Mutation profile and programmed death ligand 1 status of patients with non-small cell lung cancer diagnosed with "adenocarcinoma" and "non-small cell carcinoma favor adenocarcinoma".

BACKGROUND: The terminology for lung cancer diagnosis in small biopsies was adopted in the 2015 World Health Organization classification. If non-small cell lung cancer (NSCLC) has no clear adenocarcinoma (AD) or squamous cell carcinoma morphology, the tumor is further classified based on mucin or immunohistochemical staining as NSCLC favor AD (NFAD), NSCLC favor squamous cell carcinoma, or NSCLC not otherwise specified. Since this new term was defined, the difference between AD and NFAD has not yet been fully explored. This study aimed to examine the differences in clinical background, gene alteration frequency, and programmed death ligand 1 (PD-L1) expression. METHODS: We included patients diagnosed with AD or NFAD with small samples, and who underwent testing with the Oncomine Dx target test between August 2019 and April 2023 in Kanagawa Cancer Center. RESULTS: This study comprised 268 patients. A total of 96 patients underwent surgery after AD or NFAD diagnosis. The clinical stage was more advanced and pathological N0 was lower in NFAD than in AD. The pathology of the surgical specimens revealed that solid predominant AD was significantly more common in NFAD than in AD (p < 0.001). In both AD and NFAD, EGFR mutation was the most frequent gene alteration, followed by KRAS mutation. The frequency of EGFR mutations was significantly higher in AD than in NFAD. PD-L1 expression was significantly higher in NFAD than in AD (p < 0.001). CONCLUSION: This study shows a clear difference between AD and NFAD in terms of cancer progression, pathological features of the main tumor, genetic characteristics, and PD-L1 expression.

Comparison of next-generation sequencing and cobas EGFR mutation test v2 in detecting EGFR mutations.

BACKGROUND: As the number of genetic mutations that must be tested increases, the Oncomine Dx Target test (ODxTT), which can simultaneously detect multiple cancer-related genes is becoming the main test used in preference to single-molecule testing. In this study, we evaluated the performance of ODxTT and cobas EGFR mutation test v2 (cobas EGFR), one of the single-molecule tests, in detecting EGFR mutations. METHODS: Samples from 211 patients diagnosed with NS-NSCLC were tested simultaneously or sequentially with the cobas EGFR mutation test and ODxTT. We compared the success and detection rates of both tests and evaluated their equivalence by determining the concordance rate and k-coefficient of both tests. RESULTS: The success rate in detecting EGFR mutations was 95.7% for ODxTT and 100% for cobas EGFR. EGFR mutations were detected in 26.5% of samples with ODxTT and in 28.0% with cobas EGFR. For the 200 samples successfully analyzed with both tests, the concordance rate and k-coefficient were 97.5% and 0.938, respectively. ODxTT failed to detect two exon 19 deletion mutations (p.E746_P753delinsVS and p.E746_P753delinsLS), and cobas EGFR failed to detect three instances of an exon 19 deletion (p.L747_P753delinsS), L861R, and an exon 20 insertion. DISCUSSION: The success rate of ODxTT is slightly inferior to that of cobas EGFR. ODxTT shared a high concordance rate and k-coefficient with cobas EGFR in detecting EGFR mutations, but discordant results between the two tests were observed in a few cases, mainly due to the difference of detectable EGFR variants.