Transcriptomic Profile of Lymphovascular Invasion, a Known Risk Factor of Pancreatic Ductal Adenocarcinoma Metastasis

Lymphovascular invasion (LVI) is an aggressive pathologic feature and considered a risk factor for distant metastasis. We hypothesized that pancreatic ductal adenocarcinomas (PDACs) with LVI are associated with shorter survival, as well as aggressive cancer biology and lymphangiogenesis in transcriptomic analysis. Utilizing the cancer genome atlas (TCGA)-PDAC cohort, we found that positive LVI was significantly associated with positive perineural invasion (PNI) (p= 0.023), and higher American Joint Committee on Cancer (AJCC) T (p= 0.017) and N (p< 0.001) categories. Furthermore, positive LVI was associated with shorter overall survival (OS) (p= 0.014) and was an independent risk factor of poor OS. Although there was no association between LVI status and lymphangiogenesis, epithelial-mesenchymal transition (EMT), or metastasis-related genes, Gene Set Enrichment Analysis revealed a strong association with cell-proliferation-related gene sets such as mitotic spindles (Normalized enrichment score (NES) = 1.76,p= 0.016) and G2/M checkpoints (NES = 1.75,p= 0.036), as well as with transforming growth factor beta (TGF-beta) signaling (NES = 1.61,p= 0.043), which is a known mechanism of metastasis in PDACs. In conclusion, positive LVI was an independent risk factor of poor OS in PDACs. We found that PDACs with LVI were possibly associated with accelerated cell proliferation and enhanced TGF-beta signaling independent of lymphangiogenesis. Transcriptomic profiling elucidates more precise tumor biology of LVI-positive PDACs.