KRAS and adenocarcinoma: KRAS mutations were detected in 29% of patients (n = 124), with prevalence varying significantly across race/ethnicity (higher in non-Hispanic White and lower in Asian patients), stage (higher in stages I-III and lower in stage IV), histology (higher in adenocarcinomas and lower in squamous cell tumors), and smoking status (higher in former and current smokers) (Table 2).