57Aflatoxin and Extrahepatic Bile Duct Cancer: A Planned Study
Jill Koshiol, Rime Jebai, Ruth Pfeiffer, Ann W Hsing, Yu-Tang Gao, John D GroopmanAbstract
Background & Objectives
Exposure to aflatoxin B1 is known to cause hepatocellular carcinoma, and accumulating evidence suggests it might cause gallbladder cancer as well. The association between extrahepatic bile duct cancer (EHBDC) and aflatoxin B1 has not been explored, however. Animal data demonstrate that aflatoxin can cause bile duct cancer in primates, ducks, and glutathione S-transferase A3 knockout mice. Studies of molecular signatures in cholangiocarcinoma patients have been inconsistent, and null findings might be due to low levels of exposure to aflatoxin in the respective study population. A direct assessment of the association of circulating aflatoxin B1-lysine adduct levels (considered to be the most robust detection method for aflatoxin exposure) with EHBDC in humans is needed.
Method
We plan to assess this association using samples from the Shanghai Biliary Tract Cancer Case-Control Study. We will test serum samples from 142 EHBDC cases and 284 population-based controls for circulating aflatoxin B1-lysine adducts using isotope dilution mass spectrometry. Although aflatoxin contamination has been dramatically reduced in China, the Shanghai Biliary Tract Cancer case control study was conducted in June 1997-May 2001, before the major drop-off. Given that we have previously detected aflatoxin B1-lysine in this study population using the same technology (32% in gallbladder cancer cases and 15% in gallstone controls), we expect sufficient levels to be able to assess the association between aflatoxin B1-lysine adducts and EHBDC. This study will provide the first direct evaluation of aflatoxin exposure and EHBDC in humans.