Objective To investigate the relationships of the expression levels of BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) and kinesin family member 11 (KIF11) in peripheral blood with postoperative recurrence in non-muscle-invasive bladder cancer (NMIBC) patients treated with transurethral resection of bladder tumor (TURBT).

Methods A retrospective case-control study design was employed. A total of 188 NMIBC patients who received standard TURBT treatment in the 215th Hospital of Shaanxi Nuclear Industry during initial visit from January 2019 to December 2021 were selected as research objects. Patients were followed up for 36 months and divided into recurrence group (n=68) and non-recurrence group (n=120) based on pathological examination results. Additionally, 50 healthy individuals who underwent physical examinations during the same period were selected as control group. The levels of BUB1B mRNA and KIF11 mRNA in peripheral blood were compared among the recurrence group, non-recurrence group, and control group. Clinical data were compared between the recurrence and non-recurrence groups. Cox proportional hazards regression models were used to analyze the postoperative follow-up data of NMIBC patients with TURBT. Kaplan-Meier plots were drawn to assess the proportional hazards assumption (PH assumption)of the Cox model. The predictive efficacy of various indicators for postoperative recurrence in NMIBC patients was evaluated using receiver operating characteristic (ROC) curve.

Results The levels of BUB1B mRNA and KIF11 mRNA in peripheral blood in the control group, non-recurrence group, and recurrence group sucessively increased (P < 0.001). The recurrence group had a significantly higher number of patients with pathological T1 staging and multiple tumors compared to the non-recurrence group (P < 0.05). The Kaplan-Meier curves for the number of tumors, pathological staging, BUB1B mRNA, and KIF11 mRNA levels were generally parallel to recurrence rates between the two groups, meeting PH assumption. Multiple tumors, pathological T1 staging, BUB1B mRNA, and KIF11 mRNA levels were independent influencing factors for recurrence in NMIBC patients after TURBT treatment (P < 0.05). ROC curve analysis showed that the areas under the curves (AUCs) for predicting postoperative recurrence in NMIBC patients by multiple tumors, pathological T1 staging, BUB1B mRNA, and KIF11 mRNA levels were 0.674, 0.746, 0.610 and 0.642, respectively. The combined prediction using these indicators yielded an AUC of 0.826 (95%CI, 0.767 to 0.884), with a sensitivity of 86.80% and a specificity of 75.30%, indicating good predictive efficacy.

Conclusion Elevated levels of BUB1B mRNA and KIF11 mRNA in peripheral blood are significantly associated with postoperative recurrence in NMIBC patients after TURBT and serve as independent risk factors for recurrence. As non-invasive biomarkers, BUB1B mRNA and KIF11 mRNA in peripheral blood combined with clinical parameters can significantly improve the predictive efficacy of postoperative recurrence, providing a new strategy for individualized monitoring.