Clinical features of lung adenocarcinomas with epidermal growth factor receptor mutations and miliary disseminated carcinomatosis

Background We have occasionally encountered advanced lung cancer patients with disseminated carcinomatosis throughout the body and/or within the lung. This study investigated the clinical characteristics and outcomes of advanced lung adenocarcinoma patients with miliary disseminated carcinomatosis. Methods Patients with adenocarcinomas harboring epidermal growth factor receptor (EGFR) mutations who presented with miliary disseminated carcinomatosis (either intrapulmonary or distant site) were enrolled in the study. Clinical characteristics, treatment responses, and survival outcomes were collected from medical records. Results The most frequent EGFR mutation was an in‐frame deletion in exon 19 (n = 44, 68.8%). Arginine substitution of leucine 858 in exon 21 and alanine substitution of glycine 719 in exon 18 were detected in 19 patients (29.7%) and one patient (1.6%), respectively. Patients with miliary disseminated carcinomatosis tended to be female and non‐smokers. They expressed the E19 deletion more frequently than patients without miliary dissemination and had shorter progression‐free survival times in response to EGFR tyrosine kinase inhibitors (9.7 vs. 12.8 months, P = 0.003) and poorer overall survival (15.9 vs. 29.0 months, P = 0.077). Multivariate analyses revealed that metabolic tumor volume correlated with shorter overall survival time. Conclusions Our data indicate that lung adenocarcinoma patients with miliary dissemination have relatively shorter survival times than those without miliary dissemination. The poor prognosis of patients with miliary dissemination may reflect a high tumor burden, as represented by metabolic tumor volume.