The gallbladder lies just under the liver in the upper abdomen. The gallbladder stores bile, a fluid made by the liver that helps digest fat.
Almost all gallbladder cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).
Gallbladder cancer is hard to diagnose in the early stages because there are no signs or symptoms. Gallbladder cancer may be found when the gallbladder is checked for gallstones or removed.
Gallbladder Cancer. National Cancer Institute. Bethesda, MD, https://www.cancer.gov/types/gallbladder