A blood-based gene expression signature of early-stage non-small cell lung cancer.

Abstract

69 Background: Accurate blood-based biomarker for early cancer detection could be an easier and more convenient screening option than monitoring the target organ via tissue or imaging. We recently identified and validated eight genetic biomarkers of early-stage lung adenocarcinoma detectable in both peripheral whole blood (PWB) and lung tissue of smokers. Since biomarkers distinguishing benign disease versus lung malignancy across all cell types are needed in the diagnostic clinical setting, it is important to test the identified biomarkers in other lung cancer histologies, particularly in squamous cell carcinoma (SQCC), the second most common lung cancer histology after adenocarcinoma (AD). Methods: Using Real-Time Quantitative PCR (qRT-PCR), we measured mRNA levels for the eight candidate genes in PWB of 48 randomly sampled stage I SQCC cases, in addition to previously analyzed 82 AD cases and 130 age, sex, and smoking frequency matched healthy controls from the Environment And Genetics in Lung cancer Etiology (EAGLE) case-control study. The qRT-PCR data were analyzed using the 2-ΔΔCtmethod to compare SQCC cases with controls. The area under the receiver operating characteristic curve (AUC) was computed to assess the predictive accuracy of the candidate biomarkers in SQCC separately, and in SQCC and AD together. Results: Expression of TGFBR3, RUNX3, TRGC2, TRGV9, TARP, and TSTA3 genes, significantly differentiated SQCC cases versus controls, while ACP1 and VCAN gene expression did not. The eight genes combined discriminated patients with lung cancer from healthy controls with similarly high accuracy in SQCC and overall (AUC = 0.80 ± 0.1). RUNX3 showed the highest single gene accuracy for SQCC (AUC = 0.78). Conclusions: We showed that the previously identified gene expression signature of early-stage lung AD also differentiated early stage SQCC from healthy controls and demonstrated its sensitivity and specificity as a potential diagnostic lung cancer biomarker. Since lung cancer is the most common cause of cancer mortality worldwide and current smokers are at very high risk, our smoking-specific findings, if confirmed and translated into screening approaches, have the potential to impact public health.