Medical Oncologist
Understanding your results
Gefitinib Success Rate: — An Honest Look at the Numbers
You have just been prescribed gefitinib and you want to know whether it works. The honest answer is: it works well for many patients with the right EGFR mutation, but the published numbers describe groups — and no group average tells you what will happen to you specifically.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed August 2026
- Mutation first, drug second — Gefitinib is prescribed because of a gene change in your tumour, not just because of your cancer type. The EGFR mutation result is what the numbers are built on.
- A median is a midpoint, not a limit — Half the patients in a trial did better than the reported median figure. It is not a ceiling or a forecast for any one person.
- Response is not the same as cure — Gefitinib aims to control the cancer for as long as possible. Most patients eventually develop resistance, which is why the next step after gefitinib matters too.
- Your oncologist has your specific numbers — Population-level data from ESMO and NCCN guidelines gives a range. Your oncologist can explain what applies to your mutation type and stage.
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Gefitinib works for many patients with a specific EGFR mutation — exon 19 deletion or exon 21 L858R. In those patients, response rates are substantially higher than chemotherapy, according to ESMO and NCCN guidance. These numbers describe groups, not individuals; your mutation type and overall fitness shape your personal outlook more than any published average.
What do response rates and median survival actually mean?
A response rate tells you what proportion of patients in a clinical trial saw their tumour shrink or stop growing. It is a group figure, not a prediction for any one person in that group.
The median is the middle value when all results are lined up in order. If median progression-free survival is reported as a certain number of months, half the patients in the trial did better than that figure and half did worse. It is a midpoint, not a ceiling.
Both numbers come from trial populations who were carefully selected and monitored at specialist centres. How well they describe your situation depends on how similar you are to that population — and your oncologist is the person best placed to tell you that.
How do doctors measure whether gefitinib is working?
Baseline scans before you start
CT or PET-CT scans measure your tumours precisely before treatment begins. Everything later is compared against these reference images.
First follow-up scans at six to twelve weeks
Most oncology teams image again six to twelve weeks after you start. This is when the first clear picture of response emerges.
Categorising the response
Radiology uses internationally standardised categories — complete response, partial response, stable disease or progression — based on RECIST criteria. Your oncologist will explain which category your scans fall into.
Ongoing monitoring every few months
Scans continue regularly throughout treatment. The aim is to catch any change early, not just to confirm the drug is working.
Resistance testing if the drug loses its effect
If gefitinib eventually stops controlling the cancer, a repeat biopsy or liquid biopsy can identify why. The result determines what comes next.
What affects how well gefitinib works for me?
- Which EGFR mutation you have — exon 19 deletion and exon 21 L858R have different response patterns
- Whether the cancer had already spread to the brain or bone when treatment started
- Your overall fitness and underlying lung function
- Your smoking history — trial data shows consistently different patterns by smoking status
- Whether your tumour carries co-mutations alongside the main EGFR change
- How quickly your symptoms and tumour markers change in the first weeks on treatment
Meet the Specialists
17+ senior cancer specialists. One panel for your case.
Trained at AIIMS, Tata Memorial, and leading international centres. Combined 150+ years of experience. Every complex case is reviewed by 3+ of them — together.
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
Surgical Oncologist
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
Surgical Oncologist
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What happens when gefitinib stops working?
Most patients who respond to gefitinib eventually develop resistance. This is a predictable biological process, not a failure of the treatment decision or the drug.
The most common resistance mechanism is a secondary mutation called T790M. If that is found, a third-generation EGFR inhibitor may be an option. Your team can test for it through a repeat biopsy or a blood-based liquid biopsy.
Resistance does not mean running out of options. It means the next question — what to move to — is answered the same way the first one was: by looking at your tumour biology.
Can survival statistics tell me what will happen to me?
No published statistic can do that, and any source that implies otherwise is not being straight with you. Survival figures describe what happened to a specific group of people under specific trial conditions.
Your mutation type, your age, the extent of spread, your other health conditions and many other factors combine in ways no average captures. Two people with the same cancer type and the same drug can have very different journeys.
The most useful question to ask your oncologist is not 'what is the success rate?' but 'given everything you know about my tumour, what are you aiming for at each stage?' That question has a specific answer for you.
Did you know?
Before EGFR-targeted drugs existed, patients with EGFR-mutated lung cancer received the same chemotherapy as everyone else — and tended to respond less well than unselected patients.
