A risk factor is anything that increases a person’s chance of getting a disease such as cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx, colon, bladder, kidney, and several other organs. But having a risk factor, or even several risk factors, does not necessarily mean that a person will get the disease. Scientists have found several risk factors that make a person more likely to develop gallbladder cancer.

Gallstones and inflammation of the gallbladder: Gallstones are the most common risk factor for gallbladder cancer. Gallstones are hard, rock-like formations of cholesterol and other substances in the gallbladder. Between 75% and 90% of persons with gallbladder cancer have gallstones and chronically inflamed gallbladders when they are diagnosed. People with one or several large (3 cm or 1.2 inches) gallstones are 10 times more likely to develop gallbladder cancer than those with small (1 cm or 0.4 inches) gallstones. However, gallstones are a very common condition and gallbladder cancer is quite rare, especially in the United States. The vast majority of people with gallstones never develop gallbladder cancer.

Porcelain gallbladder: Porcelain gallbladder is a condition in which the wall of the gallbladder becomes covered with calcium deposits. It sometimes occurs after the gallbladder has been severely inflamed. People with this condition may have a high risk of developing gallbladder cancer, although recent studies have tended to cast doubt on this. Doctors may recommend surgery to remove a porcelain gallbladder.

Typhoid: People chronically infected with salmonella (the bacterium that causes typhoid) and those who are carriers of the disease are 6 times as likely to develop gallbladder cancer as those not infected. Typhoid is rare in the United States, with fewer than 600 cases each year.

Choledochal cysts: Choledochal means having to do with the common bile duct, the passageway that carries bile from the liver and gallbladder to the first part of the small intestine. Choledochal cysts are bile-filled sacs that are connected to the common bile duct. They can grow 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 the patient’s risk for developing gallbladder cancer.

Industrial and environmental chemicals: Animal studies indicate that an industrial chemical known as azotoluene and chemical compounds called nitrosamines may cause gallbladder cancer. Workers in rubber plants and metal-fabricating industries have more gallbladder cancers than the general public.

Anomalous pancreatobiliary duct junction and other abnormalities of the bile ducts: The pancreatobiliary junction is the area where the bile duct (passageway carrying fluids from the liver and gallbladder) and the pancreatic duct (passageway carrying digestive juices from the pancreas) join together. An anomalous junction is one that is connected differently than a normal junction. A higher risk is found among people with this abnormality and others that allow very acidic juice from the pancreas to reflux (flow back “upstream”) into the ducts. That backward flow also prevents the bile from being emptied through the bile ducts into the intestines as quickly as normal. Scientists are not sure whether the increased risk is due to the action of the pancreatic juice or possibly due to the ducts being exposed longer to carcinogens in the concentrated bile.

Age: The highest proportion of patients with this cancer are in their 70s.

Family history: Gallbladder cancer can run in families. A history of gallbladder cancer in the family increases a person’s chances of developing this cancer. The risk, however, is still low because this is a rare disease.

Gender: In the United States, gallbladder cancer occurs nearly twice as often in women. Gallstones and gallbladder inflammation, 2 important risk factors for gallbladder cancer, are much more common among women than men.

Gallbladder polyps: A gallbladder polyp is a growth that bulges outward from the surface level of the inner gallbladder wall. Some polyps are formed by a small gallstone embedded in the gallbladder wall. Others may be small tumors (either cancerous or benign) or may be caused by inflammation. Polyps larger than 1 centimeter (a little less than half an inch) are more likely to be malignant, so doctors commonly recommend removal of the gallbladder in patients with gallbladder polyps that size or larger.

Obesity: Patients with gallbladder cancer are more often overweight or obese than people without this disease.

Ethnicity: Native Americans, particularly in the southwestern United States, and Mexican Americans have a high rate of gallbladder cancer. They are also more likely to have gallstones than members of other ethnic and racial groups.

Diet: A high-carbohydrate and low-fiber diet may increase a person’s susceptibility to gallbladder cancer.

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