Clinical impact of EGFR and KRAS mutations in surgically treated unifocal and multifocal lung adenocarcinoma.

Background: Epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma (KRAS) are the two most common oncogenic drivers in lung adenocarcinoma, and their roles still need further exploration. Here we aimed to compare the clinical impact of EGFR and KRAS mutations on disease progression in resected unifocal and multifocal lung adenocarcinoma.

Methods: Clinicopathologic and genomic data were collected for patients who underwent resection of lung adenocarcinoma from 2008 to 2022 at Stanford University Hospital. Retrospective review was performed in 241 patients whose tumors harbored EGFR (n=150, 62.2%) or KRAS (n=91, 37.8%) mutations. Clinical outcome was analyzed with special attention to the natural history of secondary nodules in multifocal cases wherein the dominant tumor had been resected.

Results: We confirm that compared with EGFR mutations, patients with KRAS mutations had more smokers, larger tumor size, higher TNM stage, higher positron emission tomography (PET)/computed tomography (CT) standard uptake value max, higher tumor mutation burden, and worse disease-free survival and overall survival on univariate analysis. For patients with multifocal pulmonary nodules, the median follow-up of unresected secondary nodules was 55 months. Secondary nodule progression-free survival (SNPFS) was significantly worse for patients with KRAS mutations than those with EGFR mutations (mean 40.3±6.6 vs. 67.7±6.5 months, P=0.004). Univariate analysis showed tumor size, tumor morphology, pathologic TNM stage, and KRAS mutations were significantly associated with SNPFS, while multivariate analysis showed only KRAS mutations were independently associated with worse SNPFS (hazard ratio 1.752, 95% confidence interval: 1.017-3.018, P=0.043).

Conclusions: Resected lung adenocarcinomas with KRAS mutations have more aggressive clinicopathological features and confer worse prognosis than those with EGFR mutations. Secondary pulmonary nodules in multifocal cases with dominant KRAS-mutant tumors have more rapid progression of the secondary nodules.