In this study, we found that the levels of KRAS or EGFR mutations in plasma were quite different from patient to patient before surgery, but most EGFR and KRAS mutations in lung cancers could be detected in patient plasma; and the recurrence rates between patients with and without detectable KRAS and EGFR mutation in the plasma at 30 days after surgery were significant. The gene discussed is EGFR; the disease is lung cancer.