Computed tomography-defined functional lung volume after segmentectomy versus lobectomy

Objective: Lung segmentectomy reduces the extent of resection required for lobectomy, but its resulting clinical benefits remain controversial.

Methods: Forty patients who underwent segmentectomy for stage I lung cancer over a 5-year period were matched to 40 patients who underwent lobectomy, using nearest available matching method with the estimated propensity score. We compared the functional volume of the ipsilateral lung to be resected, the ipsilateral lung to be preserved and the contralateral lung before, and 6 months after the operation, between the groups. Functional lung volume was defined as the lung volume representing normal attenuation (-600 to -910 Hounsfield units (HUs)) on computed tomography. We also compared the volumetric parameters to the spirometric parameters in 42 other patients, who underwent major lung resection for stage I lung cancer.

Results: We removed 11.6% of the functional lung volume by segmentectomy and 24.5% by lobectomy (P<0.001). However, the loss of the functional lung volume after segmentectomy was only 8.3% and that after lobectomy was 9.2%: this difference was not significant (P=0.7). Both the ipsilateral residual lung and the contralateral lung increased in functional volume more extensively after lobectomy than after segmentectomy. Increased postoperative functional lung volume was significantly correlated with improvement in postoperative pulmonary function (R=0.6, P<0.001).

Conclusion: Although lung segmentectomy can reduce the extent of lung resection, it may not contribute to preserving postoperative functional lung volume because lobectomy promotes postoperative expansion of the bilateral residual lung, which compensates postoperative pulmonary functional loss to a greater extent than segmentectomy.