Medical Oncologist
Drug Deep Dive: Gefitinib (Iressa)
How Long Will You Stay — on Gefitinib?
Gefitinib has no fixed end date. You take it every day for as long as it holds your cancer stable or reduces it — and for as long as you can tolerate it. Your scan results, not the calendar, decide when that changes.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed August 2026
- No fixed course — Unlike some chemotherapy regimens, gefitinib is not prescribed for a set number of cycles.
- Scans decide it — Your oncologist uses CT results at regular intervals to decide whether to continue or stop.
- Resistance is expected — Most EGFR-mutated cancers eventually develop resistance. This is anticipated, and there are next steps.
- Stopping rules are clear — The main reasons to stop are confirmed disease progression on scans or side effects that cannot be managed.
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Gefitinib is taken every day for as long as it keeps working and you can tolerate it. There is no fixed number of weeks or months. Your oncologist reviews your scans at regular intervals and continues treatment when the cancer is stable or responding. The stopping rule is what the cancer is doing, not the calendar.
What keeps you on gefitinib, and what stops it?
Gefitinib is continued for as long as two things are true: your scans show the cancer is stable or responding, and the side effects are at a level you can manage.
The main reason to stop is confirmed disease progression — scans showing the cancer has grown or spread compared with the previous image. Unacceptable side effects that cannot be controlled with dose adjustment or supportive medication are the other reason.
You do not stop because a fixed number of months have passed. NCCN and ESMO guidance for EGFR-targeted therapy is to continue until one of those stopping conditions is met.
What does your team check at each review?
CT scans are arranged at regular intervals to track how the cancer is responding. Your oncologist looks at the trend across several scans, not a single image in isolation.
Blood tests at each visit check liver function, because gefitinib can affect the liver in some patients. Your team will also ask about symptoms — breathlessness, skin reactions, appetite — that give a fuller picture between scans.
If scans show stable disease or a response, and you are tolerating the tablet, the standard approach is to continue.
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Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
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Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
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Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
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Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
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Dr. Mohammed Imran
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Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
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When does gefitinib stop working, and what comes next?
Most EGFR-mutated cancers treated with first-generation EGFR inhibitors develop resistance over time. This is the cancer adapting, not a sign that treatment failed.
The most common mechanism is a specific acquired change in the EGFR gene called T790M. When progression is confirmed on scans, your oncologist may arrange a liquid biopsy or a repeat tissue biopsy to identify why the cancer started growing again.
If T790M is found, osimertinib is approved and recommended by both NCCN and ESMO as the next step. If it is not found, other options will be discussed based on your specific situation.
Terms your oncologist may use about response and duration
- Disease progression
- The cancer has grown or spread compared with the previous scan. This is the main clinical reason to stop gefitinib and reassess the plan.
- Stable disease
- The cancer has neither grown meaningfully nor shrunk. On a targeted therapy, stability is a positive result — it means the drug is doing its job.
- Partial response
- The tumour has shrunk compared with the scan before treatment. This is seen in a proportion of patients, often earlier in the course of treatment.
- Acquired resistance
- The cancer has found a way to grow despite gefitinib being present. It happens in most patients over time and does not mean all options are exhausted.
- T790M mutation
- A specific genetic change in the cancer cell's EGFR gene that is the most common reason gefitinib eventually stops working. It is detectable by blood test or biopsy, and its presence points to a specific next treatment.
Questions patients ask about staying on gefitinib
Can I take a planned break from gefitinib?
Taking a break without medical advice is not recommended. EGFR inhibitors work by maintaining a continuous block on the protein that drives cancer cell growth, and a gap in treatment can allow the cancer to regrow. If you are struggling — with side effects, with the daily routine, or with anything else — tell your team rather than stopping quietly. There may be dose adjustments or practical support that help. A planned pause, if one is ever appropriate, should be decided by your oncologist, not by stopping the tablet yourself.
I feel completely well. Can I stop gefitinib early?
