CEACAM5 and rectal neoplasm: In comparison with the patients without postoperative relapse, rectal neoplasms (P = 0.018), perineural invasion (P = 0.016), elevated preoperative serum CEA levels (P = 0.001), elevated postoperative serum CEA levels (P < 0.001), and positive biochip results (P < 0.001) were more frequently noted in the patients with relapse (Table 4).