How to express tumor markers in bronchoalveolar lavage

Bronchoalveolar lavage (BAL) is a fundamental technique in the diagnosis of different respiratory diseases including lung cancer. Tumor marker values can be determined in the BAL fluid, but controversy still exists about how to express the results.

The aim of this study was to determine the best method of expressing tumor markers in BAL, either referring to total proteins or volume of fluid recovered.

A prospective, randomized, non-blind study was carried out. Seventy-six patients (72 men and 4 women) diagnosed with lung cancer and 17 subjects without respiratory disease were included. BAL was performed in all patients and the fluid retrieved was divided into two fractions: a bronchiolar fraction (F0) and an alveolar fraction (F1). Five tumor markers: cytokeratin fragment 19 (CYFRA 21-1), squamous cell carcinoma antigen (SCC), tissue polypeptide antigen (TPA), tissue polypeptide-specific antigen (TPS) and neuron-specific enolase (NSE) as well as total protein were measured in both fractions. The concentrations were expressed in relation to the volume of BAL fluid recovered (ng or mU/mL) and in milligrams of total protein of lavage fluid (ng or mU/mg TP). The SPSS 11.01 software was used for statistical analysis. Mann-Whitney U test and ROC curves were developed when significant differences were found.

We found significant differences in the CYFRA 21-1 values in the two BAL fractions and in both ways of expressing its concentration; in SCC in F1 expressed in ng/mg TP; in TPA in F0 expressed in mU/mg TP; in TPS in both fractions expressed in mU/mg TP, and in NSE in both fractions in ng/mg TP. The markers that best differentiated tumors from controls (ROC curves) were CYFRA 21-1 in F0 and NSE in both fractions in ng/mg TP.

Our study demonstrates that the concentrations of tumor markers in BAL expressed in relation to total protein were more effective than if expressed in mL of BAL fluid collected.