Gefitinib was among the first drugs to demonstrate that matching treatment to a specific gene change, rather than to a cancer type alone, could make a meaningful difference for the patients it fits.
Source: ESMO Clinical Practice Guidelines for Non-Small-Cell Lung Cancer
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- How Does Alectinib Work? The Second-Generation ALK Inhibitor Explained
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- Muscle Pain and High CPK on Alectinib: When to Worry
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- Taking Alectinib: Food, Timing and What to Do If You Miss a Dose
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- Weight Gain, Constipation and a Slow Pulse on Alectinib
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Drug Deep Dive: Osimertinib (Tagrisso)
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- Breathlessness or New Cough on Osimertinib: Recognising Lung Injury (ILD)
- Diet and Nutrition While on Osimertinib
- Drug, Food and Supplement Interactions With Osimertinib
- Fertility, Pregnancy and Contraception on Osimertinib
- Heart Rhythm and Ejection Fraction Changes on Osimertinib
- How Does Osimertinib Work? The Third-Generation EGFR Inhibitor Explained
- How Long Does Osimertinib Take to Work?
- How Long Will You Stay on Osimertinib?
- Osimertinib (Tagrisso): The Complete Patient Guide
- Osimertinib Myths: Clear Scans, Stopping Early and Generic Quality
- Osimertinib Price in India: Brand, Generic and Monthly Cost
- Osimertinib Side Effects: The Complete List and Timeline
- Osimertinib Success Rate and Survival: An Honest Look at the Numbers
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- Tests and Monitoring While You Are on Osimertinib
- When Osimertinib Stops Working: Resistance and What Comes Next
- Who Is Eligible for Osimertinib? EGFR-Mutant Lung Cancer
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Common questions
Frequently asked questions
What is the response rate for gefitinib in EGFR-mutated lung cancer?
ESMO and NCCN guidelines document that a majority of patients with an EGFR exon 19 deletion or exon 21 L858R mutation see their tumour shrink or stabilise on gefitinib — at rates substantially higher than standard chemotherapy in the same group. The exact figures your oncologist will quote come from trials relevant to your specific mutation and stage. Asking for those numbers at your next appointment is entirely reasonable, and your oncologist should be able to show you where your situation sits within the published range.
How long does gefitinib usually work before it stops?
ESMO and NCCN guidelines report median progression-free survival figures for EGFR-mutated patients on gefitinib, and your oncologist can share the relevant figure for your mutation type. Remember that the median is a midpoint: half the patients in the trials continued longer than that figure, and some considerably longer. What your own trajectory will be depends on your specific mutation, your baseline disease and how your body responds — none of which the median predicts for you individually.
Can gefitinib cure lung cancer?
Gefitinib is not described as a curative treatment in ESMO or NCCN guidance for the cancers it is used in. Its aim is to control the cancer for as long as possible while maintaining quality of life. Some patients have long responses measured in years, but most eventually develop resistance. Being clear about that now is not pessimism — it is accurate information that allows you and your team to plan for what comes next while the drug is still working well.
Is gefitinib better than chemotherapy?
For patients with an EGFR exon 19 deletion or exon 21 L858R mutation, ESMO, NCCN and ASCO guidance recommends EGFR-targeted therapy over chemotherapy as first-line treatment, because response rates and progression-free survival are better for those patients. For patients without an EGFR mutation, gefitinib is not recommended, and other treatments are more appropriate. The drug's advantage is specific to the mutation, not to lung cancer broadly.
What happens if my scan shows the cancer is growing while I am on gefitinib?
This is called progression on treatment, and it triggers a reassessment rather than simply stopping treatment with nothing to follow. Your oncologist will likely recommend a repeat biopsy or liquid biopsy to identify the resistance mechanism — the most common is a mutation called T790M, for which a third-generation EGFR inhibitor may be an option. There are other strategies too, depending on your specific situation. Progression on one targeted drug does not exhaust your options; it answers the next question about which direction to go.
How will I know whether gefitinib is working for me?
The clearest answer comes from your scans, typically done six to twelve weeks after you start. Your oncologist will explain which response category your results fall into. You may also notice symptom changes — less breathlessness, less coughing, more energy — before the first scans, though the absence of early symptom change does not mean the drug is not working. The most important thing is to report any new or worsening symptom to your team rather than waiting for your next scheduled appointment.