Given the great benefit of NACRT response predictors for clinical practice and for rectal cancer patients, this question has become widely studied, and several authors have reported many molecular biomarkers for prediction of pathological response or tumor downstaging, such as CD44 and proliferating cell nuclear antigen mRNA levels [36]; the gene signature composed of LRRIQ3, FRMD3, SAMD5, and TMC7 [37]; GHRH-R and Hsp90 proteins [38]; Topo I [39]; and beclin 1 [40], survivin [41], among others. Here, PCNA is linked to rectal cancer.