Abstract C018: Urinary Arsenic and Other Heavy Metals in Gallbladder Cancer Patients: A Pilot Study Correlating Exposure with Drinking Water and Assessing Carcinogenic Risk in Northeast India

Abstract Introduction: Gallbladder cancer (GBC) incidence is disproportionately high in Northeast India, and the second most affected epidemiological region in the world, where the contribution of environmental factors like heavy metals remains understudied. Aims: To investigate the association between exposure to arsenic and other heavy metals in drinking water and urine with the risk of gallbladder cancer. Methods: This cross-sectional study, with institutional ethical approval, included 201 histopathologically confirmed GBC patients from a tertiary cancer hospital in Northeast India. Spot urine samples (N=201) and paired drinking water samples (N=100) were analyzed for twelve metals using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analytical method was validated for precision (%RSD 5%) and accuracy (85–109%). Statistical analysis involved non-parametric tests (Mann-Whitney U, Kruskal-Wallis) and Spearman's correlation, with health risks assessed using the US EPA model. Results: Urinary analysis of 201 patients revealed high mean concentrations of selenium (83. 51 µg/L), strontium (84. 40 µg/L), and arsenic (20. 97 µg/L). In 100 drinking water samples, arsenic levels reached a maximum of 476. 38 µg/L (48 times the WHO limit), while lead and nickel exceeded safety thresholds in 22% and 18% of samples, respectively. The total carcinogenic risk was 400-fold higher than EPA safety limits (4. 0 × 10-3), and the non-carcinogenic Hazard Index (HI) from urine was 3. 51, primarily driven by arsenic (HQ=2. 44). Significant positive correlations were observed between urinary arsenic-selenium (r=0. 504, p0. 01) and cadmium-selenium (r=0. 552, p0. 01). Females exhibited significantly higher urinary concentrations of vanadium, chromium, and nickel (p0. 05). Fish consumption and smoking were found to significantly influence metal accumulation. Conclusions: This study provides novel evidence directly linking multi-metal exposure, particularly from contaminated drinking water to the risk of GBC. The findings underscore an urgent need for public health interventions focused on improving water quality, specifically targeting arsenic, and for further longitudinal research to confirm a causal relationship between heavy metal exposure and GBC. Citation Format: Christy Thomas, Gaurav Das, Munlima Hazarika, Nilotpal Saharia, Krishna Undela. Urinary Arsenic and Other Heavy Metals in Gallbladder Cancer Patients: A Pilot Study Correlating Exposure with Drinking Water and Assessing Carcinogenic Risk in Northeast India abstract. In: Proceedings of the AACR Special Conference in Cancer Research: The Rise in Early-Onset Cancers—Knowledge Gaps and Research Opportunities; 2025 Dec 10-13; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2025;31 (23Suppl): Abstract nr C018.