I excerpted this from the European Guidelines for treatment of Ta,T1 tumors and CIS,high grade tumors only (the previous section said there is not evidence of this applying to intermediate and low grade tumors) giving the reference (34) about the meta-analysis published in '02 in the J of U.
If anyone would like a copy of either the guidelines or the meta-analysis, I have pdf copies of the full articles, write me privately and I'll email.
5.4.2 BCG can delay or prevent progression to muscle-invasive disease Although BCG is superior to chemotherapy in preventing recurrences (45), controversy existed until recently as to whether BCG could delay or prevent progression to muscle-invasive disease. A meta-analysis carried out by
the EORTC has provided a clinically relevant answer to this question (34) (level of evidence: 1). A total of 24 randomized trials were identified with follow-up information on progression for 4,863 patients. A total of 3,967 (81.6%) patients had only papillary tumours and 896 (18.4%) had primary or concomitant CIS. Five different BCG strains were used, and in 20 out of the 24 trials some form of BCG maintenance was used. In four trials only, a 6-week induction course was used. Based on a median follow-up of 2.5 years and a maximum of 15 years, 260 out of 2,658 patients (9.8%) on BCG progressed compared to 304 out of 2,205 (13.8%) in the control groups (TUR alone, TUR plus intravesical chemotherapy, or TUR plus another immunotherapy). This result is a reduction of 27% in the risk of progression with BCG treatment (p = 0.0001). The size of the reduction is similar in patients with Ta,T1 papillary tumours and in those with CIS.
5.4.3 Maintenance therapy is necessary for optimal efficacy
In this same meta-analysis (34), only patients receiving maintenance BCG benefited. In the four trials where no maintenance was given, no reduction of progression was observed. In the 20 trials in which some form of BCG maintenance was given, a reduction of 37% in the risk of progression was observed (p = 0.00004). The metaanalysis was unable to determine which BCG maintenance schedule was the most effective. In their metaanalysis, Bohle et al. (45) concluded that at least 1 year of maintenance BCG was required to show the superiority of BCG over mitomycin C in preventing recurrence.
45. Bohle A, Jocham D, Bock PR. Intravesical bacillus Calmette-Guerin versus mitomycin C for superficial bladder cancer: a formal meta-analysis of comparative studies on recurrence and toxicity. J Urol 2003;169:90-95.
34. Sylvester RJ, van der Meijden, Lamm DL. Intravesical bacillus Calmette-Guerin reduces the risk of progression in patients with superficial bladder cancer: a combined analysis of the published results of randomized clinical trials. J Urol 2002;168:1964-1970.