Prognostic value of the IASLC/ATS/ERS classification and IMP3 expression in lung adenocarcinoma of Chinese cases

The IASLC/ATS/ERS classification system was proposed in 2011 to improve the histological subtypes of lung adenocarcinoma, while the prognostic value of the combination of histological predominant subtypes is not consistent. IMP3 is an oncofetal protein which has been proved associated with aggressive tumor behavior in malignancies, but few reports were investigated in lung adenocarcinoma. The aim of this study is to explore the prognostic value of the IASLC/ATS/ERS classification and IMP3 expression in lung adenocarcinoma of Chinese cases. A total of 196 cases were classified according to the IASLC/ATS/ERS classification system and immunohistochemically analyzed by using a monoclonal antibody against IMP3. Univariate survival analysis indicated patients with solid-predominant subtype had shorter disease-free survival (P = 0.003) and overall survival (P = 0.014) compared to those with non-solid predominant subtype. Multivariate survival analysis revealed that solid-predominant subtype could be an independent prognostic factor for disease-free survival (HR: 1.22, 95% CI: 1.05-1.41; P = 0.008). Analysis of IMP3 expression showed that IMP3 was more frequently overexpressed in tumors with advanced pTNM stage (P < 0.001), larger tumor size (P = 0.036), poorer histological differentiation (P < 0.001), lymph node metastasis (P < 0.001), and solid-predominant subtype (P < 0.001). Survival analysis also confirmed that patients in IMP3 high-expression group had both worse disease-free survival (P = 0.039) and overall survival (P = 0.029) than those in IMP3 low-expression group. Our results illustrated that solid-predominant subtype according to the IASLC/ATS/ERS classification is an independent prognostic factor, and IMP3 overexpression is associated with aggressive tumor behavior and poor clinical outcome in lung adenocarcinoma.