Clinical usefulness of cancer antigen 125 biomarker for tuberculosis diagnosis: experience in Cali, Colombia

Introduction: Diagnosing extra-pulmonary tuberculosis (EPTB) is a challenge for physicians. It has been suggested that cancer antigen 125 (CA-125), which is produced by mesothelial cells, may be an EPTB diagnostic biomarker. Objective: To describe serum CA-125 levels behavior in patients with TB treated in a referral university hospital located in Cali, Colombia. Materials and methods: A cross-sectional study was conducted in 99 TB patients with CA-125 measurements (U/mL) made before TB treatment was started, and treated at Fundación Valle del Lili between 2007 and 2016. Cases were classified as pulmonary TB (PTB) (n=33) or EPTB (n=66). A bivariate analysis was performed to compare the variables of interest (sociodemographic, clinical, and laboratory findings data) between EPTB and PTB groups, and to determine differences between patients with CA-125 positive results and those with negative results in relation to mortality. Results: Elevated CA-125 levels were reported in 55 patients (55.56%). Positive CA-125 results (>35 U/mL) were more frequent in the EPTB group (59.09% vs. 48.48%). In the EPTB group, positive results were found in tuberculous serositis cases (100% pericardial TB, 68.42% peritoneal TB and 66.66% pleural TB), and in 66.66% of miliary TB and TB of the spine cases, respectively. Also, 15 TB infection-related deaths were reported in the follow-up period (n=66), of which 13 had a CA-125 positive result, finding a significant difference with those with negative results (p=0.021), however 47.05% of the surviving patients also had a positive result. Conclusions: Most of tuberculous serositis, miliary and TB of the spine cases showed elevated CA-125 levels before starting TB treatment. CA-125 may prove to be useful for prognostic purposes in these patients.