Predictive advantage of a cell type classification for pulmonary adenocarcinoma coupled with data for p53, K-ras and EGFR alterations

Prognostic value of K-RAS mutations in patients with non-small cell lung cancer: a systematic review with meta-analysis

K-RAS gene mutations have been found in 20-30% of non-small cell lung cancer and occur most commonly in adenocarcinoma, however, there was no definitive conclusion about the prognostic role of K-RAS mutations in NSCLC. Herein we performed a systematic review of the literatures with meta-analysis to assess K-RAS mutations' prognostic value in NSCLC. After a methodological assessment, survival data from published studies were aggregated. Combined hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were calculated in terms of overall survival. 41 trials (6939 patients) were included in the analysis, the overall HR was 1.45 (95% CI: 1.29-1.62), showing that K-RAS mutations have an unfavorable impact on survival of patients with NSCLC. Then a subgroup analysis was performed about ethnicity, the combined HR was 1.97 (95% CI: 1.58-2.44) for Asians, and 1.37 (95% CI: 1.25-1.5) for non-Asians. In subgroup analysis of histology, the HR was 1.39 (95% CI: 1.24-1.55) for adenocarcinoma, suggesting that K-RAS mutations were correlated with shortened survival for adenocarcinoma. When the subgroup analysis was conducted according to disease stage, K-RAS mutations were poor prognostic factors in early stages: stage I (1.81; 95% CI: 1.36-2.39) and stage I-IIIa (1.68; 95% CI: 1.11-2.55), but not in advanced stage (IIIb-IV) (1.3; 95% CI: 0.99-1.71). At last, in subgroup analysis about test methods, all of the four methods: PCR-MSOP (1.73; 95% CI: 1.35-2.2), PCR-DGGE (1.27; 95% CI: 1.01-1.62), PCR-RFLP (1.88; 95% CI: 1.42-2.49) and PCR-seq (1.34; 95% CI: 1.14-1.58) showed statistically significant impact on survival of NSCLC patients. In conclusion, this meta-analysis suggests that K-RAS mutations are associated with a worse overall survival in patients with NSCLC, especially in patients with adenocarcinoma and early stage.

KEAP1 gene mutations and NRF2 activation are common in pulmonary papillary adenocarcinoma

Distinctive histological variants of lung cancer are increasingly recognized to have specific genetic changes that affect tumor biology and response to therapy. In this study, we evaluated true papillary adenocarcinoma of the lung, proposed as a distinct diagnostic category with relatively poor response to therapy, to determine whether these tumors also have specific molecular alterations that would affect sensitivity to chemotherapy. Specifically, we measured protein levels of P53, excision repair cross-complementation 1 (ERCC1) and ribonucleotide reductase M1 (RRM1) by immunohistochemistry and evaluated the Kelch-like erythroid cell-derived protein with cap-n-collar homology (ECH)-associated protein 1 (KEAP1) gene for mutations, correlating mutations of this gene with total and nuclear expression of the nuclear factor erythroid-2-related factor 2 (NRF2). We found high levels of P53 in 23 of the 55 specimens (41.8%), similar to the rate of P53 gene mutations observed in general for pulmonary adenocarcinoma, and levels of ERCC1 and RRM1 also showed distributions similar to those reported generally for non-small lung cell cancer (NSCLC). However, KEAP1 alterations were observed at a significantly higher frequency in papillary adenocarcinoma tumors (60%) than what has been reported previously for NSCLC (3-19%). These mutations of KEAP1 were associated with increased nuclear accumulation of NRF2 in tumors, as expected for functional alterations. Thus, high rates of KEAP1 mutations and NRF2 overexpression in true papillary adenocarcinoma could be related to poor prognosis and chemotherapy resistance. Furthermore, this distinctive molecular characteristic supports the recognition of true papillary adenocarcinoma as a diagnostic entity.