The tumor markers were also elevated in PC groups, but the MLR model of salivary metabolites showed the highest number of positive subjects (83.3%) for PC with Stage III, while tumor markers showed lower sensitivities: 0.00%, 50.0%, 66.7%, and 50.0% for CEA, CA19-9, DUPAN2, and SPAN1, respectively. The gene discussed is CEACAM5; the disease is pachyonychia congenita.