Objective: To find a new method to molecular biological detection of lung cancer.
Method: The sputum specimens from 96 cases of lung cancer and other lung patients were detected for K-ras and p53 mutations by using polymerase chain reaction(PCR) and restriction fragment length polymorphism and and immunohistochemistry (IHC) techniques.
Result: 38 out of 62 sputum specimens of lung cancer patients were positive for cytology: Sensitivity was 61%. NPV (negative predictive value) was 59%; p53 was overexpressed in 48 cases: Sensitivity was 77%. NPV was 66%; k-ras was positive in 21 cases: Sensitivity was 34%, NPV 42%; The combination of conventional cytology and molecular screening(k-ras + p53) produced a sensitivity value of 92%(P < 0.05) with an NPV of 84%(P < 0.05); In 24 cases of patients whose cytology of sputum was false negative, 17 were found either p53 or k-ras positive of which 7 patients were identified to be lung cancer in the follow-up study.
Conclusion: These results suggest that detection of oncogene mutation in sputum enhanced and added to the diagnostic value of conventional cytology. It is a promising approach to early lung cancer detection and massive screening in terms of its rapidity, economy and simplicity.