What are the risk factors for gallbladder cancer?

A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx (voice box), colon, bladder, kidney, and several other organs.

But risk factors don't tell us everything. Having a risk factor, or even several risk factors, does not necessarily mean that a person will get the disease. And many people who get the disease may not have any known risk factors.

Scientists have found several risk factors that make a person more likely to develop gallbladder cancer. Many of these are related in some way to chronic inflammation in the gallbladder.

Gallstones

Gallstones are the most common risk factor for gallbladder cancer. Gallstones are hard, rock-like formations of cholesterol and other substances that form in the gallbladder and can cause chronic inflammation. At least 3 out of 4 people with gallbladder cancer have gallstones when they are diagnosed. Gallstones are a very common condition, but gallbladder cancer is quite rare, especially in the United States. Most 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 long-term inflammation of the gallbladder. People with this condition may have a higher risk of developing gallbladder cancer (possibly because both conditions can be related to inflammation). Still, not all studies have found such a link.

Female gender

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

Obesity

Patients with gallbladder cancer are more often overweight or obese than people without this disease. Obesity is also a risk factor for gallstones, which may help explain this link.

Older age

Gallbladder cancer can occur in younger people, but it’s seen mainly in older people. The average age of people when they are diagnosed is 73. Almost 3 out of 4 people with gallbladder cancer are older than age 65 when it is found.

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 Asian, Eastern European, 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 over time and may contain as much as 1 to 2 quarts of bile. The cells lining the sac often have areas of pre-cancerous changes, which increase a person's risk for developing 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 abnormalities where these ducts meet that allow juice from the pancreas to 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 whether the increased risk is due to the action of the pancreatic juice or 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 out 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 1 centimeter (almost a half inch) are more likely to be cancerous, so doctors often advise removing the gallbladder in patients with gallbladder polyps that size or larger.

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 a difficult area 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 workers in the rubber and textile industries may have more gallbladder cancers than 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 develop gallbladder cancer than those not infected. 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.