Correlation between computed tomographic findings, bronchioloalveolar carcinoma component, and biologic behavior of small-sized lung adenocarcinomas

Abstract

Objective Differentiation of bronchioloalveolar carcinoma from other subtypes of lung adenocarcinomas is important in the preoperative assessment of patients. We examined the biologic aggressiveness of small-sized adenocarcinomas according to the pathologically defined bronchioloalveolar carcinoma degree and its correlation with computed tomography findings. In addition, we attempted to predict which patients were suitable for a lesser resection. Methods Of 424 consecutive patients who underwent operation for primary lung cancer in the last 3 years, 114 with a histopathologically proven adenocarcinoma 3 cm or less in diameter underwent complete removal of the primary tumor. We examined the characteristics of patients classified into 3 groups based on the proportion of the bronchioloalveolar carcinoma component: 0% to 20% (n = 40), 21% to 50% (n = 38), and 51% to 100% (n = 36). We also investigated the correlation of the bronchioloalveolar carcinoma component with computed tomography findings such as ground-glass opacity (defined as a hazy increase on the lung window) and tumor shadow disappearance rate (defined as the ratio of the tumor area of the mediastinal window to that of the lung window). Results Male gender ( P = .0001), advanced pathologic stage ( P = .001), larger size of the tumor ( P = .004), nodal involvement ( P = .04), pleural invasion ( P = .0003), lymphatic invasion ( P = .002), and vascular invasion ( P = .0002) were observed more often among patients with a smaller proportion of bronchioloalveolar carcinoma. A positive and significant correlation was found between the rate of bronchioloalveolar carcinoma component and ground-glass opacity (R 2 = 0.488, P < .0001) and tumor shadow disappearance rate (R 2 = 0.727, P < .0001). As an independent predictor of nodal status, tumor shadow disappearance rate ( P = .015) and bronchioloalveolar carcinoma component ( P = .015), as well as tumor size, were significantly valuable, although ground-glass opacity proportion ( P = .086) was marginally informative. Conclusions Small-sized adenocarcinomas with a greater ratio of bronchioloalveolar carcinoma component showed less aggressive behavior. Both tumor shadow disappearance rate and ground-glass opacity ratios, which are obtained preoperatively, were well associated with bronchioloalveolar carcinoma ratios, which are determined postoperatively. Furthermore, tumor shadow disappearance rate had a stronger impact as a predictor of bronchioloalveolar carcinoma component. Preoperative assessment of tumor shadow disappearance rate may be useful to identify patients requiring a less extensive pulmonary resection.