Gallbladder cancer is a cancer that starts in the gallbladder. In order to understand this cancer, it helps to know about the normal structure and function of the gallbladder.
About the gallbladder
The gallbladder is a small, pear-shaped organ located under the right lobe of the liver. Both the liver and the gallbladder are behind the right lower ribs. The gallbladder is usually about 3 to 4 inches long and normally no wider than 1 inch.
The gallbladder concentrates and stores bile, a fluid made in the liver. Bile helps digest the fats in foods as they pass through the small intestine. Bile may be released from the liver directly into the small intestine, or it may be stored in the gallbladder and released later. When food (especially fatty food) is being digested, the gallbladder contracts and releases bile through a small tube called the cystic duct. The cystic duct joins up with the hepatic duct, which comes from the liver, to form the common bile duct. The common bile duct empties into the small intestine.
The gallbladder is helpful, but it is not essential for life. Many people live normal lives after having their gallbladders removed.
Types of gallbladder cancers
More than 9 out of 10 gallbladder cancers are adenocarcinomas. An adenocarcinoma is a cancer that starts in cells with gland-like properties that line many internal and external surfaces of the body (including the inside of the digestive system).
A type of gallbladder adenocarcinoma that deserves special mention is called papillary adenocarcinoma (or just papillary cancer). These are gallbladder cancers whose cells are arranged in finger-like projections when viewed under a microscope. In general, papillary cancers are not as likely to invade the liver or nearby lymph nodes. They tend to have a better prognosis (outlook) than most other kinds of gallbladder adenocarcinomas. About 6% of all gallbladder cancers are papillary adenocarcinomas.
There are other types of cancer that can develop in the gallbladder, such as adenosquamous carcinomas, squamous cell carcinomas, and small cell carcinomas, but these are uncommon.
Researchers have found several risk factors that make a person more likely to develop gallbladder cancer (see the section, "What are the risk factors for gallbladder cancer?"). They are also making progress in understanding how some of these risk factors lead to gallbladder cancer.
Most doctors studying the subject think that chronic inflammation is the major cause of gallbladder cancer. When gallstones are present, the gallbladder may release bile more slowly. This means that gallbladder tissue is exposed to the bile for longer than usual. This may lead to irritation and inflammation. Scientists also suspect that this longer exposure to possible cancer-causing substances in the bile could also be responsible. Certain abnormalities in the ducts that carry fluids from the gallbladder and pancreas to the small intestine can cause juices from the pancreas to flow backward into the gallbladder and bile ducts. Researchers suspect that this reflux (backward flow) of pancreatic juices may irritate the cells lining the gallbladder and bile ducts in a way that causes irritation and inflammation. This may stimulate their growth and perhaps make them more sensitive to cancer-causing substances.
Scientists have begun to understand how risk factors such as inflammation may lead to certain changes in the DNA of cells, causing them to grow abnormally and form cancers. DNA is the chemical in each of our cells that makes up our genes -- the instructions for how our cells function. We usually look like our parents because they are the source of our DNA. However, DNA affects more than how we look.
Some genes contain instructions for controlling when cells grow and divide. Genes that promote cell division are called oncogenes. Genes that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA changes (mutations) that turn on oncogenes or turn off tumor suppressor genes.
Some people inherit DNA mutations from their parents that greatly increase their risk for certain cancers. But inherited gene mutations are not believed to cause very many gallbladder cancers.
Gene mutations related to gallbladder cancers are usually acquired during life rather than being inherited. For example, acquired changes in the p53 tumor suppressor gene are found in most cases of gallbladder cancer. Other genes that may play a role in gallbladder cancers include k-ras, b-RAF, FHIT, CDKN2, and HER2.
Many newer cancer drugs target cells with specific gene changes. Knowing which genes are abnormal in gallbladder cancer cells may help doctors determine which of these new drugs might be effective.
Can Gallbladder Cancer Be Found Early?
Only about 1 out of 3 gallbladder cancers are found before they have spread to other tissues and organs. Many of these early cancers are found unexpectedly when a person's gallbladder is removed as treatment for gallstones. When the gallbladder is looked at in the lab after it is removed, small cancers or pre-cancerous changes are sometimes found that did not cause any symptoms.Because the gallbladder is located deep inside the body, early tumors cannot be seen or felt by health care providers during routine physical exams. There are currently no blood tests or other tests that can reliably detect gallbladder cancers early enough to be useful as screening tests. Without effective screening tests, most gallbladder cancers are found only when the cancer has grown enough to cause symptoms.
How Is Gallbladder Cancer Treated?
This information represents the views of the doctors and nurses serving on the American Cancer Society's Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.
The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.
Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don't hesitate to ask him or her questions about your treatment options.
The first part of this section describes the various types of treatments used for gallbladder cancers. This is followed by a description of the most common approaches used for these cancers based on different situations.
Making treatment decisions
After gallbladder cancer is found and staged, your cancer care team will discuss your treatment options with you. It is important for you to take time and think about your choices. In choosing a treatment plan, factors to consider include the type and stage of the cancer, the likely side effects of treatment, your overall health, and the chances of curing the disease, extending life, or relieving symptoms.
If time permits, it is often a good idea to seek a second opinion, particularly for an uncommon cancer such as gallbladder cancer. A second opinion can provide more information and help you feel more confident about your chosen treatment plan.
Nearly all doctors agree that surgery offers the only reasonable chance for curing people with gallbladder cancer. But there are differences of opinion about how advanced a gallbladder cancer may be and still be curable. Therefore, it may be especially important for people with gallbladder cancer to seek a second opinion when considering treatment options. Finding a doctor experienced in treating this disease may have other benefits as well. Most studies have found that more extensive surgeries tend to result in higher survival rates, but such operations are most often done at major cancer centers and may not be available in every community.
In general, spread of the cancer beyond the gallbladder does not make it incurable by surgery unless the cancer has spread too far or into major blood vessels. For instance, if the cancer has invaded the liver -- but only in one area and not too deeply -- it may be possible to remove all of the cancer by surgery. If the cancer has spread to both sides of the liver, to the lining of the abdominal cavity, to organs farther away from the gallbladder than the liver, or if it surrounds a major blood vessel, surgery is unlikely to remove it all.
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