Niwa N, et al. - An exploration was conducted of the consequence of the purified protein derivative (PPD) skin test prior to bacillus Calmette-Guerin (BCG) therapy in patients with non-muscle-invasive bladder cancer (NMIBC) treated with adjuvant BCG therapy. The therapeutic effects of BCG therapy were enhanced due to the PPD skin test prior to BCG therapy. It potentially led to a higher incidence of major BCG-related side effects. Findings disclosed that an improvement could be yielded in the oncological outcomes of BCG therapy via the combination therapy using BCG with the PPD skin test.