“…A study shows that pre-treatment serum CEA levels are the most important clinical predictor of tumor response after TNT. 8 A study has found that the higher the CEA level before treatment, the lower the responsiveness of TNT. 9 Some studies have found that pre-treatment CEA levels greater than 2.5 µg/L are associated with lower oCR rates (p = 0.015) and lower tumor progression rates (p = 0.006).…”