[Study on the therapy of nonmuscle-invasive bladder cancer: treatment of nonmuscle-invasive high-grade urothelial cancer of the bladder with the standard number and dosage of intravesical BCG instillations versus a reduced number of intravesical BCG instillations in the standard dosage: a randomized phase 3 study of the European Association of Urology Research Foundation (NIMBUS - AB 37/10 of the AUO)].