Feeling well is a sign the drug is working, not a sign you can stop. EGFR-mutated lung cancer is managed by gefitinib rather than cured by it in most patients, and in a proportion of cases the cancer regrows when treatment stops even when scans were clear. The evidence base that NCCN and ESMO guidance is built on comes from patients who continued daily. Until robust evidence for stopping in remission exists for this treatment, oncologists follow the established approach: continue while it is working and you are tolerating it.
How long have other people stayed on gefitinib?
Clinical studies report a range, and population averages do not translate reliably into individual predictions. What you read online or hear from other patients reflects a specific group at a specific time. Your cancer's profile — the particular EGFR mutation type, what other molecular changes are present — influences the answer for you individually. Your oncologist can give you a realistic picture for your mutation type. The most useful number is not how long others stayed on it but what your own scans are currently showing.
What if side effects become hard to manage?
Your oncologist may reduce the dose, pause treatment temporarily, or manage specific side effects with additional medicines — for example, a topical cream for skin reactions or dietary guidance for diarrhoea. These steps aim to let you continue on treatment rather than stopping it entirely. Serious reactions, such as a significant rise in liver enzymes or signs of lung inflammation, may require treatment to be held while the problem is assessed. Your team then weighs the benefit of restarting against the risk based on what happened.
How soon will I know whether gefitinib is working?
Your first assessment scan is usually arranged a few months after starting. Some patients notice symptom improvement before the first scan — breathlessness easing, or energy returning — but a symptom change alone is not what your team uses to measure response. The scan result is. Your oncologist will explain before the scan what they are looking for and what different results would mean for the plan going forward, so you are not waiting without a framework.
Explore 75 more Lung Cancer Targeted Medicines topics
Drug Deep Dive: Gefitinib (Iressa)
- Diarrhoea on Gefitinib: Home Management and Warning Signs
- Diet and Nutrition While on Gefitinib
- Fertility, Pregnancy and Contraception on Gefitinib
- Gefitinib (Iressa, Geftinat, Geftib): The Complete Patient Guide
- Gefitinib Myths: 'It's Only for Poor Patients' and Other Half-Truths
- Gefitinib Plus Chemotherapy: Does Adding Chemo Actually Help?
- Gefitinib Price in India: Brand, Generic and Monthly Cost
- Gefitinib Rash: Why It Appears in Week Two and How to Treat It
- Gefitinib Side Effects: The Complete List and Timeline
- Gefitinib Success Rate and Survival: An Honest Look at the Numbers
- Gefitinib and Antacids: The Interaction That Silently Reduces Absorption
- Gefitinib in Early-Stage vs Advanced Lung Cancer: Different Goals
- Gefitinib in Elderly Patients and Those With Other Illnesses
- Gefitinib vs Osimertinib: Making the Decision When Cost Matters
- How Does Gefitinib Work? The First-Generation EGFR Inhibitor Explained
- How Long Does Gefitinib Take to Work?
- How Long Will You Stay on Gefitinib?
- Raised Liver Enzymes on Gefitinib: What Your LFT Report Means
- T790M Testing After Gefitinib Stops Working: The Next Step Explained
- Taking Gefitinib: Food, Timing and What to Do If You Miss a Dose
- Tests and Monitoring While You Are on Gefitinib
- When Gefitinib Stops Working: Resistance and What Comes Next
- Who Is Eligible for Gefitinib? EGFR-Mutant Lung Cancer
- Will Insurance or a Government Scheme Pay for Gefitinib?
- Work, Travel and Daily Life on Gefitinib
Drug Deep Dive: Alectinib (Alecensa)
- Alectinib (Alecensa, Alectinib): The Complete Patient Guide
- Alectinib After Surgery for Early-Stage ALK-Positive Lung Cancer
- Alectinib Myths: Is ALK-Positive Cancer 'Curable'?
- Alectinib Price in India: Brand, Generic and Monthly Cost
- Alectinib Side Effects: The Complete List and Timeline
- Alectinib Success Rate and Survival: An Honest Look at the Numbers
- Alectinib and Brain Metastases: How It Protects the Brain
- Alectinib in Elderly Patients and Those With Other Illnesses
- Alectinib vs Crizotinib vs Lorlatinib: Choosing an ALK Inhibitor
- Diet and Nutrition While on Alectinib
- Do You Need Chemotherapy Alongside Alectinib?
