Tumour–pleura relationship on CT is a risk factor for occult lymph node metastasis in peripheral clinical stage IA solid adenocarcinoma

Objectives To investigate whether the tumour–pleura relationship on computed tomography (CT) is a risk factor for occult lymph node metastasis (OLNM) in peripheral clinical stage IA solid adenocarcinoma. Methods A total of 232 patients were included in the study. The tumour–pleura relationship was divided into four types: type 1, the tumour was unrelated to the pleura; type 2, the tumour was not in contact with the pleura, and one or more linear or striated pleural tags were visible; type 3, the tumour was not in contact with the pleura, and one or more linear or striated pleural tags with soft tissue component at the pleural end were visible; and type 4, the tumour was in contact with the pleura. Univariate and multivariate logistic regression analyses were used to identify the predictive factors, including the tumour–pleura relationship, clinical factors, conventional CT findings, and pathology-reported visceral pleural invasion, for OLNM. Results Type 3 and 4 tumour–pleura relationships were more likely to have visceral pleural invasion than type 1 and 2 tumour–pleura relationships ( p < 0.001). Univariate and multivariate logistic regression analyses revealed that the type 3 or 4 tumour–pleura relationship (OR: 3.261, p = 0.026), carcinoembryonic antigen level (OR: 3.361, p = 0.006), cytokeratin 19 fragments level (OR: 2.539, p = 0.025), and mediastinal window tumour size (OR: 1.078, p = 0.020) were predictive factors for OLNM. Conclusions The type 3 or 4 tumour–pleura relationship is correlated with a greater risk of OLNM in peripheral clinical stage IA solid adenocarcinoma. Key Points • The tumour–pleura relationship on CT is a risk factor for occult lymph node metastasis in peripheral clinical stage IA solid adenocarcinoma. • Other risk factors for OLNM include CEA level, CYFRA level, and mediastinal window tumour size. • Pathology-reported visceral pleural invasion is not a risk factor for OLNM.