The relevance of bronchoalveolar lavage fluid analysis for lung cancer patients.

Introduction: Lung cancer is a serious malignant disease with poor prognosis. The methods for improving early recognition and markers of predictive value are widely investigated. Bronchoalveolar lavage (BAL) is a valuable method of respiratory tract investigation. Currently, BAL is rarely used for tumor diagnosis, but for ruling out differential diagnosis, due to its poor sensitivity. The new indication for BAL fluid analysis is evaluation of local immune reaction in lung cancer patients and description of tumor microenvironment (TME). A literature search was performed in bibliography bases from the time of the introduction of BAL in the diagnosis of lung diseases. We analyzed our prior original studies with the bibliography.Area covered: The usefulness of BAL in the diagnosis of peripheral spread of malignant diseases and in the evaluation of TME in lung cancer, as well as a role of BAL in the diagnosis of checkpoint inhibitor pneumonitis is presented. Commentary concerning methodology of BALF analysis in lung cancer is included.Expert opinion: It seems that in the near future BAL will find an important place in the evaluation of lung cancer TME in two aspects. The first could be characteristic of immune reaction by analysis of immune cells and mediators and the second cancer molecular characteristic by free DNA and exosomes analysis.