The Impact of Partial versus Complete BCG Intravescial Therapy on Bladder Cancer Outcomes in High-risk Non-muscle Invasive Bladder Cancer (NMIBC): Implications for Global BCG Shortages
Michael E. Rezaee, MD, MPH1, A. Aziz Ould Ismail, MD, MS2, Chiamaka L. Okorie, BSc3, Kristine E. Lynch, PhD4, Florian R. Schroeck, MD, MS5.
1Dartmouth-Hitchcock Medical Center, Lebanon, NH, 2VA Medical Center, White River Junction, VT, 3Geisel School of Medicine at Dartmouth, Lebanon, NH, 4VA Salt Lake City Health Care System and University of Utah, Salt Lake City, UT, 5White River Junction VA Medical Center, White River Junction, VT.
BACKGROUND: Adjuvant intravesical Bacillus Calmette-Guérin (BCG) is used to reduce disease recurrence and progression in patients with high-risk non-muscle invasive bladder cancer (NMIBC). Unfortunately, repetitive global shortages of BCG have disrupted guideline-recommended intravesical therapy practices for many high-risk patients. BCG instillations have been rationed (i.e., partial induction), so at least those at highest risk for disease recurrence and progression can undergo BCG treatment. The impact of delivering fewer BCG instillations than currently recommended has not been thoroughly evaluated. The purpose of this study was to assess the association of partial vs. complete BCG induction with bladder cancer outcomes in patients with high-risk NMIBC.
METHODS: This is a retrospective cohort study of Veterans who were diagnosed with high-risk NMIBC (high grade (HG) Ta, T1, or Carcinoma in Situ) between 2005 and 2011 who received at least one dose of adjuvant BCG during a 6 month intravesical therapy window after diagnosis. Patients were categorized into partial BCG induction (< 5 BCG instillations) versus complete BCG induction (>= 5 BCG instillations) groups. Propensity score adjusted regression models were used to assess the association of partial BCG induction with risk of disease recurrence and bladder cancer death, stratified by Ta vs. T1 disease. Associations with progression to invasive disease (T1/T2) or bladder cancer death were evaluated among those diagnosed with HG Ta disease.
RESULTS: Among 540 patients with high-risk NMIBC, 114 (21.1%) received partial BCG induction, while 426 (78.9%) received complete BCG induction. This reflected a mean of 2.8 (SD 1.2) versus 6.0 (SD 0.8) induction doses per patient, respectively. Baseline patient characteristics did not differ significantly between groups. Partial vs. complete BCG induction was not significantly associated with increased risk of disease recurrence for patients with HG Ta (cumulative incidence ([CIn] 46.6% vs. 53.9% at 5 years, p=0.38) or T1 (CIn 47.1% vs. 56.7 at 5 years, p=0.19) disease. Similarly, partial vs. complete BCG induction was not significantly associated with increased risk of bladder cancer death for patients diagnosed with HG Ta (CIn 4.7%7vs. 5.4% at 5 years, p=0.87) or T1 (CIn 10.0% vs. 11.4% at 5 years, p=0.77) disease. Among patients diagnosed with Ta disease, partial vs. complete BCG was not significantly associated with risk of progression to invasive disease (T1/T2) or bladder cancer death (CIn 13.1% vs. 19.0% at 5 years, p=0.37; Figure Panel 1).
CONCLUSIONS: Patients with high-risk NMIBC who underwent partial BCG induction experienced similar bladder cancer outcomes compared to those who received complete BCG induction. These findings suggest that a reduced number of adjuvant BCG instillations in the induction period may be an alternative treatment strategy for some high-risk patients, particularly during global shortages of BCG.
Figure Panel 1: Cumulative incidence plots showing the probability of disease recurrence, bladder cancer death, and progression to invasive disease (T1/T2) by BCG induction status. 
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