The mean values in ng/mL of baseline and peak carcinoembryonic antigen (CEA) in the periodontitis patient group, mean ± SD (0.44 ± 0.39, 0.69 ± 0.49), were much higher compared to the non-periodontitis group (0.11 ± 0.29, 0.35 ± 0.45), 95% CI: 0.12–0.54, p < 0.001 and 95% CI: 0.06–0.62, p = 0.005, respectively. Here, CEACAM5 is linked to periodontitis.