When applied to Logistic analysis, post-CRT distance from the anal verge (OR =0.840, 95% CI: 0.723-0.975, P = 0.022), post-CRT tumor size (OR = 0.565, 95% CI: 0.386-0.827, P = 0.003), post-CRT circumferential extent of tumor (OR = 0.021, 95% CI: 0.004-0.114, P < 0.001), pre-CRT CEA level (OR = 2.004, 95% CI: 1.058-3.798, P = 0.033), and post-CRT CEA level (OR = 3.767, 95% CI: 1.080-13.148, P = 0.038) were found to be independently associated with pCR following nCRT (Table 3). Here, CEACAM5 is linked to neoplasm.