Arsenic level in bladder tumor of patients from an exposed population: association with progression and prognosis.

Aims: To elucidate the impact of arsenic on progression and prognosis of bladder cancer. Patients & methods: Total arsenic in 145 tumors (80 non-muscle-invasive [NMIBC] and 65 muscle-invasive bladder cancer [MIBC]) was measured and associated with Ki67 expression, tumor-clinicopathological parameters and patient outcome. Results: Tumor arsenic concentration was higher in exposed than unexposed patients (256 μg/kg vs 77 μg/kg; p < 0.0001) and positively correlated (r = 0.65; p < 0.0001) with arsenic content of patient's drinking water. Arsenic concentration showed significant association with Ki67-overexpression (p = 0.001) and advanced tumor stages (NMIBC vs MIBC; p = 0.0009). In NMIBC, high tumor arsenic (>100 μg/kg) and Ki67 overexpression was established as predictors for recurrence (hazard ratio [HR]: 4.68; p = 0.005 and HR: 3.91; p = 0.018) and progression (HR: 6.04; p = 0.023 and HR: 6.87; p = 0.013). In MIBC, association of high arsenic remained significant with increased risk of recurrence (HR: 4.58; p = 0.04). Conclusion: In NMIBC, high arsenic and Ki67 overexpression and in MIBC, only high arsenic showed prognostic importance in predicting poor patient outcome.