In conclusion, with the main advantages of CEA values, namely, low cost, convenient detection, and accessibility of using a standard personal computer to calculate the sensitive CEA kinetic, the serum CEA levels should be observed during the bevacizumab-based maintenance treatment in patients with metastatic NSCLC to predict early disease progression and subsequently to optimize and individualize the treatment by modifying the therapeutic regimen. The gene discussed is CEACAM5; the disease is non-small cell lung carcinoma.