Geographical pattern of carcinoma gallbladder in Bihar and its association with river Ganges and arsenic levels: Retrospective individual consecutive patient data from Regional Cancer Centre

BACKGROUND: Indo-Gangetic basin is known to have higher incidence of gallbladder cancer. Proximity to River Ganga and high heavy metal in soil exposure have been postulated as risk factors. AIM: This study aims to evaluate the geographical pattern of gallbladder cancer from consecutive patient database enrolled in hospital-based cancer registry (HBCR). OBJECTIVES: To evaluate demographic profile and districtwise/zonewise dispersion of gallbladder cancer cases registered in HBCR from year 2014 to 2016. To evaluate association of carcinoma gallbladder (CaGB) due to proximity of Ganges, districts of high soil arsenic levels and referral bias. MATERIALS AND METHODS: Demographic profile and district-based location of individual consecutive gallbladder cancer patient registered in Regional Cancer Centre from the year 2014 till 2016 were analyzed. Population data from 2011 census and arsenic soil content data from central groundwater body were obtained. Frequency distribution, cross tabulation, and odds ratio were used to analyze risk of CaGB across population subsets in Bihar. RESULTS: A total of 1291 consecutive patients of CaGB were registered from 2014 to 2016. Median age at diagnosis was 55 years (range 18–95 years). Male to female ratio was 0.6. Patna (16%) followed by Vaishali (5.8%), Sitamarhi (5%), Madhubani (4.7%), Gaya (4%), and Samastipur (4%) had highest cases. Districts along main central River Ganga (n = 12) and those exposed to high arsenic soil content (n = 15) had higher odds ratio for CaGB, 1.72 (95% confidence interval [CI]: 1.54–1.91, P = 0.001), and 1.45 (95% CI: 1.30–1.62, P = 0.001), respectively. Districts within 100 km radius of our institute had higher gallbladder cancer cases, odds ratio 1.81 (95% CI: 1.62–2.03, P = 0.001), suggesting significant referral bias predominantly contributed by cases registered under Patna and Vaishali districts. CONCLUSION: CaGB is major public health problem in Bihar. Exposure to high soil arsenic levels and proximity to River Ganga are strongly associated with gallbladder cancer. Systematic population-based longitudinal studies are needed to explore above hypothesis.