Four genes (HOXA9, RASSF1A, SOX17, and TAC1) were identified as the best biomarkers (all p < 0.001) and incorporated into a logistic classifier: Probability of lung cancer = ex/(1 + ex), where x = 1.69 + 1.48 × log (HOXA9) − 1.25 × log (RASSF1A) + 0.27 × log (SOX17) + 0.16 × log (TAC1). The gene discussed is SOX17; the disease is lung cancer.