Medical Oncologist
Monitoring & response assessment
How Often Will I Need — Scans on Targeted Therapy?
Your scan schedule is set by your treatment protocol, not a single fixed rule. What matters most is what each scan shows — and understanding those results is what this page is for.
Medically reviewed by Dr. Bharati Devi Gorantla, Medical Oncologist, MBBS · MD · DM (Adyar, Chennai) · ECMO · MRCP SCE (UK) · Last reviewed August 2026
- Decided by your protocol — There is no single universal scan timetable. The frequency is built into your treatment plan from the start.
- Results drive decisions — Each scan tells your team whether the treatment is working, holding steady or needs to change.
- Stable can be a good result — A cancer that is not growing is being controlled. For many targeted therapies, that is a meaningful treatment goal.
- New symptoms change the schedule — If you develop new symptoms between scans, tell your team the same day — they may bring your next scan forward.
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Your scan schedule on targeted therapy is decided by your treatment protocol. Your oncologist uses these scans to assess how the cancer is responding, and the results — not the calendar alone — drive decisions about whether to continue, adjust or change your treatment.
What do the different scan results mean?
| Result category | What it means on the scan | What it means for your treatment |
|---|---|---|
| Complete response (CR) | No evidence of active cancer can be found on imaging | The treatment has achieved its main aim. Your oncologist will discuss the next phase — monitoring, a maintenance approach or a planned break. |
| Partial response (PR) | The cancer has become measurably smaller | The treatment appears to be working. You will usually continue on the same treatment and have a repeat scan at the next scheduled interval. |
| Stable disease (SD) | The cancer has neither grown significantly nor shrunk | The treatment is controlling the disease. For targeted therapies, this is often a meaningful and intended result — not a failure. |
| Progressive disease (PD) | The cancer has grown or new areas have appeared | Your oncologist will discuss whether to change your treatment, add to the current regimen, or review your options with you. |
Why does your scan schedule change over time?
Most targeted therapy protocols include a scan some weeks after you start treatment to get a first reading of how the cancer is responding. After that, scans are typically repeated at regular intervals for as long as you are on treatment.
If your results are stable and your side effects are manageable, your team may extend the time between scans. If you develop new or worsening symptoms between scheduled scans, tell your team the same day — they may bring your next scan forward rather than waiting.
The type of scan may also change over time, depending on which imaging shows the cancer most clearly or what your team needs to assess at a given point.
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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)
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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)
Surgical Oncologist
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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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What do the words in your scan report mean?
- Baseline scan
- The scan done before treatment starts, which gives your team a fixed reference point. For you, this means every future scan is compared back to this one to judge whether and how much the cancer has changed.
- Response assessment
- The formal process of comparing your current scan to your baseline or last scan to classify how the cancer has responded. For you, this is what your oncologist is doing when they review your scan results at a clinic appointment.
- RECIST criteria
- A standardised system that radiologists use to measure tumour size and categorise the result — developed so that responses mean the same thing across different hospitals and clinical trials. For you, this is why your report may include specific measurements in millimetres alongside terms like partial response or stable disease.
- CT scan
- A cross-sectional X-ray scan that produces detailed images of internal organs and tumours. For you, this is the most commonly used scan for response assessment during targeted therapy.
- PET-CT
- A scan that combines structural imaging with information about metabolic activity — cancer cells tend to absorb more of the tracer than normal tissue does. For you, this may be used at specific points when your team needs to understand not just the size but the activity of the disease.
- Tumour marker
- A substance measured in a blood test — such as CEA, CA 125 or PSA — that some cancers produce in detectable amounts. For you, your team may track this alongside scans as an additional signal of how the disease is behaving, though markers alone are not used to make treatment decisions.
Did you know?
Stable disease — a cancer that has neither grown nor shrunk — is recognised under RECIST 1.1 criteria and ESMO guidance as a valid treatment response, not an absence of one.
For many patients on targeted therapy, controlling the disease for an extended period is the primary treatment goal, not tumour shrinkage.
Source: ESMO Clinical Practice Guidelines; RECIST 1.1 criteria (Eisenhauer et al., European Journal of Cancer, 2009)
Explore 39 more Monitoring, Resistance & Long-Term Response topics
Monitoring, Scans & Response Assessment
- Are Tumour Markers Reliable on Targeted Therapy?
- Complete Response, Partial Response, Stable Disease: What Each Means
- Do I Need Regular Brain MRIs on Targeted Therapy?
- How Doctors Measure Whether Targeted Therapy Is Working
- How Often Will I Need Scans on Targeted Therapy?
