Multivariate analysis of the prognostic significance of resection weight after transurethral resection of bladder tumor for non-muscle-invasive bladder cancer

Abstract

Purpose: Tumor size and multiplicity are known to be important prognostic factors in non-muscle-invasive bladder cancer (NMIBC). However, evaluation of accurate tumor size is subjective and difficult. Furthermore, there are limitations to the objectification of tumor volume in the case of multiple lesions. In this study, we investigated the relation between resection weight after transurethral resection of bladder tumor (TURBT) and the prognosis of NMIBC.

Materials and methods: This was a retrospective analysis of 406 patients diagnosed with pTa or pT1 bladder tumors after TURBT between September 1999 and May 2010. The patient's age, sex, underlying diseases, cancer stage, grade, multiplicity, tumor size, lymphovascular invasion, and resection weight were analyzed in relation to cancer progression and recurrence. The resection weight was weighted after formaldehyde fixation.

Results: The mean follow-up time was 76.9 months (range, 12 to 167 months) in 406 patients diagnosed as having NMIBC. Mean resection weight was 4.5 g (range, 0.1 to 35.0 g). The cancer recurred in 99 patients (24.4%), and disease progression was noted in 30 patients (7.4%). Resection weight was categorized as greater than or less than 2 g by use of receiver operator characteristic curves. Cancer grade (p=0.022) and multiplicity (p=0.043) were significantly related to cancer recurrence in the analysis with Cox's multivariate proportional hazard model. Cancer grade (p=0.001) and resection weight (p=0.018) were related to disease progression.

Conclusions: Resection weight after TURBT was significantly related to progression of NMIBC. Resection weight was an independent factor of progression. Further management should be considered if the resection weight exceeds 2 g.

Keywords: Prognosis; Tumor burden; Urinary bladder neoplasms.

FIG. 1

Receiver-operating characteristic (ROC) curve (tumor weight). Points (black arrow) on the ROC curve represent the possibility levels generated from the logistic regression analysis that was used to select the optimal cutoff point. A predicted probability of 2 provided a sensitivity of 70.5% and a specificity of 57.0%.

FIG. 2

Kaplan-Meier plot for recurrence comparing Ta and T1 tumors (p=0.001), grades low and high (p=0.125), tumors greater than and less than 3 cm (p=0.190), multiplicity more than 3 and less than 3 (p=0.024), tumors greater than and less than 2 g (p=0.184), and lymphovascular invasion (p=0.002).

FIG. 3

Kaplan-Meier plot for progression comparing Ta and T1 tumors (p=0.013), grades low and high (p=0.002), tumors greater than and less than 3 cm (p=0.166), multiplicity more than 3 and less than 3 (p=0.001), tumors greater than and less than 2 g (p=0.017), and lymphovascular invasion (p=0.023).