Bacillus Calmette-Guérin (BCG) treatment for non-muscle-invasive bladder cancer frequently causes an intraprostatic BCG granuloma. We investigated the optimal timing for a prostate biopsy after BCG treatment by retrospectively analyzing the cases of 22 patients with non-muscle-invasive bladder cancer who underwent a prostate biopsy after BCG treatment at our institute (2013-2017). Biopsies were indicated for a rising prostate-specific antigen (PSA) level, positive digital rectal examination findings, or the appearance of de novo low apparent diffusion coefficient lesions on MRI. The control group was comprised of 28 age- and PSA-matched patients. The relationships among the cancer detection rate and the patients' PSA levels and MRI findings were analyzed. Prostate cancer was detected by biopsy in only 13.9% (3/22) of the patients in the BCG group but in 78.5% (22/28) of the control patients (p=0.0001). The three patients in the BCG group in whom prostate cancer was detected had all undergone the biopsy > 1 year after their BCG treatment. The remaining biopsies were performed within 1 year after BCG treatment and resulted in no diagnoses of prostate cancer. We suggest that performing a prostate biopsy early after BCG treatment is not informative or useful.
Keywords: bacillus Calmette-Guérin; bladder cancer; prostate biopsy; prostate cancer; prostate granuloma.