Measurement of tumour markers in bronchoalveolar lavage fluid

Routine fibreoptic bronchoscopy is very effective for diagnosing central lung cancer, but the diagnostic yield is lower for peripheral tumours. Complementary methods such as bronchoalveolar lavage (BAL) are being investigated in the hope of improving the diagnostic yield for such cases. This report reviews current findings using this approach and gives recommendations for a better standardization of procedures to facilitate comparisons. The presence of malignant cells in bronchial washings or BAL fluid has been shown to be one of the earliest signs of disease progression in patients with lung cancer. Various tumour markers have also been detected in BAL fluid, and their clinical utility is under investigation. These include carcinoembryonic antigen (CAE), neuron-specific enolase (NSE), calcitonin and α₂-foetoprotein. None of these are completely tumour-specific, and for this reason groups of markers are advised. Measurement of CAE in BAL fluid has been of use as an adjunctive test in the diagnosis of peripheral lung cancer, but currently it is of little value by itself owing to its low sensitivity. The specificity of this marker was 90% and improvements in BAL standardization may enable its true sensitivity to be determined. Pretreatment measurements of NSE in serum have been reported to be of prognostic value in patients with small cell lung cancer. Elevated levels of NSE have been demonstrated in the BAL fluid of patients with lung tumours, but the clinical utility of this and other tumour markers detected in BAL fluid is not known. There is no consensus on how measurements of tumour markers in bronchoalveolar lavage fluid should be used nor their diagnostic or prognostic utility, but most investigators agree that bronchoalveolar lavage fluid is an ideal fluid to study tumour markers. Work should continue to improve standardization and sensitivity, as any technique which could aid in the successful management of lung cancer would have a major clinical role.