Abstract 3431: Genetically determined circulating lactase/phlorizin hydrolase concentrations and risk of colorectal cancer: A two-sample mendelian randomization study

Abstract Background: Colorectal cancer (CRC) ranks as the third most common cancer worldwide. Despite its established connection with genetic, dietary, and lifestyle factors, gaps remain in the understanding of its etiology. Lactase-phlorizin hydrolase (LPH) plays a critical role in milk digestion and influences crucial nutrient absorption and gut microbiota composition. A direct relationship of CRC risk with LPH level remains unexplored. Our study aims to elucidate the potential causal link between genetically determined LPH levels and CRC risk. Methods: We applied a two-sample Mendelian Randomization (MR) strategy to investigate the causal link between elevated LPH levels and CRC risks. Genetic instruments for LPH (one cis-variant and three trans-variants) were derived from the Fenland Study, and CRC-associated summary statistics for these instruments were extracted from the FinnGen Study, PLCO Atlas Project, and Pan-UK Biobank. Primary MR analyses focused on a cis-variant (rs4988235) for LPH levels, with results integrated via meta-analysis. MR analyses using all variants were also undertaken. This analytical approach was further extended to assess CRC subtypes, specifically colon and rectal cancer. Results: Meta-analysis across the three datasets illustrated an inverse association between genetically predicted LPH level and CRC risk (OR: 0.92 [95% CI, 0.89-0.95]). Subtype analyses revealed associations of genetically predicted elevated LPH levels with reduced risks for both colon cancer (OR: 0.92 [95% CI, 0.89-0.96]) and rectal cancer (OR: 0.92 [95% CI, 0.87, 0.98]). Consistency was observed across varied analytical methods and different datasets. Conclusions: Our study suggests an inverse relationship between genetically determined LPH level and CRC risk. Further exploration is warranted to unveil the underlying mechanisms and validate LPH’s potential role in CRC prevention. Citation Format: Sihao Han, Jiemin Yao, Hajime Yamazaki, Samantha Streicher, Jianyu Rao, Roch Nianogo, Zuo-Feng Zhang, Brian Huang. Genetically determined circulating lactase/phlorizin hydrolase concentrations and risk of colorectal cancer: A two-sample mendelian randomization study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3431.