Background: Accurate prediction of pathologic response to chemoradiation (CHEMO-XRT) has a significant impact on the treatment of patients with non-small cell lung cancer (NSCLC) and mediastinal lymph node (LN) metastasis (N2 disease).
Objective: This pilot study evaluates the ability of EUS-FNA to predict pathologic response in LN following CHEMO-XRT in NSCLC patients with N2 disease.
Patients and methods: Retrospective analysis of prospectively collected data on patients with NSCLC and biopsy-proven N2 disease who underwent restaging by EUS following CHEMO-XRT. At restaging, FNA was performed on the same LN, if present, or any other visible LN in the posterior mediastinum. Response to therapy (N0 disease) was defined by either absence of mediastinal LN or residual disease on FNA. Those staged N0 by EUS underwent tumor resection with complete LN dissection.
Results: Fourteen patients met the criteria for evaluation. Restaging by EUS suggested disease response in 7 patients and residual disease in 6; tissue yield was unsatisfactory in 1 patient. Eleven of 14 patients in whom mediastinal LN were seen at restaging by EUS underwent FNA: the aspirate was benign in 4, residual disease was found in 6, and an inadequate sample was obtained in 1 patient. In 3 patients no mediastinal LN were evident at EUS. Final diagnosis on the 7 patients in whom EUS suggested N0 disease was established at surgery: EUS was true negative in 6 and false negative in 1. Of the 6 patients with residual disease, 5 underwent palliative CHEMO-XRT and 1 underwent extended tumor resection. The patient in whom tissue sampling was inadequate was found to have residual disease at surgery. The diagnostic accuracy of EUS-FNA for predicting mediastinal response to preoperative CHEMO-XRT was 86%.
Conclusions: EUS-FNA appears to qualify as an accurate, safe and minimally invasive diagnostic technique for restaging of mediastinal LN after CHEMO-XRT in NSCLC patients. Given this promising preliminary data, a prospective evaluation is justified.