BACKGROUND: According to guidelines, it is possible to biopsy lung tumors "immediately adjacent to the esophagus" with EUS-B-FNA. However, it is unknown what "immediately adjacent" exactly means.
OBJECTIVE: to investigate the possibility of achieving EUS-B-FNA biopsies from a lung tumor depending on the distance from the esophagus and to establish the maximal allowable distance between the tumor and the esophagus.
METHODS: In a prospective observational study, we included patients with a lung tumor located maximum 6 cm from the esophagus and indication of EUS-B-FNA from the tumor. The tumors were of different sizes. In a plot presenting the tumor size-distance relationship in cases with (biopsy) versus without (non-biopsy) successful EUS-B-FNA, a separation line representing the threshold between the groups were identified and a biopsy-index equation established. The maximal tumor-size corrected distance (TSCD) was calculated using the residuals to the separation line.
RESULTS: In total, 70 patients were included. EUS-B-FNA from the lung tumor was possible in 46 patients. All tumors with a distance from the esophagus below 19 mm could be biopsied. The maximal allowable esophagus-tumor distance depended on tumor size. From the separation line, a biopsy-index equation was established with the sensitivity of 93.5%, a specificity of 100%, and total accuracy of 95.7%. The TSCD was 31 mm (sensitivity: 95.7%, specificity 75.0%, and accuracy: 88.6%).
CONCLUSION: We established a biopsy-index equation to predict the achievability of a lung tumor using EUS-B-FNA depending on distance to esophagus and tumor size. A general maximal TSCD was 31 mm.