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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 and NSCLC.

Testing for ctDNA requires specialist testing kits which much be ordered in advance from the relevant GLH.

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. Referrers in our region should request kits via the 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 - 10-08-2025 23:00