Purified protein derivative skin test reactions are associated with clinical outcomes of patients with nonmuscle invasive bladder cancer treated with induction bacillus Calmette-Guérin therapy

Objectives: To investigate the relationship between purified protein derivative (PPD) skin test reactions before bacillus Calmette-Guérin (BCG) therapy and the clinical outcomes of BCG-naïve nonmuscle invasive bladder cancer patients treated with adjuvant BCG therapy. Materials and methods: A total of 288 nonmuscle invasive bladder cancer patients subjected to the PPD skin test before BCG therapy were included. PPD skin test reactions were categorized into 3 groups: positive, slightly positive, and negative. The presence of an induration was positive. If an induration was absent, erythema of 10. mm or more and less than 10. mm corresponded to slightly positive and negative, respectively. Results: A total of 66 (22.9%), 149 (51.7%), and 73 (25.3%) patients exhibited a positive, slightly positive, and negative to PPD skin test, respectively. The 5-year recurrence-free survival rate of patients with positive PPD skin test reactions was 89.4 ± 4.1%, which was significantly higher than those of patients with slightly positive (65.5 ± 4.2%, P = 0.001) and negative reactions (56.4 ± 6.6%, P<0.001). A multivariate Cox regression analysis revealed that a positive PPD skin test reaction was independently associated with tumor recurrence (hazard ratio of 0.233, P<0.001), but not with stage progression. The incidence of fever persisting for more than 2 days or fever of ≥38°C was significantly higher in patients with a positive PPD skin test reaction (18.2%) than in patients with slightly positive (8.7%) and negative PPD skin test reactions (4.1%). Conclusions: The PPD skin test reactions before BCG therapy may predict clinical outcomes following BCG therapy and help clinicians counsel patients exhibiting strong therapeutic effects with BCG therapy and potentially major BCG-related side effects.