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Circulating tumour DNA (ctDNA) tests

Circulating tumour DNA (ctDNA) tests allow for the detection of genetic changes in tumour cells (somatic testing) via blood test. The test detects DNA from cancer cells that can be found circulating in the blood. ctDNA tests are currently listed in the national genomic test directory for breast cancer, NSCLC and cancer of unknown primary.

Non-urgent advice: ctDNA testing for CUP

From July 2026, patients with cancer of unknown primary (CUP) can be referred for circulating tumour DNA (ctDNA) testing.

ctDNA testing uses a simple blood test to detect tumour DNA circulating in the bloodstream. For patients with CUP, this can help:

  • Identify the likely tissue of origin
  • Detect clinically actionable genomic alterations
  • Support diagnosis, treatment decisions and access to clinical trials

Testing for ctDNA requires specialist testing kits which much be procured by your Trust in advance of testing. Find out more

ctDNA tests detect genetic changes within cancer cells (somatic testing) they do not detect inherited cancer risk mutations that may be present in all cells (germline testing).

These tests should be used to inform diagnosis and treatment of patients with cancer, not to assess inherited cancer risk.

ctDNA tests are not currently performed by East Genomics. For information about testing please visit Marsden360 website or email Marsden360@rmh.nhs.uk.

Breast cancer (M3.13)

Testing can be used to detect ESR1, PIK3CA, AKT1 and PTEN variants.

ESR1 can be used to guide treatment decisions for treating oestrogen receptor-positive, HER2-negative advanced breast cancer with an ESR1 mutation after endocrine treatment. Patients must have completed at least 12 months of endocrine treatment plus a CDK 4 and 6 inhibitor.

PIK3CA/AKT1/PTEN can be used to guide treatment decisions for treating adults with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer after endocrine treatment.

Non-small cell lung cancer (M4.14)

Testing can be used to detect a range of genetic variants including small variants in EGFR, ALK, BRAF, KRAS, MET (exon 14 skipping) and structural variants in ROS1, RET, ALK, NTRK1, NTRK2, NTRK3, MET (exon 14 skipping).

Eligible patients should have radiologically suspected stage III/IV lung cancer, likely unsuitable for curative intent surgery or radical radiotherapy and an ECOG Performance Status between 0-3. Or they should have a confirmed new histological diagnosis of NSCLC, previously untreated for advanced disease where diagnostic molecular testing has failed, and an alternative option would be to re-biopsy.

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This document was correct at the time of printing - 22-07-2026 07:28