Bronchoscopy and endobronchial ultrasound for diagnosis and staging of lung cancer
ABSTRACTVarious techniques, including standard bronchoscopy, transthoracic needle aspiration and mediastinoscopy, are used for diagnosis and staging of lung cancer. Minimizing the number of invasive procedures for lung cancer diagnosis and staging is preferred, however, and a growing number of bronchoscopic techniques are being used. Currently available techniques for the initial diagnosis of lung cancer include electromagnetic navigation bronchoscopy with computed tomography mapping and sample collection, endobronchial ultrasound (EBUS) using radial or convex probe tips, and the combination of the two approaches. EBUS with transbronchial needle aspiration (EBUS-TBNA) is highly specific and sensitive for the examination of mediastinal lymph nodes. Several studies have demonstrated the utility of this approach for less invasive lung cancer mediastinal staging. EBUS-TBNA has also been used in the collection of tissue samples for the analysis of tumor biomarkers that significantly influence the selection of cancer treatment strategies. Evidence suggests that EBUS-TBNA may be less useful for restaging patients with lung cancer after cytotoxic therapy.
EBUS RESTAGING OF LUNG CANCER
The utility of EBUS-TBNA has also been investigated for restaging of lung cancer following neoadjuvant chemotherapy. Mediastinal restaging using EBUS-TBNA was performed in 124 consecutive patients with stage IIIA-N2 NSCLC who had received chemotherapy induction.20 CT evaluation revealed partial responses for 66 patients and stable disease in 58. All patients subsequently underwent thoracotomy and attempted curative resection with lymph node dissection. Of 58 patients with stable disease on CT, 41 were EBUS-TBNA–positive for mediastinal metastasis, and all were thoracotomy-positive. However, in 17 patients who were EBUS-TBNA–negative, 14 were thoracotomy-positive and only three were thoracotomy-negative. Similarly, in 66 patients with partial response to treatment on CT, 48 were EBUS-TNA–positive and thoracotomy-positive. In 18 patients who were EBUS-TBNA–negative, 14 were thoracotomy-positive and only four were also thoracotomy-negative. Overall, the sensitivity of EBUS-TBNA was 77% in patients with partial responses and 75% in those with stable disease. The negative predictive value of EBUS-TBNA in this series was very low: 22% in the partial response group and 18% in the stable disease group.
Similar results were obtained in a European study that examined EBUS-TBNA mediastinal restaging after neoadjuvant therapy in patients with pathologically confirmed N2 disease.21 Patients with negative or uncertain EBUS-TBNA were reexamined using transcervical extended bilateral mediastinal lymphadenectomy, a surgical staging procedure that is not widely used in the United States. Of 85 mediastinal lymph nodes from 61 patients that were examined using EBUS-TBNA, nine patients (15%) had a false-negative result with EBUS-TBNA, and three patients (5%) had a false-positive result. On a per-patient basis, the sensitivity of EBUS-TBNA was 67% and the negative predictive value was 78%.
SUMMARY AND CONCLUSIONS
Newer technologies such as EBUS-TBNA make it possible to simplify the diagnosis and staging of lung cancer. Bronchoscopy with EBUS may be the preferred method for the initial diagnosis and staging of patients who have disease limited to the chest. EBUS is clearly superior to current modalities for mediastinum staging such as CT and PET, and appears to be similar to mediastinoscopy. Standard bronchoscopy with EBUS followed by mediastinoscopy, if necessary, appears to be the best strategy for initial diagnosis and staging of patients with suspected lung cancer radiographically limited to the chest. However, at this time, diagnosis and staging should rely on local expertise rather than a particular methodology. Patients with T1B lesions or higher should be considered for invasive mediastinal staging regardless of their PET or CT results. The available evidence suggests that EBUS is a reasonable initial test for mediastinal restaging following neoadjuvant chemotherapy. However, a negative EBUS in this setting should prompt additional invasive tests to confirm its findings.
