BUB1 and neoplasm: After incorporating tumor stage and grade with BUB1 expression in the E-MTAT-4321 cohort, NMIBC patients in the BUB1 high-grade and T1 stage group showed the worst PFS, whereas those in the BUB1 low-grade and Ta stage group had the best PFS (log-rank test, p < 0.0001; Figure 3D).