Biopsy Method, Needle Size Impacts NGS Success Rates in Lung Cancer

In patients with non–small-cell lung cancer (NSCLC), next-generation sequencing (NGS) has become an essential aspect of identifying the appropriate therapy, and successful NGS relies on sufficient DNA collection. A study published in JTO Clinical Research Reports found varied success rates between biopsy methods and needle sizes.

Genomic testing is strongly recommended by the National Comprehensive Cancer Network for patients with lung cancer, but only approximately 1 in 3 patients in the United States undergo successful NGS before starting therapy, the study authors noted.

The method of biopsy and analysis depends on factors such as tumor location and size as well as specialist availability, and each strategy carries risks and benefits. For the study, 4 biopsy methods were explored: CT-guided transthoracic core needle biopsy (CT-TTCN), endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA), bronchial forceps biopsy, and surgical resection.

“One factor that may impact selection of method is the probability that biomarker testing will produce the quantity and quality of the tumor sample size necessary to inform treatment decisions,” the authors wrote. “The aim of our study is to determine how selection of biopsy method impacts the availability for biomarker testing using NGS.”

Samples from a total of 285 patients with lung cancer were included in the study, which encompassed 77 CT-TTCN biopsies, 74 EBUS-TBNA biopsies, 27 bronchial forceps biopsies, and 107 surgical resections.

A total of 105 surgical resections (98.1%), 22 bronchial forceps biopsies 81.5%), 43 EBUS-TBNAs (58.1%), and 41 CT-TTCN biopsies (53.2%) led to successful NGS assays. Larger needle size for CT-TTCN biopsy was associated with a significantly higher probability of successful NGS, with 18-gauge needle biopsy showing a 90% success rate and 33.3% of 20-gauge needle biopsies leading to successful NGS.

“Others have found similar results with regard to the impact of biopsy method on biomarker success, but have not categorized success with regard to biopsy needle size,” the authors wrote. “While surgical resections and forceps biopsy are clearly the best method for obtaining tissue, not all patients have these specimens available or obtainable at diagnosis and often, needle biopsy is the preferred method based on anatomic and logistic considerations.”

Complication rates were higher in EBUS-TBNA compared with CT-TTCN, but the DNA yield was higher in EBUS-TBNA versus CT-TTCN when biopsies were taken from primary lung sites.

The most common complications associated with CT-TTCN biopsy were pneumothorax and hemorrhage, which occurred in 18.2% and 2.6% of cases, respectively. The overall rate of complications with CT-TTCN was 26%. The rate of complications when using an 18-gauge needle was 10%, versus 35.6% with a 20-gauge needle. The overall complication rate with EBUS-TBNA was 1.4%.

“Our paradoxical finding of lower complications rate with larger needles is explained by differences in the biopsy target in both groups,” the authors explained. “All 20 CT-TTCN biopsies in our series utilizing a 18-gauge needle were performed on a non-lung site, such as an adrenal gland or lymph node, which may explain the lower complication rate in the 18-gauge needle group. However, others have found the larger needles safe in lung.”

Study limitations included the retrospective nature of the analysis and the reliance on data from medical records. It was also a single-center study, meaning the physicians conducting the biopsies may not represent the broader population of clinicians and skill levels. Further research across other centers is needed to confirm the findings.

Reference

Diep R, MacDonald M, Cooper R, et al. Biopsy method and needle size on success of next-generation sequencing in non-small cell lung cancer: a brief report. JTO Clin Res Rep. Published online March 11, 2023. doi:10.1016/j.jtocrr.2023.100497