Objective: To evaluate clinical and demographic characteristics and the results of cytotoxic treatments of KRASG12C, KRASother, and next-generation sequencing (NGS) panel negative patients. Methods: NGS data of 1264 patients with non-small cell lung cancer were retrospectively evaluated. Among these patients, the mutation distributions of 1081 patients with metastatic lung adenocarcinoma were analyzed. A total of 150 patients with negative NGS panel or mutant KRAS followed up in our clinic were included. Clinical features, overall survival, first-line chemotherapy responses, and progression-free survival of NGS panel negative, KRASG12C, and KRASother groups were compared. Results: In 1081 patients who underwent NGS from tumor tissue with the diagnosis of metastatic lung adenocarcinoma, 296 (27%) NGS panel negative and 276 (26%) KRAS mutant patients were detected. Among these patients, 150 patients whose data were available were 71 (47.3%) NGS panel negative, 54 (36%) KRASother, and 25 (16.7%) KRASG12C. Clinical features, brain metastasis, and first-line chemotherapy response were similar among groups. Bone metastases were detected more often in the NGS panel negative group (p = 0.03). The median follow-up was 8.4 months. Overall, 107 deaths had occurred at the time of analysis. There was no difference in overall survival (p = 0.56) or progression-free survival (p = 0.71) among NGS panel negative, KRASother, and KRASG12C patients. Conclusion: There is no difference in overall survival, first-line chemotherapy response, or progression-free survival among patients with NGS panel negative, KRASG12C, or KRASother metastatic lung adenocarcinoma. Bone metastases were observed more frequently in the NGS panel negative group.