Noninvasive Bronchoscopic Specimens in the Diagnosis of Lung Cancer

Abstract

One of the most useful applications of flexible bronchoscopy has been in the diagnosis of lung cancer. The diagnostic yield of peripheral lesions, however, is much lower than endobronchially visible lesions, despite the use of multiple sampling techniques. We review the experience with noninvasive bronchoscopic specimens—bronchial aspirates, washings, and bronchoalveolar lavage (BAL)—in the diagnosis of peripheral lung cancers. In addition, the use of BAL tumor markers in the diagnosis of lung cancers is also reviewed. The overall diagnostic yield of noninvasive bronchoscopic specimens is just less than 50% for peripheral lung cancers. Limited study numbers have not shown a significant increase in diagnostic yield when added to more invasive biopsy specimens and brushings. However, the general consensus from studies suggests that BAL should be included in the evaluation of peripheral lesions, and that the diagnostic yield is likely to improve when combined with biopsy and brushing. BAL appears to have its highest yield in infiltrative malignancies, such as bronchoalveolar carcinoma and lymphangitic carcinomatosis. A limitation of BAL is the consistent finding that the cytologic diagnosis of malignancy does not always correspond to the histologic pattern. The average correlation rate was 80%; however, most discrepancies occurred among the subtypes of nonsmall cell lung cancers. Tumor markers, despite extensive research efforts, remain primarily a research tool. Sufficient data do not exist to justify their use in routine clinical practice.