Blood Tests for Cancer Recurrence: How CTC monitoring could support follow-up care
Completing cancer treatment is a significant milestone. But for many patients, the period that follows is defined not by relief, but by anxiety- wondering whether the cancer will come back, and whether they will know in time if it does. This is something which can last for the rest of their lives.
Current follow-up care typically involves periodic clinical reviews and imaging. These are important. They are also, in many cases, insufficient to detect recurrence at the earliest possible biological stage. And we know that early detection can save lives.
Circulating tumour cell (CTC) monitoring is looking to change this. Here is how.
The surveillance gap
When a patient finishes primary treatment, they enter a surveillance phase. The goal is to detect any sign that the cancer has returned as early as possible. The challenge is that standard surveillance tools are designed to detect structural change. Imaging can show a mass that has grown large enough to be visible. A clinical examination can identify symptoms that have already developed. By the time these tools detect recurrence, the biology has often been signalling for some time.
What CTC monitoring adds
Circulating tumour cells are shed by cancer cells into the bloodstream. In a patient who has completed treatment, the presence of CTCs — and the trajectory of CTC counts over time — provides a biological signal that can precede structural change.
Research in breast cancer and other tumour types has demonstrated that rising CTC counts during post-treatment surveillance are associated with an increased risk of clinical recurrence. In some studies, CTC changes have preceded imaging-detectable relapse by weeks to months.
Earlier detection of recurrence opens up earlier intervention. And earlier intervention, in most cancer types, is associated with more treatment options and better outcomes.
What this might look like
• A blood draw at regular intervals — typically every two to three months, aligned with existing follow-up appointments
• CTC enumeration from the blood sample — counting the number of circulating tumour cells present
• Tracking changes over time — a stable or a declining low count is reassuring; a rising count warrants further investigation
• Integration alongside standard imaging and clinical review, not as a replacement
The patient experience
For patients, the practical reality of CTC monitoring is very different from other surveillance tools. A blood draw takes minutes, requires no preparation, and can be carried out at a routine appointment. For patients already carrying the psychological burden of post-treatment uncertainty, regular access to a biological data point has real value.
Where Frontier Diagnostics fits in
At Frontier Diagnostics, post-treatment monitoring from Stage 1 to Stage 4 tumours is one of the clearest potential applications of our CTC detection technology. We believe the surveillance gap in cancer care is real, and that liquid biopsy- specifically whole-cell CTC analysis- could be one of the most powerful tools available to close it.
