CA-125 in the Diagnosis of Pulmonary Tuberculosis.

Dear Editor: I have read with interest the article published by Ozsahin et al. (1) focused on the validity of the cancer antigen-125 (CA-125) in the differential diagnosis of active pulmonary tuberculosis (TB). In accordance with a previous study by Yilmaz et al. (2), they reported higher serum CA125 levels in active pulmonary TB than in inactive pulmonary TB. However, the authors found lower sensitivity and specificity values, and drew attention to the increased CA125 level in patients with other pulmonary pathologies confused with TB. It seems plausible to suggest that TB must be considered in the differential diagnosis of patients with elevated serum CA-125 concentration; however, further welldesigned studies are needed to define the precise role of CA125 in the diagnosis and follow-up process of TB. CA-125 is primarily used as a tumor marker for the diagnosis of ovarian carcinoma; however, it is known to increase in various non-malignant inflammatory conditions. The clearest evidence of the association between CA-125 and TB is seen in the cases of peritoneal TB exhibiting highly elevated serum CA-125 levels. A retrospective review of 22 cases of peritoneal TB showed that these cases had elevated CA-125 levels up to 2,021 U/ml (3). These cases represent an important diagnostic problem because it may lead to misdiagnosis as ovarian carcinoma. Furthermore, serum CA-125 levels were studied in patients with tuberculous peritonitis in a casecontrol study by Mas et al. (4), and were found to be elevated in all patients with tuberculous peritonitis; there was also a significant decrease after treatment. The authors concluded that serum CA-125 level might be used as an effective marker in the diagnosis and follow-up of peritoneal TB. Another interesting study by Kalantri et al. (5) was carried out to evaluate CA-125 levels in conditions associated with pleural effusion and ascites. Their data showed raised CA125 levels in most of the cases of ascites and pleural effusion, both transudates and exudates, irrespective of the pathology. However, the tuberculous ascites cases had higher CA-125 levels compared to tuberculous pleuritis. Their findings showed that both peritoneum and pleural epithelium have the capacity to secrete CA-125, and the secretion occurs following inflammation or mechanical distress. However, they claimed that pulmonary TB as a closed lesion without involvement of the pleural epithelium does not evoke high CA-125 release. In conclusion, a vast majority of evidence suggests that CA-125 is found increased in tuberculous peritonitis. Nevertheless, the validity of CA-125 is not clear in pulmonary TB without pleural epithelium involvement. The findings reported to the present encourage the further evaluation of this tumor marker in clinical trials to clarify its application in both the diagnosis and follow-up process of this disease that remains highly fatal worldwide.