Poor prognosis of stage I lung adenocarcinoma patients determined by elevated expression over pre/minimally invasive status of COL11A1 and THBS2 in the focal adhesion pathway

Around 20% of stage I lung adenocarcinoma (LUAD) patients die within five years after surgery, and efforts for developing gene-expression based models for risk-tailored post-surgery treatment are largely unsatisfactory due to overfitting-related lack of validation and extrapolation. Because patients with adenocarcinomas in situ (AIS) and minimally invasive (MIA) LUAD are completely curable by surgical resection, we hypothesize that poor-prognosis stage I patients may exhibit key molecular characteristics deviating from AIS/MIA. We first found focal adhesion (FA) as the only pathway significantly perturbed at both genomic and transcriptomic levels by comparing 98 AIS/MIA and 99 invasive LUAD patients. Then, we identified two FA pathway genes (COL11A1 and THBS2) strongly upregulated from AIS/MIA to stage I while expressed steadily from normal to AIS/MIA. Furthermore, unsupervised clustering separated stage I patients into two molecularly and prognostically distinct subtypes (S1 and S2) based solely on the expression levels of COL11A1 and THBS2 (FA2). Subtype S1 looked like AIS/MIA, whereas S2 exhibited more somatic alterations, elevated expression of COL11A1 and THBS2, and more activated cancer-associated fibroblast (CAF). The prognostic performance of the knowledge-driven and overfitting-resistant FA2 model was validated with 12 external data sets and may help reliably identify high-risk stage I patients for more intensive post-surgery treatment.