Letter to the Editor: Bacillus Calmette-Guerin (BCG) Treatment Failures with Non-Muscle Invasive Bladder Cancer: A Data-Driven Definition for BCG Unresponsive Disease

Bladder tumour resection weight as a prognostic factor for recurrence and progression in patients with high-risk non-muscle invasive bladder treated with BCG

INTRODUCTION

Predicting outcomes of patients with high-risk non-muscle invasive bladder cancer (HR-NMIBC) is critical. Here, we evaluate whether bladder tumor resection weight might serve as a prognostic factor for recurrence and progression of HR-NMIBC patients treated with Bacillus Calmette-Guérin (BCG).

METHODS

In this retrospective, single-centre study in the UK, we analysed a consecutive cohort of HR-NMIBC patients who have received adequate intravesical BCG immunotherapy between 2009 and 2019. Univariable and multivariable Cox proportional hazards models were used to assess the association of resection weight and established predictors with recurrence and progression.

RESULTS

A total of 187 HR-NMIBC patients were analysed. The median resection weight was 1.4g (range: 0.2-28.5g). Within a median follow-up of 41 months, 58 (31%) tumors recurred and 19 (10%) progressed. Fifty-four patients (29%) died from any cause and 16 (9%) died from bladder cancer. Both the risk of recurrence (P = .007) and progression (P = .019) increased with rising resection weight. On the multivariable analysis, a resection weight of ≥ 2g and ≥ 3g conferred a 4.35-fold and a 9.03-fold increased risk of bladder cancer recurrence (P < .001) and progression (P < .001), respectively. The addition of resection weight improved the C index of multivariable standard prognostic models to a clinically significant extent (+ 3.8% for recurrence, + 4.3% for progression).

CONCLUSION

In our HR-NMIBC patient cohort treated with BCG, bladder tumor resection weight was associated with disease recurrence and progression. Its addition improves discrimination of standard prognostic factors. Measurement may therefore be considered for routine clinical practice.

Prognostic Implication of the United States Food and Drug Administration-defined BCG-unresponsive Disease

The category "BCG-unresponsive disease", formulated by experts at the request of the United States Food and Drug Administration, denotes a group of patients with recurrent non-muscle-invasive bladder cancer for whom continued BCG treatment is unlikely to provide benefit. Although quickly adopted for trial design, many of the nuances within the definition lack validation. In this study, we evaluated the prognostic value of BCG unresponsive designation (i.e. recurrence after induction plus at least 1 maintenance course of BCG) by comparing the oncologic outcomes of these patients with those recurring after induction BCG alone. We confirm that appropriately defined, BCG-unresponsive patients are more likely to require salvage radical cystectomy (54.5% vs 17.9%, p=0.002). Moreover, those opting for second-line bladder-sparing therapies are less likely to remain free of tumor recurrence (23% vs 69.2%, p=0.003). On multivariate analysis, BCG-unresponsive disease independently predicts inferior high-grade recurrence-free survival (hazard ratio [HR]: 6.25, 95% confidence interval [CI]: 2.27-16.67; p<0.001) and cystectomy-free survival (HR: 3.85, 95% CI: 1.49-10.0; p=0.006). Our data confirm the prognostic implication of the BCG unresponsive definition i.e. recurrence of high grade disease after induction and one course of maintenance BCG, and support its use in counseling and risk stratification of patients with tumor recurrence after BCG. Patient summary: Patients who have BCG-unresponsive disease, that is, high-grade non-muscle-invasive bladder cancer recurring after BCG induction and maintenance, have a low likelihood to respond to further BCG treatment and should consider radical cystectomy or clinical trial enrollment.