The results from our univariate analysis indicated that the tumor length was ≤4 cm (P = 0.015), circumferential extent ≤50% (P = 0.022), normalization of post-treatment CEA level <  5 ng/mL (P = 0.037), and CEA exponential decrease (P = 0.028) were associated with good TRG (0–1) (Table 2). This evidence concerns the gene CEACAM5 and neoplasm.