Three-dimensional analysis reveals a high incidence of lung adenocarcinoma in the upper region.

PURPOSE:The lung is a unique organ with a ventilation-perfusion mismatch, which can cause inhomogeneous incidence rates of lung cancer depending on the location in the lung. We aimed to evaluate the incidence of lung adenocarcinoma in each lobe by analyzing the incidence per unit volume, to evaluate the incidence without being affected by differences in the size of each lobe or in the size of the lungs between individuals. METHODS:The number of adenocarcinomas in each lobe was counted. Lung volumes were measured using a three-dimensional computer workstation. The tumor incidence per unit volume was analyzed based on the number of tumors in each lobe. RESULTS:The number of tumors per unit volume was 0.467 in the right upper lobe (RUL), 0.182 in the right middle lobe, 0.209 in the right lower lobe, 0.306 in the left upper segment (LUS), 0.083 in the left lingular segment, and 0.169 in the left lower lobe. The tumor incidence rate of RUL + LUS was 2.269 times that of the other lobes, a value that was significantly higher when using the bootstrap method (p < 0.001). CONCLUSIONS:The incidence of adenocarcinoma per unit volume in both upper lobes was higher than that in other lobes.