POU5F1 and neoplasm: Significant associations were found in cases with elevated ΔCEA values and negative ΔOCT4 (indicative of progression and poor therapeutic response), including undifferentiated tumor phenotype (PR 1.69; 95% CI: 1.06 - 2.70, p=0.012), advanced tumor progression stage (PR 2.12; 95% CI: 1.22 - 3.70, p=0.002), and initial positive expression of OCT4 (PR 7.88; 95% CI: 2.08 - 30.1, p <0.001).