Detection of p53 gene mutations in sputum samples and their implications in the early diagnosis of lung cancer in suspicious patients.
OBJECTIVE
To evaluate the value of detecting p53 gene point mutations in sputum samples and its validity and reliability as a surveillance index in the early diagnosis of lung cancer in suspicious patients.


METHODS
Sputum samples were collected from 54 cases identified as lung cancer and 114 cases identified as pulmonary benign disease. The polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) was performed for the detection of point mutations at exons 5-8 of the p53 gene, and sputum smears were also used for each sample.


RESULTS
The detected mutation rate of 55.56% (30/54) in the lung cancer group was significantly higher than that of 1.75% (2/114) in the control group (P < 0.001). In the lung cancer group, the sensitivity, specificity, and positive likelihood ratio (PLR) of p53 mutations as a diagnostic marker for lung cancer were 55.56%, 98.25% and 31.75%, respectively. Also, the detection rates were 35.19% (19/54) by smears and 55.56% (30/54) by PCR-SSCP-silver stain, respectively. The differences both in rate and consistency were statistically significant (P < 0.01 and P < 0.05, respectively). Moreover, statistical analysis showed no significant relations between p53 mutations and clinical parameters such as gender, smoking habits, histotypes and stages, but the detection rate of p53 mutations in older patients (> or = 60 years old) was significantly higher than that in younger patients (P = 0.02). One case with p53 mutations at exon 5 in the control group was confirmed to be squamous cell carcinoma after 4 years of follow-up.


CONCLUSIONS
Detection of p53 gene alterations in sputum samples by PCR-SSCP-silver stain can be used as a follow-up surveillance index for the early diagnosis of lung cancer in suspicious patients.
Wang
B
B
Department of Respiratory Diseases, Peking Union Medical College Hospital, Beijing 100730, China. wbinchao@hotmail.com
Li
L
L
Yao
L
L
Liu
L
L
Zhu
Y
Y
D000328:Adult; D000368:Aged; D005091:Exons; D005260:Female; D016158:Genes, p53; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D013183:Sputum / Q000378:metabolism*