[Application of puncture tissue rinse solution in the detection of EGFR gene mutations in non-small cell lung cancer].

OBJECTIVES: Precision targeted therapy for non-small cell lung cancer (NSCLC) relies on molecular classification based on gene mutations. Detection of driver gene mutations, particularly epidermal growth factor receptor (EGFR) mutations, is crucial for treatment decision-making in locally advanced and metastatic NSCLC. Currently, clinical sources of nucleic acids include formalin-fixed paraffin-embedded (FFPE) tumor tissues, cytological specimens from centrifuged pleural effusion, blood, and circulating free DNA in body fluids such as pleural effusion supernatant. This study aims to extract nucleic acids from the double-distilled water rinse solution of lung biopsy specimens for gene mutation detection, to evaluate the feasibility of this nucleic acid source, and to analyze the concordance between its detection results and those obtained from tissue-based next-generation sequencing (NGS), thereby providing a basis for subsequent pathological diagnosis and treatment.

METHODS: Female patients clinically diagnosed with NSCLC and admitted to the Department of Oncology, the Second Xiangya Hospital of Central South University were included. CT-guided percutaneous lung biopsy was performed. Biopsy tissues were processed into paraffin-embedded sections for NGS testing. Meanwhile, DNA was extracted from the double-distilled water rinse solution of biopsy tissues, and EGFR gene mutations were detected using the super amplification refractory mutation system-polymerase chain reaction (Super-ARMS). Samples with remaining DNA meeting quality control standards were further subjected to NGS. The concordance between gene mutation results from the rinse solution and those from corresponding FFPE tissue samples was analyzed. In addition, DNA concentrations from percutaneous biopsy specimens and from the rinse solution of the puncture needle were measured and compared.

RESULTS: Among 29 NSCLC patients, Super-ARMS of the biopsy tissue rinse solution detected 19 EGFR mutation-positive cases and 10 negative cases, while NGS of FFPE tissue samples detected 20 positive cases and 9 negative cases. Compared with tissue NGS, the rinse solution Super-ARMS showed a sensitivity of 95%, specificity of 100%, positive predictive value of 100%, negative predictive value of 90%, and an overall accuracy of 96.5%. In 6 cases, DNA from the rinse solution met quality control standards after Super-ARMS and was further analyzed by NGS, showing 3 EGFR mutation-positive and 3 negative cases. These results were completely consistent with those obtained by Super-ARMS and were concordant with tissue-based NGS results. The turnaround time for EGFR mutation detection using rinse solution Super-ARMS was 1-2 days, compared with 7 days for NGS using rinse solution DNA and 14-15 days for NGS using FFPE tissue samples. In 3 paired NSCLC samples, the DNA concentration of tissue rinse solution was higher than that of the puncture needle rinse solution.

CONCLUSIONS: TDNA extracted from the double-distilled water rinse solution of CT-guided percutaneous lung biopsy specimens can serve as a rapid and efficient nucleic acid source for NSCLC genotyping, enabling earlier support for clinical diagnosis and treatment.