The role of endobronchial ultrasound in central early lung cancer.

Central early lung cancers (CELC) are tumors arising from the central airways, roentgenographically occult, which are usually diagnosed by bronchoscopy after a positive sputum cytology. Most CELCs are undetectable for conventional white light bronchoscopy (WLB) but can be identified under autofluorescence bronchoscopy (AFB). Although AFB increases the sensitivity of WLB in detecting CELC, its low specificity remains a problem. Surgery has been the most accepted treatment for CELCs; however 20-30% of patients suffering CELC tend to have multicentricities and usually present with poor cardiopulmonary status. Therefore, surgery is not suitable in most of the cases and other therapeutic options such as bronchoscopic treatments should be considered. Because most endoscopic treatments are unlikely to be curative if the tumor has spread beyond the bronchial cartilage, accurate evaluation of CELC bronchial wall invasion is critical before selecting a bronchoscopic treatment. Endobronchial ultrasound (EBUS) is a relatively new technique that has proven to be useful in the evaluation of the normal and cancer-invaded bronchial wall. Some authors have demonstrated that after adding EBUS assessment to AFB in autofluorescence-positive lesions the specificity increases from 50 to 90%. Other studies have focused on the ability of EBUS to detect bronchial wall invasion in patients with CELCs. They compared the EBUS images with pathological findings of surgical specimens of patients that underwent surgery; in most of the cases the correlation between EBUS and pathological findings increased over 90%. Furthermore, in patients not eligible for surgery, EBUS has proven to predict patients expected response to endoscopic treatments.