Impact of bilateral mediastinal lymph node dissection on pulmonary function during the early postoperative period after curative-intent lung surgery for cancer: a randomized study.

Background: Bilateral lymph node dissection is not a standard surgical treatment for non-small cell lung carcinoma. However, data from anatomical studies showing lymph flow to the contralateral mediastinal lymph nodes have prompted attempts to extend lymph node dissection to the contralateral mediastinum. Little is known about the functional effects of extended lymphadenectomy. This study aimed to determine whether bilateral mediastinal lymphadenectomy (BML) performed as part of lung cancer surgery leads to more severe impairment of respiratory function than standard systematic lymph node dissection (SLND).

Methods: Respiratory function data were derived from a randomized clinical study (BML-1), which included patients with non-small cell lung cancer (NSCLC) who underwent curative-intent lung resection with standard SLND or BML. Lung function tests were performed preoperatively and on postoperative days 1, 3-5, 7-9, and 30-32.

Results: Data from 89 patients were available for the final analysis of the BML-1 study: 40 and 49 underwent BML and SLND, respectively. Complete respiratory function test data were available for 35 patients. The age, sex, Thoracoscore, revised cardiac risk index, dyspnea score, lobar location of the tumor, histology, preoperative pulmonary function test results, and type of lung resection were comparable for both groups. The vital capacities (VCs) were not different on postoperative days 1, 3-5, 7-9, and 30-32 (P=0.49, 0.66, 0.18, and 0.16, respectively). The forced expiratory volumes in 1 second (FEV) obtained at the same time points were not different (P=0.40, 0.72, 0.81, and 0.32, respectively).

Conclusions: BML was not associated with a more severe deterioration of respiratory function than standard (unilateral) lymph node dissection.