Complications of intravesical bcg immunotherapy for bladder cancer

Bladder cancer is the sixth most common cancer in the United States, and 70% of cases are non–muscle invasive. Intravesical bacillus Calmette-Guérin (BCG) immunotherapy, administered after transurethral tumor resection, is the most effective adjuvant treatment for intermediate-and high-grade non–muscle-invasive bladder cancer. Despite its weakened state, BCG has the potential to cause multisystem disease in treated patients. Although minor side effects following BCG administration are common, complications are rare. The pathogenesis of BCG-related disease may be active infection or a hypersensitivity reaction, and complications can involve many organ systems. Local complications result from BCG-contaminated urine and affect the genitourinary system. Systemic complications are the result of BCG dissemination in the bloodstream, and they may be musculoskeletal, vascular, pulmonary, or hepatic or involve other organ systems. Because the imaging findings of BCG-related complications can mimic those of cancer or infection by another organism, knowledge of prior BCG therapy and awareness of the potential related complications are essential for making the correct diagnosis prospectively and guiding appropriate treatment without delay.