Risk Factors

Ethnicity and geography

In the United States, the risk of developing gallbladder cancer is highest among Mexican Americans and Native Americans. They are also more likely to have gallstones than members of other ethnic and racial groups. The risk is lowest among African Americans. Worldwide, gallbladder cancer is much more common in India, Pakistan, and CentralEuropean and South American countries than it is in the United States.

Choledochal cysts

Choledochal cysts are bile-filled sacs that are connected to the common bile duct, the tube that carries bile from the liver and gallbladder to the small intestine. (Choledochal means having to do with the common bile duct.) The cysts can grow large over time and may contain as much as 1 to 2 quarts of bile. The cells lining the sac often have areas of precancerous changes, which increase a person’s risk for gallbladder cancer.

Abnormalities of the bile ducts

The pancreas is another organ that releases fluids through a duct into the small intestine to help digestion. This duct normally meets up with the common bile duct just as it enters the small intestine. Some people have an abnormality where these ducts meet that lets juice from the pancreas reflux (flow backward) into the bile ducts. This backward flow also prevents the bile from being emptied through the bile ducts as quickly as normal. People with these abnormalities are at higher risk of gallbladder cancer. Scientists are not sure if the increased risk is due to the action of the pancreatic juice or is possibly due to the ducts being exposed longer to damaging substances in the bile itself.

Gallbladder polyps

A gallbladder polyp is a growth that bulges from the surface of the inner gallbladder wall. Some polyps are formed by cholesterol deposits in the gallbladder wall. Others may be small tumors (either cancerous or benign) or may be caused by inflammation. Polyps larger than 1centimeter(almost a half inch) are more likely to be cancer, so doctors often recommend removing the gallbladder in patients with gallbladder polyps that size or larger.

Primary sclerosing cholangitis

In primary sclerosing cholangitis (PSC), there is inflammation and scarring of the bile ducts. People with this disease have an increased risk of cancer of the gallbladder and bile ducts. Many people with PSC also have ulcerative colitis, a type of inflammatory bowel disease.

Industrial and environmental chemicals

It is not clear if exposure to certain chemicals in the workplace or the environment increases the risk of gallbladder cancer. This is hard to study because this cancer is not common. Some studies in lab animals have suggested that chemical compounds called nitrosamines may increase the risk of gallbladder cancer. Other studies have found that gallbladder cancer might occur more in workers in the rubber and textile industries than in the general public. More research is needed in this area to confirm or refute these possible links.

Typhoid

People chronically infected with salmonella (the bacterium that causes typhoid) and those who are carriers of the disease are more likely to get gallbladder cancer than those not infected. This is probably because the infection can cause gallbladder inflammation. But typhoid is rare in the United States.

Family history

Most gallbladder cancers are not found in people with a family history of the disease. A history of gallbladder cancer in the family seems to increase a person’s chances of developing this cancer, but the risk is still low because this is a rare disease.