RESUMO
<p><b>BACKGROUND</b>To investigate the diagnostic value of chest CT scan combined with telomerase activity and p16 gene methylation from exfoliated cells of sputum in 55 cases of solitary pulmonary nodules (SPN; ≤30 mm)suspected early peripheral lung cancer.</p><p><b>METHODS</b>The sputum specimens from 34 cases of cancer nodules and 21 cases of benign lesion were detected for telomerase activity by TRAP-PCR-ELISA and p16 gene methylation by PCR-based methylation analysis.</p><p><b>RESULTS</b>The qualitative diagnostic accuracy of CT scan was 61.8%(34/55) for SPN provided by pathology. Cytology analysis of sputum was positive in 13 cases (38.2%). Telomerase activity was positive in 29 cases: sensitivity was 79.4%, specificity was 90.5%, accuracy was 83.6%; p16 gene methylation was found in 11 cases: sensitivity was 32.4%, specificity was 100.0%, and accuracy was 58.2%. The sensitivity was increased to 86.1% by combination of telomerase activity and p16 gene methylation. Compared with nodules without malignant CT signs, expression of telomerase activity and p16 methylation of SPN with malignant CT signs (lobulation or spiculate protuberance or spicule sign) had a significant difference (P < 0.01).</p><p><b>CONCLUSIONS</b>The results suggest that chest CT scan combined with telomerase activity and p16 gene methylation detection in sputum for patients with peripheral lung cancer may enhance the diagnostic value of radiology and conventional cytology.</p>
RESUMO
<p><b>BACKGROUND</b>To investigate the methylation and deletion of p16 gene and its diagnostic value in non-small cell lung cancer.</p><p><b>METHODS</b>A total of 50 lung cancer tissues and 54 normal lung tissues were examined for p16 gene methylation in exon 1 and deletion in exon 2 by PCR based methylation analysis and duplex PCR respectively.</p><p><b>RESULTS</b>Out of 50 lung cancer tissues, 16 were positive for the p16 gene exon 1 methylation (32.0%), and 14 for the p16 gene exon 2 deletion (28.0%). However, in 54 cases of normal lung tissues, only 2 showed the p16 gene exon 1 methylation(3.7%), and none showed the p16 gene exon 2 deletion. There were significant differences in methylation rate (Fisher's exact= 0.000 ) and deletion rate (Fisher's exact= 0.000) between the two groups.</p><p><b>CONCLUSIONS</b>The methylation and deletion may be important mechanisms for p16 gene inactivation in non-small cell lung cancer. The detection of p16 gene status may contribute to the diagnosis of lung cancer.</p>
RESUMO
<p><b>BACKGROUND</b>To detect the micrometastases status in peripheral blood and regional lymph nodes of lung cancer patients by reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>METHODS</b>CK19 mRNA expression in peripheral blood and regional lymph nodes was detected in 78 patients with lung cancer, and 30 patients with pulmonary benign lesions and 10 healthy volunteers as controls by RT-PCR. Meanwhile, all lymph nodes were also examined by traditional pathological method.</p><p><b>RESULTS</b>The positive rate of CK19 mRNA expression was 38.5% in peripheral blood of lung cancer patients, and 6.7% in patients with pulmonary benign lesions (6.7%) (Chi-square=10.505,P=0.001). No positive CK19 mRNA expression was found in peripheral blood of 10 healthy volunteers. The positive rates of CK19 mRNA of lymph nodes were 36.9% and 0 in lung cancer patients and pulmonary benign disease patients respectively (Fisher's exact=0.014). In lung cancer group, the metastatic rate of lymph nodes was 17.9% by traditional pathological examination, which was much lower than that by RT-PCR (Chi-square=7.664, P=0.006).</p><p><b>CONCLUSIONS</b>RT-PCR amplification of CK19 mRNA is an sensitive method to detect early haematogenous and regional lymph nodes dissemination of cancer cells for patients with lung cancer. This method may lead to an earlier diagnosis and treatment of patients with subclinical metastasis in circulation and regional lymph nodes.</p>