Cancer recurrence is something we discuss often with our patients, because even after completing treatment, the possibility of cancer returning is very real and understandably worrying. At our centre, we meet many individuals who come in with questions about follow-up care, rising markers, or new symptoms, and one of the tools we rely on to guide them is the PET CT scan.
We’ve seen how combining metabolic information from PET with anatomical detail from CT helps us identify disease earlier and more accurately. The tracer, usually a glucose analogue like FDG, accumulates in active cancer cells, allowing us to detect changes before they become structurally visible on a CT alone.
In simple terms, the CT shows where something is, while the PET shows how active it is. When both images are fused, we get a clear picture that helps us understand whether a suspicious area may represent recurrence.
In our experience with our PET scan in Bangalore, this combined approach often allows us to detect potential recurrence sooner rather than waiting for symptoms and relying only on conventional scans.
Why does cancer recurrence happen?
It’s vital to understand that despite apparently successful initial treatment, cancer recurrence remains a possibility. Some of the common reasons:
- Microscopic residual disease: Even when surgery or chemotherapy has removed a visible tumor, tiny clusters of cells may remain and later grow.
- Treatment resistance: Some cancer cells may survive initial therapy because they are less sensitive and later proliferate.
- Metastatic seeding: Cancer may have already spread microscopically at the time of initial treatment, and these foci may remain dormant and then become active.
- Host/tumor factors: Tumor biology (grade, stage, type), patient immune response, and other factors influence recurrence risk.
This is a major reason why I recommend regular surveillance and consideration of sensitive imaging such as PET CT scan, as part of the monitoring strategy.
Role of PET CT scan in detecting cancer recurrence
Using a high-sensitivity modality, such as a PET CT scan, offers several advantages when monitoring for cancer recurrence:
- Early detection: PET CT may detect recurrent disease before symptoms appear or before changes on conventional imaging.
- Precise localization: It helps identify the exact site of recurrence (local/regional vs distant), which is critical for planning additional therapy.
- Impact on management: Detecting recurrence early can allow timely intervention, potentially improving outcomes, reducing morbidity.
- Monitoring therapy: After detection of recurrence and start of treatment, PET CT can help assess response and viability of the tumor.
In our Bangalore centre at Kiran PET/CT, we use PET CT scan not as a routine screening for all patients but in those with clinical suspicion (rising markers, new symptoms, imaging ambiguity) or high-risk cases.
Limitations and cautions:
- False positives and false negatives do occur: some non-cancerous processes (inflammation, infection) may show uptake; some tumor types have low tracer avidity.
- Cost and radiation exposure need discussion with the patient.
- Not a substitute for clinical review, blood tests, and other imaging.
Key cancer types and recurrence scenarios
Cancer recurrence breast
In breast cancer follow-up, recurrence may be local (in the breast or chest wall), regional (lymph nodes), or distant (bone, lung, liver). Imaging strategy depends on stage, subtype, and patient risk.
The PET CT scan is useful, particularly when conventional imaging is inconclusive or if tumor markers/clinical symptoms suggest recurrence.
As the treating doctor, I counsel my breast cancer patients about the possibility of recurrence, what the PET CT scan can show, and when it is appropriate.
Ovarian cancer recurrence rate and treatment
Ovarian cancer has one of the highest recurrence rates. Research shows that depending on the stage at diagnosis, recurrence may occur in up to ~80% of patients.
For example, at an advanced stage, the recurrence rate is very high.
On treatment: When recurrence of ovarian cancer occurs, treatment may include further surgery, chemotherapy, targeted therapy, and/or maintenance therapy depending on features.
Here, the PET CT scan plays an important role in localizing relapse (especially extra-pelvic) and guiding therapy choice.
In my Bangalore practice, for a patient treated for ovarian cancer, if we detect a rising tumor marker (e.g., CA-125) or new symptoms, we consider a PET CT scan to check for early relapse.
Bladder cancer recurrence after 5 years
Bladder cancer is notorious for recurrence, even after apparently successful treatment. The risk continues, though the pattern depends on muscle invasion, grade, and other factors. Some studies show that for high-grade non-muscle-invasive disease, the 5-year recurrence rate may be ~42%.
While routine PET CT may not be used in every bladder cancer follow-up, if recurrence is suspected (especially extravesical or distant spread), the PET CT scan can assist. In my practice, I emphasize to patients that even after 5 years, they cannot become complacent.
