From more treatment to smarter treatment: how tumour‑informed ctDNA monitoring can reduce harm and free capacity in cancer care

Cancer services across the Nordics are under familiar pressure: rising incidence, tighter staffing, constrained imaging capacity, and a growing expectation that care should be both more precise and more humane. Yet follow‑up pathways are still dominated by a pattern that is, by design, late and often blunt: treat, scan on a fixed schedule, then react.

Tumour‑informed circulating tumour DNA (ctDNA) monitoring offers a practical way to modernise that pathway. Not by replacing imaging or systemic therapy, but by using them more intelligently: treating and scanning when molecular evidence indicates need, and stepping back when it does not.

For hospital administrators, the value proposition is capacity and cost control without compromising outcomes. For oncologists, it is earlier, more individualised signals of residual disease, response, and relapse risk, delivered through a simple blood draw.

This post explains how ctDNA can reduce avoidable harm (toxicity, radiation burden, invasive procedures) while supporting better use of high‑cost resources in the Nordics, and, increasingly, across the EU/UK.

The problem hiding in plain sight: intensity without individual risk

In routine practice, many patients receive adjuvant chemotherapy or undergo frequent imaging based on population‑level risk features. That can be appropriate, but it also means some patients are exposed to toxicity, radiation, anxiety, and hospital visits that may not be necessary.

A key shift enabled by tumour‑informed ctDNA is precision intensity:

• Escalate follow‑up and therapy when ctDNA indicates molecular residual disease or rising tumour signal.
• De‑escalate when ctDNA is consistently negative and the relapse risk is demonstrably low.

What harms can ctDNA help us avoid?

1) Chemotherapy‑related toxicities (often long‑lasting, sometimes irreversible)

When ctDNA is used to identify who truly benefits from additional therapy, fewer patients need to be exposed to the major burdens of chemotherapy, including:

• Chemotherapy‑induced peripheral neuropathy (CIPN), which can become chronic and disabling (notably with taxanes, platinums, and vinca alkaloids).
• Cardiotoxicity, including risk associated with anthracyclines and some HER2‑based regimens/combination strategies.
• Infertility and gonadal failure, especially relevant in paediatric and AYA (adolescent and young adult) populations.
• Myelosuppression, with downstream infections, transfusions, hospitalisations, and the long‑term risk of therapy‑related MDS/AML.
• Cumulative fatigue and frailty, plus nausea, mucositis and cognitive effects, burdens that may be avoidable when no molecular residual disease is present.

2) Imaging‑related burdens and radiation exposure

Imaging remains essential, but repeated CT and PET/CT surveillance has real costs and risks:

• Cumulative radiation exposure, with a measurable (and not trivial) lifetime cancer risk, particularly in younger patients and in long surveillance programmes.
• Secondary malignancy risk and tissue damage decades later, a major concern in curative settings and childhood cancers.
• “Scanxiety”, contrast reactions, incidental findings, and the cascade of extra tests they can trigger.
• In paediatrics: sedation/anaesthesia burden for long scans (e.g., MRI protocols).

Replacing some routine imaging time points with ctDNA‑triggered imaging (scan when ctDNA rises rather than on the calendar alone) targets exactly these issues, while maintaining safety through escalation when the molecular signal changes.

3) Harms from repeated invasive monitoring procedures

In some diseases and care settings, monitoring still includes high‑burden procedures:

• Bone marrow biopsies, lumbar punctures, invasive tissue biopsies, each carrying pain, infection/bleeding risk, and sometimes sedation/OR costs.
• Extra hospital visits and time off work/school for patients and caregivers.

A blood‑based ctDNA approach can reduce reliance on some of these high‑risk procedures, particularly for monitoring and relapse assessment.

What does the evidence say about safely doing less?

Two studies illustrate why ctDNA is moving from “interesting” to “actionable”.

Stage II colon cancer: fewer patients need adjuvant chemotherapy

The randomised DYNAMIC trial demonstrated that a ctDNA‑guided adjuvant strategy reduced chemotherapy usewhile keeping outcomes essentially unchanged: 15% of patients received chemotherapy in the ctDNA‑guided arm vs 28% under standard management, with two‑year recurrence‑free survival 93.5% vs 92.4%.
Source: Tie et al., NEJM 2022
https://www.nejm.org/doi/full/10.1056/NEJMoa2200075

Direct clinical implication: fewer patients exposed to neuropathy, cytopenias, cardiotoxicity risk, fertility harm, and treatment‑related admissions, without compromising recurrence outcomes.

