Three-dimensional computed tomography volumetry and pulmonary function outcomes after segmentectomy versus lobectomy.

OBJECTIVES

Recent randomized trials have demonstrated that sublobar resection, including segmentectomy, provides noninferior overall survival compared with lobectomy in early-stage non-small cell lung cancer. However, these trials have shown unexpectedly small differences in postoperative pulmonary function. Compensatory expansion of the residual lung may explain these limited differences. Therefore, we used 3-dimensional computed tomography volumetry to quantify compensatory expansion of the residual lung and clarify its role in functional preservation after segmentectomy compared with lobectomy.

METHODS

In this prospective observational study we analyzed 51 patients who underwent segmentectomy and 64 patients who underwent lobectomy. Three-dimensional computed tomography volumetry was performed preoperatively and at 12 months postoperatively to quantify nonemphysematous lung volume (NELV; morphologically preserved parenchyma) and low-attenuation volume (emphysematous regions). Changes in lung volume and pulmonary function were expressed as percentages of preoperative values. Volumetric and functional outcomes were compared overall and by resected lobe.

RESULTS

NELV was positively correlated with forced expiratory volume in 1 second (FEV1). Planned resection NELV was significantly smaller in segmentectomy than in lobectomy (8.5% vs 19.2%, P < .001). Despite this difference, postoperative NELV (94.8% vs 93.5%, P = .545) and FEV1 (93.7% vs 92.7%, P = .483) were similar. Compensatory expansion occurred predominantly through NELV rather than low-attenuation volume. After segmentectomy, despite removal of 35.9% of the lobe volume, the operated lobe retained only 55.6%, indicating underexpansion. Right upper lobe segmentectomy was associated with better preserved FEV1 than lobectomy (98.7% vs 91.5%, P = .015), despite similar volumetric preservation.

CONCLUSIONS

Both procedures achieve similar outcomes through compensatory expansion, which explains the unexpectedly small functional differences observed in recent randomized trials.