[Relevance of circulating tumor DNA in lung cancer: A case report]
K Amrane1, G Le Gac2, R Descourt1
1Institut de cancérologie et d'hématologie, hôpital Augustin-Morvan, CHRU de Brest, 2, avenue du Maréchal-Foch, 29000 Brest, France.
Introduction:
The identification of an activating mutation of the gene encoding the epidermal growth factor receptor (EGFR) is a predictive factor of effectiveness of tyrosine kinase EGFR inhibitors (TKIs). In advanced stages of the disease, however, this identification is difficult due to the invasiveness of the biopsy and the small size of tumor samples. In that context, liquid biopsies could be useful.
Clinical Case:
We report the case of a 79-year-old woman suffering from metastatic lung cancer. The molecular analysis of bronchial biopsy for the EGFR gene was not informative due to the low quantity and the poor quality of the extracted DNA. The poor condition of the patient and her refusal to tissue sampling did not allow us to practice another invasive biopsy. The analysis of the tumor DNA circulating (cDNA) allowed to detect exon 19 deletion and to propose her an TKI with in the outcome sustained response.
Conclusion:
Circulating DNA analysis allows the identification of activating mutations of the EGFR gene in pulmonary adenocarcinomas. It is useful for weakened patients and in case of failure or inability of tumor biopsies. Initiation of EGFR TKI is possible on the basis of this result, as stated in the marketing authorization of gefitinib.
Insights
Liquid biopsies can detect epidermal growth factor receptor (EGFR) mutations in lung cancer when tissue biopsies fail. This enables timely treatment with EGFR tyrosine kinase inhibitors (TKIs) for improved patient outcomes.
Area of Science:
- Oncology
- Molecular Diagnostics
- Genetics
Background:
- Activating mutations in the epidermal growth factor receptor (EGFR) gene predict response to EGFR tyrosine kinase inhibitors (TKIs).
- Identifying these mutations is challenging in advanced lung cancer due to invasive tissue biopsies and small sample sizes.
- Liquid biopsies offer a less invasive alternative for molecular profiling.
Observation:
- A 79-year-old woman with metastatic lung cancer had non-informative bronchial biopsy results due to poor DNA quality.
- The patient's poor health and refusal of further invasive procedures precluded repeat tissue sampling.
- Analysis of circulating tumor DNA (ctDNA) successfully identified an EGFR exon 19 deletion.
Findings:
- Circulating DNA analysis is effective for identifying EGFR mutations in pulmonary adenocarcinoma.
- This method is particularly valuable for patients who are too frail for invasive biopsies or when tissue sampling fails.
- EGFR TKI therapy can be initiated based on ctDNA results, as supported by gefitinib's marketing authorization.
Implications:
- Liquid biopsies provide a crucial tool for personalized medicine in lung cancer, especially for vulnerable patients.
- Non-invasive molecular testing can expedite treatment decisions, improving therapeutic efficacy.
- This approach broadens the applicability of targeted therapies like EGFR TKIs in advanced lung cancer.