- Drug, Food and Supplement Interactions With Alectinib
- Fertility, Pregnancy and Contraception on Alectinib
- How Does Alectinib Work? The Second-Generation ALK Inhibitor Explained
- How Long Does Alectinib Take to Work?
- How Long Will You Stay on Alectinib?
- Muscle Pain and High CPK on Alectinib: When to Worry
- Severe Sun Sensitivity on Alectinib: Preventing Serious Burns
- Taking Alectinib: Food, Timing and What to Do If You Miss a Dose
- Tests and Monitoring While You Are on Alectinib
- Weight Gain, Constipation and a Slow Pulse on Alectinib
- When Alectinib Stops Working: Resistance and What Comes Next
- Who Is Eligible for Alectinib? ALK-Positive Lung Cancer
- Will Insurance or a Government Scheme Pay for Alectinib?
- Work, Travel and Daily Life on Alectinib
Drug Deep Dive: Osimertinib (Tagrisso)
- Adjuvant Osimertinib After Lung Cancer Surgery: Three Years of Tablets
- 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
- Osimertinib With Chemotherapy: Who Actually Benefits From the Combination?
- Osimertinib and Brain Metastases: Why It Works Inside the Brain
- Osimertinib in Elderly Patients and Those With Other Illnesses
- Osimertinib vs Gefitinib and Erlotinib: Is the Costlier Drug Worth It?
- Rash, Dry Skin and Nail Problems on Osimertinib
- Taking Osimertinib: Food, Timing and What to Do If You Miss a Dose
- 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
- Will Insurance or a Government Scheme Pay for Osimertinib?
- Work, Travel and Daily Life on Osimertinib
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Common questions
Frequently asked questions
Is there a fixed number of months I will be on gefitinib?
No. Gefitinib is not prescribed for a set number of cycles the way some chemotherapy regimens are. You continue for as long as your scans show the cancer is responding or stable and the side effects remain manageable. Some patients stay on it for many months, others for longer. The answer for your situation comes from your own scan results over time, not from a predetermined duration.
What happens after gefitinib stops working?
Your oncologist will first want to understand why it stopped. A liquid biopsy or a repeat tissue biopsy can identify the mechanism of resistance — most commonly a T790M mutation in the EGFR gene. If T790M is found, osimertinib is approved and recommended by NCCN and ESMO as the next step. If T790M is not found, or other changes are identified, your oncologist will discuss the options that apply to your specific situation. Running out of one treatment does not mean running out of options.
Is gefitinib taken at home or in hospital?
Gefitinib is an oral tablet taken at home, once a day. You do not come to the clinic for each dose the way you would for intravenous chemotherapy. Clinic visits are for monitoring — blood tests, scans, and review appointments — not for the drug itself. This is one of the practical differences between EGFR-targeted therapy and intravenous treatment.
Does the type of EGFR mutation affect how long gefitinib works?
Yes, to some extent. The two most common EGFR mutations — exon 19 deletion and exon 21 L858R — respond somewhat differently, and rarer mutations respond differently again. Your oncologist will have considered your specific mutation when recommending gefitinib. If you are unsure which mutation you have, ask for the molecular pathology report to be explained to you — it is your result and you are entitled to understand it.
Do I need to stop gefitinib before surgery or another procedure?
Usually, yes — for a period around a major procedure, because EGFR inhibitors can affect wound healing. The exact timing depends on the type of surgery and your overall situation, and is decided jointly by your oncologist and the surgeon. Never stop gefitinib on your own before a procedure without speaking to your oncology team first — they need to plan the pause and the restart together.
What happens at CION when gefitinib stops working?
Your CION oncologist will review the situation, arrange the appropriate molecular testing, and discuss next treatment options with you. Immunotherapy, where relevant, is administered as day care at CION. PET-CT for response assessment is coordinated with partner imaging centres. CION does not provide CAR-T or cell therapy; if that becomes relevant to your care, your team will refer you to a centre that does.