Reporting of molecular test results from cell-free DNA analyses: expert consensus recommendations from the 2023 European Liquid Biopsy Society ctDNA Workshop.

The implementation of circulating tumor DNA (ctDNA) in the diagnostic routine may enable non-invasive predictive biomarker testing and treatment optimization in patients who lack a suitable tumor specimen, have failed previous molecular analysis or are clinically ineligible for (re-)biopsy procedures. As the interpretation and reporting are more complex for ctDNA than conventional tissue-based NGS, there is a need for specific guidelines. These will offer support for the reporting of ctDNA test results and will facilitate optimal communication of liquid biopsy findings between diagnostic laboratories and the medical oncology team. Aiming to generate guidelines based on real-world experiences and broad perspectives, we organized a European Liquid Biopsy Society (ELBS) ctDNA workshop, in which forty-four experts and key stakeholders from different molecular diagnostics laboratories, oncology and pathology departments, as well as an IVDR specialist, convened to address significant challenges associated with the reporting of liquid biopsy test results. This report delineates the resulting consensus recommendations for ctDNA test reporting with underlying rationale and background information.