Metastatic breast cancer: earlier signals and fewer scans (when ctDNA is positive)

In the multicentre PDM‑MBC study using personalised, ultrasensitive ctDNA monitoring, ctDNA rose at or before radiological progression in most patients who progressed, with a median lead time of 114 days; and modelling suggested that imaging triggered by ctDNA rise could avoid a substantial portion of scans among ctDNA‑positive patients.
Source: Mouhanna et al., International Journal of Cancer 2024 

Operational implication: fewer low‑yield routine scans, better targeted imaging, and improved use of radiology capacity, highly relevant for Nordic systems facing backlogs.

Why tumour‑informed (not tumour‑naïve) matters for MRD and early recurrence

If ctDNA is to influence clinical decisions, false positives and missed disease matter.

Tumour‑informed assays track patient‑specific variants confirmed in tumour tissue, which supports both:

• Higher sensitivity for very low ctDNA levels (useful in MRD / early relapse settings), and
• Higher specificity, reducing the risk of confounding signals such as clonal haematopoiesis (CHIP).

Simsen describes this tumour‑informed vs tumour‑naïve distinction here:
https://simsendiagnostics.com/simsen-process-tumor-informed-naive

What this means for hospitals in the Nordics (and across the EU/UK)

Health benefits (what improves for patients)

A ctDNA‑enabled pathway can support:

• De‑escalation of unnecessary therapy (less toxicity, fewer acute complications).
• Earlier relapse detection at lower tumour burden, potentially allowing more effective, less intensive interventions.
• Improved quality of life, with fewer hospital visits, fewer invasive procedures, and less scan‑related stress.

Economic and capacity benefits (what improves for health systems)

For administrators, the opportunity is not “an extra test”, but pathway redesign:

• Reduced imaging volume where appropriate (and better targeting of scans when ctDNA changes).
• Lower chemotherapy utilisation in settings where ctDNA can safely guide de‑escalation (drug costs, infusion visits, supportive care).
• Fewer admissions and complications associated with overtreatment.
• Lower long‑term costs from chronic toxicities (neuropathy management, cardiac sequelae, infertility interventions, secondary malignancies).
• In paediatrics: potential reductions in anaesthesia demand tied to surveillance imaging.

Even where ctDNA introduces new direct costs (tumour profiling, panel design, serial plasma testing), the system‑level question is whether it reduces total pathway cost and burden, which the direction of evidence increasingly supports.

Making it practical: how to implement tumour‑informed ctDNA without overwhelming your lab

This is where many discussions stall, so it’s worth being concrete.

With Simsen Personal LabSuite, hospitals can implement tumour‑informed ctDNA monitoring in two main ways (depending on in‑house capacity and preference):

1. In‑house personalised panels (your lab runs the assays; support and workflows provided)
2. Full‑service monitoring (tumour profiling/panel design/plasma analysis/reporting handled externally)

In both cases, the goal is an actionable clinical output: ctDNA load, VAF, cfDNA input, and longitudinal trends, presented so it can be used in MDT discussions and follow‑up planning.

Learn more about the hospital solution here:
https://simsendiagnostics.com/simsen-personal-labsuite

A call to action: pilot, measure, scale

If you are a hospital administrator or oncologist, ctDNA monitoring is now at the point where a well‑designed implementation can answer three practical questions quickly:

1. Which patient groups benefit first (where evidence and feasibility are strongest)?
2. What can be safely reduced (chemo cycles, scan frequency, invasive monitoring)?
3. What is the net impact on outcomes, capacity, and cost?

If you are exploring tumour‑informed ctDNA monitoring, whether as an in‑house capability or via a full‑service model, we would be glad to discuss what a pragmatic pilot could look like in your setting.

Contact Simsen Diagnostics via our site to start a conversation:
https://simsendiagnostics.com/simsen-contact-us
(Or go directly to the LabSuite overview: https://simsendiagnostics.com/simsen-personal-labsuite)

Sources / further reading

• DYNAMIC trial (stage II colon cancer), NEJM 2022: https://www.nejm.org/doi/full/10.1056/NEJMoa2200075
• PDM‑MBC personalised ctDNA monitoring study (PDF): https://simsendiagnostics.com/hubfs/Integration%20of%20personalised%20ultrasensitive%20ctDNA%20monitoring.pdf?hsLang=en
• Simsen Process (tumour‑informed vs tumour‑naïve): https://simsendiagnostics.com/simsen-process-tumor-informed-naive
• Simsen Personal LabSuite (hospitals & clinics): https://simsendiagnostics.com/simsen-personal-labsuite