Characteristics of arsenic-related bladder cancer: A study from Nationwide Cancer Registry Database in Taiwan

Abstract

Objective: To investigate the clinical and pathological characteristics of arsenic-related bladder cancer. Methods: From 2008 through 2011, data on 7699 patients with bladder cancer were extracted from the Taiwan Cancer Registry Database. A diagnosis of bladder cancer (International Statistical Classification of Diseases and Related Health Problems, 9th Revision: 188) was confirmed in all patients. Using birth residency codes, patients were divided into three groups: the core zone (CZ; an arsenic endemic area with well water arsenic levels of 350–1100 ng/mL); zone 1 (Z1; an area with well water arsenic levels of≥350 ng/mL but not a blackfoot disease-endemic area); and zone 2 (Z2; an area with well water arsenic levels of<350 ng/mL). Clinicopathological characteristics and survival outcomes were compared between the three groups. Results: In this cohort, 119 (1.5%), 1145 (14.9%), and 6435 (83.6%) patients were born in the CZ, Z1, and Z2, respectively. A higher proportion of female patients (35.3%, 31.4%, and 27.5%; p = 0.014) and lower smoking rates (29%, 34.8%, and 35.9%; p = 0.694) were noted in the CZ compared with Z1 and Z2. CZ patients had more high-grade differentiated (80.9%, 69.9%, and 63.0%; p < 0.001) and high clinical stage (stages II–IV, 52.8%, 38.1%, and 31.8%; p < 0.001) tumors compared with Z1 and Z2 patients. Radical cystectomy was infrequently performed for clinical stage II (19.6%) and stage III (25.2%) bladder cancer patients. CZ patients had significantly shorter overall and cancer-specific survival durations compared with Z1 and Z2 patients. Older age, female sex, higher tumor grade or stage, and higher arsenic levels were associated with both poorer overall and cancer-specific survival in a multivariate analysis with a Cox proportional model. Conclusion: In Taiwan, patients with arsenic-related bladder cancer may have poorer tumor characteristics and decreased overall and cancer-specific survival rates