT, when needed, is coordinated with partner imaging centres.
Tell your team at every visit
- Any new or worsening shortness of breath or cough — always worth reporting on osimertinib
- Skin changes: rash, dry or peeling skin, or sores around the nails
- Yellowing of skin or eyes, dark urine, or pain in the upper right side of your abdomen
- Any change in your vision
- Ankle swelling, a racing heartbeat, or a heartbeat that feels irregular
- Every medicine, supplement, vitamin or herbal preparation you are currently taking — some affect the QTc interval
- Whether your appetite or weight has changed
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Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
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Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
Surgical Oncologist
Surgical Oncologist
Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
Surgical Oncologist
Radiation Oncologist
Radiation Oncologist
Radiation Oncologist
Hematologist
Interventional Radiologist
Dr. Mohammed Imran
Surgical Oncologist
Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
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Test-by-test: what your team is watching for
| Test | When | What it measures | What an abnormal result may mean for your treatment |
|---|---|---|---|
| ECG | Baseline, then at set intervals throughout treatment | QTc interval — how long the heart takes to reset between beats | QTc prolongation may need electrolyte correction, closer monitoring or a dose adjustment |
| Echocardiogram | Baseline; repeated if you develop breathlessness or ankle swelling | Left ventricular ejection fraction — how well the heart pumps | Reduced function may need treatment paused and a cardiology review before restarting |
| Liver function tests | Baseline, early weeks, then periodically | Liver enzymes (ALT, AST) and bilirubin | A mild rise may be watched closely; a significant rise may need a dose reduction or treatment break; a severe rise may need treatment stopped |
| Full blood count | Baseline, then periodically | Red cells, white cells and platelets | Anaemia may need supportive treatment; very low white cells may need a dose change |
| Electrolytes (potassium, magnesium) | As clinically indicated | Mineral levels that affect heart rhythm | Low levels are corrected before the next ECG, as they can worsen QTc prolongation independently of the drug |
| CT scan (response assessment) | After some weeks on treatment, then at regular intervals | Cancer size, spread and any new findings | Stable or shrinking disease confirms response; growth or new lesions triggers a treatment review |
Did you know?
Heart rhythm changes on osimertinib can occur without any symptom you would notice yourself.
This is why the ECG schedule runs independently of how you feel — it catches what self-monitoring cannot. Keeping potassium and magnesium levels normal reduces this risk further, which is why your team monitors electrolytes alongside the drug.
Source: NCCN Guidelines for Non-Small Cell Lung Cancer
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Common questions
Frequently asked questions
How often will I need blood tests on osimertinib?
Blood tests are most frequent in the first weeks of treatment and space out once your results are stable. The exact schedule depends on your baseline results, your other health conditions, and how your liver and blood count respond in the early weeks. Your team will give you a schedule at the start and adjust it if anything needs closer attention. Bring a current list of all your medicines to every visit — some can interact with the drug or affect your results.
What is the QTc interval and why does it matter on osimertinib?
The QTc interval is a measurement on your ECG trace that reflects how long your heart takes to reset electrically between beats. Osimertinib can lengthen this interval in some patients. A significantly prolonged QTc can, in rare cases, lead to an abnormal heart rhythm. You would not normally feel this, which is why the ECG is done as a routine check rather than only when you have symptoms. Low potassium or magnesium levels can worsen the prolongation independently of the drug, so these are monitored at the same time.
What happens if one of my test results comes back abnormal?
It depends on which test and how abnormal. A mildly raised liver enzyme may simply be watched more closely at the next visit. A more significant rise may need a short treatment break while the liver recovers. A QTc change may need electrolyte correction before the next dose. Your team will explain any result that needs action and what the next step is. An abnormal result does not automatically mean treatment has to stop — many are managed with adjustments rather than discontinuation.
Can I have my monitoring tests done at a centre close to home?
Ask your oncology team. Blood tests and ECGs can often be done at a local laboratory or clinic if your team accepts results from an external provider. What matters is that results reach your oncologist and are compared against your baseline. CT scans for response assessment may need to be done at or coordinated through your treating centre, because the images need to be read by someone who knows your case and has your previous scans for comparison.
Do I need to fast before any of these tests?
For standard liver function and blood count tests, fasting is not usually required, but practices vary between centres. Some panels ask for fasting beforehand. Ask your team before each test visit whether fasting applies to what is being tested that day. When in doubt, ask before eating on the morning of the test — it is always better to check than to have a test repeated.