- How to Read a CT or PET Scan Report Without Panicking
- Is 'Stable Disease' Good News or Bad News?
- Scanxiety: How to Get Through the Wait for Scan Results
- Tumour Flare and Pseudoprogression: When Growth Isn't Really Growth
- Understanding PFS, OS and Median Survival Without Losing Hope
- What Happens at a Follow-Up Visit: A Walk-Through
- Which Blood Tests Are Repeated Every Month and Why
- ctDNA Monitoring: Can a Blood Test Predict Progression Early?
Long-Term Response, Stopping & Survivorship
- Am I Still a Cancer Patient? Identity After Long-Term Response
- Bone Health, Heart Health and Late Effects to Monitor
- Can You Ever Stop Targeted Therapy If the Cancer Is Gone?
- Drug Holidays: Are Planned Breaks Safe?
- Follow-Up Schedule After Stopping Targeted Therapy
- How Long Do You Have to Stay on Targeted Therapy?
- Long-Term Effects of Taking a TKI for 5 or 10 Years
- Restarting Treatment After a Break
- Treatment-Free Remission in CML: Who Can Stop Their TKI?
- Your Survivorship Care Plan: What Should Be In It
Resistance, Progression & Next Lines
- Being Told 'There Are No More Options': Is That Really True?
- Brain Metastases on Targeted Therapy: Does Your Drug Reach the Brain?
- Can You Continue the Same Drug After Progression?
- Combination Therapy to Overcome Resistance
- Do You Need Another Biopsy When the Cancer Progresses?
- Histologic Transformation: When Lung Cancer Changes Type
- How to Emotionally Process a Progression Scan
- Leptomeningeal Disease: Symptoms, Diagnosis and Treatment
- Life After ALK Inhibitor Resistance: Sequencing Your Options
- MET Amplification and Other Bypass Resistance Mechanisms
- Oligoprogression: When Only One or Two Spots Grow
- Primary vs Acquired Resistance: Two Very Different Problems
- Should You Change Hospitals After Progression?
- What Happens After Osimertinib Stops Working?
- What Is Sequencing and Why the Order of Drugs Matters
- Why Does Targeted Therapy Stop Working? The Biology of Resistance
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Common questions
Frequently asked questions
How long after starting targeted therapy will I have my first scan?
The timing is set by your treatment protocol and varies by cancer type, drug and centre. What is consistent across NCCN and ASCO guidance is that the first assessment scan is done early enough to detect both a response and any sign that the treatment is not working before too much time passes. Ask your oncologist specifically when your first scan is scheduled and what the appointment will involve.
What does stable disease mean — is it good news or bad?
Stable disease means the cancer has not grown significantly and has not shrunk either. Whether this is the result your oncologist was hoping for depends on your specific cancer type and the treatment you are on. For many targeted therapies, controlling growth for a sustained period is exactly the intended goal — it is not a failure. Ask your oncologist directly whether stable disease on your scan is in line with what the treatment is expected to achieve for your situation.
What is RECIST and why does it appear in my scan report?
RECIST — Response Evaluation Criteria in Solid Tumours — is a standardised system radiologists use to measure tumour size on scans and classify the response as complete, partial, stable or progressive. It was developed so that assessments mean the same thing across different hospitals, countries and clinical trials. When it appears in your report, it means the radiologist has applied these standard measurements to categorise your result consistently.
Can a scan miss cancer?
Scans have resolution limits, and very small clusters of cancer cells can be below the threshold of what current imaging can detect. This is why your team uses several pieces of information together — scans, blood tests, symptoms and clinical examination — rather than relying on any single result alone. If you develop new symptoms that do not match your scan result, tell your team. Clinical judgement, not the scan alone, guides decisions.
Will I need scans after I finish targeted therapy?
Usually yes. Follow-up scans after completing treatment are used to check that the response has been maintained and to detect any recurrence early. The frequency and duration of follow-up imaging varies by cancer type and your individual situation. Your oncologist should give you a follow-up schedule at or before the end of active treatment — if you have not been told what to expect, that is a reasonable question to ask at your next appointment.
What happens if my scan shows progressive disease?
Progressive disease means the current treatment is no longer controlling the cancer effectively enough to continue. Your oncologist will review your situation — this typically involves discussing whether a different targeted agent, a different type of treatment, or entry into a clinical trial is appropriate. Progressive disease on one treatment does not mean you are out of options. Ask your team what the next steps are and what alternatives are being considered for you.