In non-small cell lung cancer, a KRAS mutation is associated with a better prognosis: True or False?

• A. True
• B. False
• C. Unproven
• D. Only in combination with EGFR mutation

Answer: (B)

KRAS mutations in non-small cell lung cancer are generally a negative prognostic indicator, not a sign of better outcomes. An activating KRAS mutation keeps the RAS-MAPK signaling pathway running, which promotes tumor growth and can be associated with more aggressive disease. Clinically, KRAS-mutant NSCLC has historically shown poorer responses to some therapies and shorter overall and progression-free survival compared with KRAS wild-type tumors. While newer KRAS-targeted therapies (like some G12C inhibitors) are improving options for specific subgroups, the overall relationship is not that a KRAS mutation signals a better prognosis.