PURPOSE: The diagnosis of malignant pleural effusion is clinically important because the prognosis of patients with malignant pleural effusion is poor and similar to patients with stage IV disease. But, the diagnosis will be difficult if cytologic testing is negative and the pleural effusion is transudate and nonbloody exudate. This study was performed to investigate whether aberrant methylation of p16 and retinoic acid receptor β 2 (RARB2) gene in pleural fluid is useful for the diagnosis of malignant pleural effusions.
METHODS: Pleural effusions collected from 26 lung cancer patients of a biopsy-proven pleural invasion were investigated for the aberrant promoter methylation of p16 and RARB2 using a methylation-specific PCR. Pleural fluid was obtained by thoracentesis or chest tube, and then DNA was extracted. After DNA was modified by treatment with sodium bisulfate, methylation-specific PCR (MSP) was done.
RESULTS: 19 cases were male patients and 7 cases were female. Histologic types were 12 adenocarcinomas, 7 small cell carcinomas, 6 squamous cell carcinomas, and 1 non-classifiable non-small cell lung cancer(NSCLC). Aberrant methylation of p16 and RARB2 gene were noted in 7 cases (26.9%) and 12 cases (46.1%) respectively. Together with 2 genes, aberrant methylations were detected in 15 cases (57.7%). In adenocarcinoma, squamous cell carcinoma, small cell carcinoma, and NSCLC aberrant methylations were detected in 8 out of 11 (72.7%), 3 out of 5 (60%), 3 out of 7 (42.9%), and 0 out of 1 (0%) cases respectively.
CONCLUSION: This investigation demonstrates that detection of aberrant methylation of p16 or RARB2 gene showed relatively low sensitive methods to diagnose malignant effusions.
CLINICAL IMPLICATIONS: But it also suggests if multiple genes are used for specific types of histology the results would be better.
DISCLOSURE: Junghun Huh, No Financial Disclosure Information; No Product/Research Disclosure Information