The pathways of cell cycle, mismatch repair, pathways in cancer, small cell lung cancer, ubiquitin mediated proteolysis and WNT signaling pathway were significantly enriched in high-risk group, whereas pathways of arachidonic acid metabolism, drug metabolism, PPAR signaling pathway, fatty acid metabolism, xenobiotics metabolism and tryptophan metabolism significantly enriched in low-risk group. The gene discussed is PPARA; the disease is small cell lung carcinoma.