APOL6 and rectal cancer: In order to further identify the core genes affecting the prognosis of rectal cancer among the key genes, we performed random survival forest analysis of these 1,153 genes, and we identified genes with relative importance > 0.3 as final markers, and finally screened five key genes, TOP2A, MATR3, HOXC6, APOL6, and JOSD1 (Fig. 3).