Clinical significance of the detection of the homozygous deletion of P16 gene in malignant pleural effusion

Abstract

Objective: To assess the role of the p16 gene exon 2 homozygous deletion in malignant pleural effusions. Methods: The homozygous deletion of p16 gene was determined in 34 pleural effusions due to non-small cell lung cancer (NSCLC) and in 21 cases with tuberculous pleuritis by polymerase chain reaction (PCR), compared with the determination of exfoliated cytology in the same specimens. Results: The PCR analysis showed that the homozygous deletion of p16 exon 2 was identified in 15 of 34 malignant pleural effusions (44.11%), including 8 negative cytology and it was not found any tuberculous pleural effusions. The exfoliated cytology of pleural effusion was positive in 19 of 34 malignant cases (55.88%). By combining two methods, the diagnostic sensitivity was enhanced, from 55.88% (19/34) to 79.41% (27/34), whose positive rate was higher than only determination of p16 exon2 homozygous deletion or exfoliated cytology in malignant pleural effusions (p<0.001, p<0.05 respectively). Conclusion: Our data suggested that combining the examination of exfoliated cytology and homozygous deletion of p16 gene exon2 in pleural effusion can recruit and enhance the diagnostic value of pleural effusion cytology. The detection of the homozygous deletion of the p16 gene in pleural effusion may be a useful adjunct to the cytological and histological examinations of pleural effusion. In cases of undiagnosed exudative pleural effusion with a high clinical suspicion for malignancy, it is reasonable to examine the homozygous deletion of pleural fluid p16 gene. With p16 gene homozygous deletion in pleural effusion, it may be strongly highly likely to be malignant and have a higher metastatic potential. © 2007 The Japanese Society of Internal Medicine.