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SWOG 8507
After induction BCG for high-risk NMIBC, does a maintenance BCG programme reduce recurrence compared with observation?
Population384 high-risk patients with recurrent Ta/T1 disease or carcinoma in situ who had responded to induction BCG.InterventionMaintenance BCG: three weekly instillations at 3 and 6 months, then every 6 months through 3 years.ComparatorNo maintenance BCG after induction.Key endpointRecurrence-free survival.Absolute Effect
5-year recurrence-free survival60% vs 41% (+19 points)
Maintenance BCG produced a large absolute improvement in recurrence-free survival.
Treatment completionOnly 16% completed all scheduled maintenance courses
The efficacy result therefore has to be interpreted together with substantial treatment burden and incomplete delivery.
Clinical interpretation
SWOG 8507 established the importance of maintenance BCG for recurrence prevention after induction in high-risk NMIBC.
The study did not establish a comparable mortality benefit, and it predates modern BCG-shortage strategies and newer bladder-preservation agents.
Toxicity / burden
Maintenance requires repeated intravesical procedures. Historical reports describe substantial grade 3–4 toxicity and incomplete completion of the prescribed schedule.
NNT
Using the 5-year RFS difference, NNT ≈ 6. This is an NNT for preventing recurrence by 5 years, not for preventing progression or death.
Current-practice context · reviewed 14 October 2026
SWOG 8507 established maintenance BCG after induction for patients with high-risk NMIBC who respond to induction, improving recurrence-free outcomes compared with induction alone. Contemporary treatment should follow risk-stratified NMIBC guidance, with adequate induction and maintenance where feasible; BCG supply, tolerability, CIS/high-grade risk and consideration of early cystectomy for very-high-risk disease matter.
SWOG 8507 primary report ↗ · Current guideline guidance ↗