PDCD1 and neoplasm: Univariate analysis identified several clinical and pathological factors significantly associated with TRG (1a+1b) response, including age (P < 0.05), pretreatment lymph node positivity (P < 0.05), PD-1 inhibitor administration (P < 0.05), tumor differentiation grade (P < 0.05), and lymph node metastasis (P < 0.05).