Lamm describes a success story in oncology that he helped create, namely, the favorable therapeutic effect of intravesical bacillus Calmette-Guérin (BCG) against carcinoma in situ (CIS) of the bladder. Virtually every study conducted over the past decade reports complete responses in 70% or more patients treated with BCG, which are often durable for years . Such results have been documented empirically in prospective controlled trials without complete understanding of the mechanism of action of BCG or the optimal dose and treatment regimen. More importantly, not only may BCG eradicate CIS but also it may delay or prevent tumor progression and improve patient survival . Conversely, patients failing to respond to an adequate trial of BCG therapy are at increased risk for disease progression and death from bladder cancer. We now realize that the natural history of CIS in the bladder has been significantly altered by intravesical BCG.