Non–Small-cell Lung Cancer Patients With Adenocarcinoma Morphology Have a Better Outcome Compared With Patients Diagnosed With Non–Small-cell Lung Cancer Favor Adenocarcinoma

Non–small-cell lung cancer patients are treated differently, depending largely on histology identification of squamous versus adenocarcinoma subtypes. This distinction has been classically on the basis of micromorphology features, but immunohistochemistry (IHC) has become a major tool for this distinction in recent years. We retrospectively compared the outcome of adenocarcinoma patients considering their diagnosis being on the basis of morphology versus IHC. We found the method of diagnosis to be an independent prognostic factor. We believe that identification of adenocarcinoma on the basis of morphology versus IHC should be integrated into the evaluation of such patients and should be considered as a stratification factor in clinical trials. Background Non–small-cell lung cancer (NSCLC) includes 2 major histologic subtypes: squamous cell carcinoma and non-squamous carcinoma, mainly adenocarcinoma, a distinction that carries significant clinical and therapeutic implications. NSCLC is diagnosed as adenocarcinoma or as squamous cell carcinoma on the basis of histologic parameters. However, when morphology is inconclusive, tumors with immunohistochemistry (IHC) findings characteristic of adenocarcinoma are referred to as “NSCLC favor adenocarcinoma” (NFA). Our aim was to evaluate whether pulmonary adenocarcinoma diagnosis on the basis of morphology had a similar prognosis compared with NFA. Patients and Methods Patients with advanced NSCLC non-squamous carcinoma who were treated with a platinum-pemetrexed doublet as first-line combination chemotherapy were identified. Demographic, clinical, laboratory, and pathological data including the method of pathological diagnosis (morphology or IHC) was extracted from the clinical charts. The correlation between the various parameters and overall survival was evaluated. Results Lack of adenocarcinoma morphology, male sex, smoking history, and negative thyroid transcription factor 1 IHC were associated with worse prognosis and shorter overall survival in multivariate analysis. High white blood cell count, absolute neutrophil count, neutrophil to lymphocyte ratio, and low albumin levels were associated with shorter overall survival only in univariate analysis. Conclusion Pulmonary adenocarcinoma has a better prognosis than NFA, regarding advanced NSCLC treated with platinum-pemetrexed combination chemotherapy. This distinction should be a stratification factor in clinical trials and a prognostic factor to consider in analysis of previous trials.