Lung cancer recurrence after 5 years
In lung cancer, the majority of recurrences are seen within the first 3 years post-treatment; a much smaller proportion appears after 5 years.
However, “after 5 years” does not mean zero risk. For a patient treated for lung cancer, if new symptoms develop or imaging is ambiguous, a PET CT scan is a useful option to investigate possible late recurrence. I advise patients accordingly: ongoing vigilance is required.
Prostate cancer recurrence after 5 years
With prostate cancer, recurrence often presents as a biochemical recurrence (PSA rise) rather than clinically obvious disease. Estimates suggest that about 20-30 % of men may relapse after 5 years from initial therapy.
In this scenario, imaging modalities, including PET CT (with specific tracers in certain centres), are increasingly used to localize recurrent disease when PSA rises. In our centre, we discuss with the patient the utility of a PET CT scan when appropriate.
PET scan in Bangalore – what to know
For patients based in Bangalore (and surrounding areas) looking for a PET scan in Bangalore, here is what I cover during counselling:
- Facility: We have access to a high-quality PET CT scanner at our centre in Kiran PET CT, staffed by nuclear medicine specialists and radiologists experienced in oncology imaging
- Preparation: The patient may need to fast for a certain number of hours, blood sugar controlled, tracer injection, and have a waiting period.
- Timing: We recommend a PET CT scan in follow-up if there is a specific indication (rising marker, new symptom, suspicious conventional imaging) rather than as a blanket test.
- Cost & support: We discuss cost, insurance, and any subsidies.
- Interpretation: Results are integrated into the overall clinical context, history, prior therapy, tumor type, and markers.
- Follow-up: If PET CT indicates recurrence, we discuss multidisciplinary management (surgery, chemo, targeted therapy) in consultation with the patient.
In practice, this imaging tool complements other follow-up methods (clinical review, blood tests, conventional imaging) and adds important value in appropriate cases.
Final Thoughts
In summary, as an oncologist working in Bangalore at our centre in Kiran PET/CT, I emphasize the importance of vigilance for cancer recurrence even after successful initial treatment.
The PET CT scan is an excellent tool in our armamentarium for detecting recurrence early, precisely locating it, and guiding further therapy, particularly in complex scenarios such as breast cancer recurrence, ovarian cancer recurrence treatment, bladder cancer recurrence after 5 years, lung cancer recurrence after 5 years, and prostate cancer recurrence after 5 years.
However, it is not a standalone test; its value is highest when used appropriately, in the context of each patient’s risk and clinical picture. I encourage patients to remain engaged with follow-up care, to report new symptoms promptly, and to discuss with their oncologist whether a PET CT scan is indicated in their specific case.
FAQs
Q1. What exactly is meant by “cancer recurrence”?
Cancer recurrence refers to the return of cancer after a period during which it could not be detected (remission). It may occur locally, regionally, or distantly.
Q2. Why might a PET CT scan be preferred over a conventional CT alone in suspected recurrence?
Because PET CT combines metabolic activity (which can appear earlier) with anatomical imaging, it can detect recurrent lesions that might not yet have produced a size change visible on CT. This leads to earlier detection and better localization.
Q3. Is a PET CT scan recommended for all cancer survivors routinely?
Not necessarily. It’s used selectively in patients with a high risk of recurrence, rising markers, new symptoms, or inconclusive imaging. Routine use without indication may not be cost-effective or beneficial.
Q4. How long after initial therapy should I remain vigilant for recurrence (for example, breast, ovarian, bladder, lung, or prostate)?
It depends on the type and stage of cancer. For example:
- Ovarian cancer: high recurrence rate, especially in advanced stages.
- Bladder cancer: even after 5 years, some risk remains.
- Lung cancer: most recurrences occur within 3 years, but late recurrences exist.
- Prostate cancer: recurrence (particularly biochemical) may occur after 5 years in ~20-30% of men.
Therefore, long-term follow-up remains important.
Q5. What should I expect if a PET CT scan suggests recurrence?
The result will be discussed by your oncologist and imaging team. If a recurrence is detected, we will assess whether surgery, additional chemotherapy, radiation, or targeted therapy is appropriate. The earlier we detect recurrence and localize it, the better the chance of a tailored intervention.
