Insulin-like growth factor 1 receptor expression in advanced non-small-cell lung cancer and its impact on overall survival
Background. The insulin-like growth factor 1 receptor (IGF1R) expression has been addressed as a potential prognostic marker in non-small-cell lung cancer (NSCLC) in various studies; however, the associations between IGF1R expression and prognosis of advanced NSCLC patients is still controversial. The aim of our observational, cohort study was to evaluate the expression of IGF1R in advanced NSCLC and its prognostic role. A subgroup analysis was performed to address the influence of pre-existing type 2 diabetes mellitus (T2DM status) on IGF1R expression and overall survival (OS).
Patients and methods. IGF1R expression was evaluated in 167 consecutive advanced NSCLC patients, diagnosed and treated at one university institution, between 2005 and 2010. All patients received at least one line of standard cytotoxic therapy. IGF1R expression was determined by IHC, with score ≥1+ considered as positive. Information on baseline characteristics, as well as patients follow-up data, were obtained from the hospital registry. Associations of IGF1R expression with clinical characteristics were compared by χ2 test. OS was evaluated using Kaplan–Meier method and log-rank test was used to determine differences between subgroups. Univariate and multivariate analyses were performed using Cox proportional hazards regression model.
Results. IGF1R expression was positive in 79.6% of patients, significantly more often in SCC compared to NSCC histology (88.7% vs. 74.3%; P = 0.03). IGF1R positivity did not correlate with T2DM status or with other clinical features (sex, smoking status, performance status). Median OS was similar between IGF1R positive and IGF1R negative group (10.2 versus 8.5 months, P = 0.168) and between patients with or without T2DM (8.7 versus 9.8 months, P = 0.575). Neither IGF1R expression nor T2DM were significant predictors of OS in the Cox analysis.
Conclusions. IGF1R or T2DM status were not significantly prognostic in our collective of advanced NSCLC treated with at least one line of chemotherapy. In addition, no association between T2DM status and IGF1R expression was found. Further studies on IGF1R expression and its prognostic as well as therapeutic consequences in a larger collective of advanced NSCLC patints , with or without T2DM, are needed.