About Pancreatic Cancer
The pancreas is located behind the stomach, extending horizontally across the middle of the abdomen. Its shape is often described as a long fish, because it is wide at one end (commonly referred to as the “head” of the pancreas) and narrow at the other (the “tail”). Overall, it is about six inches long and two inches wide.
The pancreas is very complex, functioning as two separate glands (exocrine and endocrine) inside the same organ.The vast majority of pancreatic cells function as exocrine glands and ducts.The exocrine glands make pancreatic juice, which contains enzymes that break down fats, proteins and carbohydrates in food.This enables nutrients from the food we eat to be absorbed by the small intestine.The exocrine ducts carry the pancreatic juice to the small intestine, via the common bile duct.
Less than five percent of pancreatic cells function as endocrine cells. These cells are known as islets, or islets of Langerhans.They produce two hormones, insulin and glucagon, which help control the amount of sugar in the blood. Both exocrine and endocrine cells in the pancreas can form tumors.However, those formed in the exocrine pancreatic cells are far more common. Cancer of the pancreas is the fourth leading cause of cancer death in men and women.
What are the different types of pancreatic cancer?
The exocrine and endocrine cells of the pancreas form very different types of tumors. Because 90 percent of pancreatic tumors originate in the exocrine cells, the information presented in this pamphlet focuses only on exocrine cancers.
Note:Additional information about endocrine cancers can be obtained from the National Cancer Institute by calling 1-800-422-6237.
About 95 percent of exocrine cancers are adenocarcinomas.These cancers usually start in the ducts of the pancreas, though they can also begin in the cells that produce pancreatic enzymes, the acinar cells. The less common types of exocrine pancreatic cancers include adenosquamous carcinoma, squamous cell carcinoma, and giant cell carcinoma. Exocrine pancreatic cancers (referred to as pancreatic cancer in the remainder of this pamphlet) are usually treated according to the stage of the cancer rather than the exact type.
What are the risk factors for pancreatic cancer?
Age: As with all cancers, the risk of pancreatic cancer increases with age. Most people diagnosed with pancreatic cancer are between age 60 and 80.
Smoking: About 30 percent of pancreatic cancers are related to smoking.
Gender: Men’s risk is about 30 percent higher than women’s.
Diet: A diet high in meats and saturated fats raises risk. A diet rich in fruits, vegetables and dietary fiber seems to be protective. In part, this may be because obesity is a risk factor for pancreatic cancer, and a diet high in fruits, vegetables and fiber helps weight-control efforts. Past research suggested that drinking a lot of coffee or alcohol could raise pancreatic cancer risk. However, recent research has not confirmed this link.
Diabetes: Pancreatic cancer is more common among people with diabetes. However, it is not yet clear whether diabetes is actually a risk factor or whether damage caused by pancreatic cancer is responsible for the diabetes.
Chronic pancreatitis: Long-term inflammation of the pancreas, known as chronic pancreatitis, raises risk. Recent research attributes this to the fact that patients with pancreatitis frequently have other risk factors for pancreatic cancer, such as smoking. It is important to note that most patients with chronic pancreatitis never get cancer. However, a small number of pancreatitis cases seem to be caused by an inherited gene defect (mutation).This familial form of pancreatitis confers a very high risk for developing cancer of the pancreas—about a 40–75 percent lifetime risk.
Family history: A history of pancreatic cancer in the family increases the likelihood of developing the disease. An inherited predisposition to developing pancreatic cancer appears to be a factor in only about 5–10 percent of cases, however. But genetic mutations associated with increased pancreatic cancer risk are also associated with an increased risk for other cancers. Some of these genetic mutations can now be recognized by genetic testing. Discuss this option with your physician.
Exposure to certain chemicals: Prolonged occupational exposure to certain chemicals, including some pesticides, dyes, and compounds related to gasoline, may be associated with an elevated risk of pancreatic cancer.
Can anything be done to prevent pancreatic cancer?
The leading controllable risk factor for cancer of the pancreas is smoking. Avoid it! Reducing consumption of meats and fats, eating at least five servings of fruits and vegetables a day, and including six servings of grains in one’s daily diet are other effective preventive strategies. A healthy diet will prevent many types of cancer as well as other diseases, such as heart disease.
What are the signs and symptoms of pancreatic cancer?
Unfortunately, most people with pancreatic cancer do not exhibit any signs or symptoms until the cancer has progressed to a late stage. When symptoms do appear, they may include:
Jaundice: Jaundice is a yellow coloration of the skin and eyes.This condition can also be caused by a number of noncancerous conditions.
Pain: Pain in the stomach area or the middle to upper back may be a symptom of advanced pancreatic cancer. Of course, this symptom can also be caused by numerous conditions other than cancer.
Weight loss, fatigue: Unexplained weight loss, loss of appetite and fatigue can all be signs of pancreatic cancer.
Digestive difficulties: If a tumor blocks the release of pancreatic juice into the intestine, it can cause problems with digesting fats. This may result in a change in the appearance of stools, making them pale, bulky and greasy.
Enlarged gallbladder: If the bile duct becomes blocked, this can lead to the accumulation of bile in the gallbladder, causing it to swell.
Blood clots: On rare occasions, pancreatic cells may release certain substances that can cause blood clots.
Problems with blood sugar: Pancreatic cancer can lead to problems with sugar metabolism that can be identified by certain blood tests (even though the problems do not cause symptoms of diabetes). On rare occasions, pancreatic cancer can lead to diabetes (high blood sugar levels).
What tests are used to diagnose pancreatic cancer?
Pancreatic cancer is very difficult to diagnose early. The cancer is located so deep within the body that a physician cannot feel a tumor. Moreover, there are presently no blood or imaging tests that can detect pancreatic cancer early, before symptoms appear. By the time symptoms appear, the cancer has usually already spread to other organs.
If pancreatic cancer is suspected, several methods can help in making the diagnosis. A complete medical interview to look for risk factors and symptoms should be performed. Then a thorough physical exam should be done to check for various signs of cancer, such as swollen lymph nodes.
Several diagnostic tests may be used, most of them imaging tests to produce pictures of the pancreas and the surrounding organs.One of the most valuable tests is computed tomography (CT scan), in which specialized x-rays are put together by a computer to create detailed cross-sectional images of the body.
Other imaging tests include: ultrasonography (ultrasound), which uses sound waves to generate images of the targeted area. Generally, a CT scan is more useful than an ultrasound for getting an accurate diagnosis of pancreatic cancer.
Magnetic resonance imaging (MRI), in which images are produced using a magnetic field.MRI is used most often to determine whether major blood vessels located near the pancreas are compressed or invaded by the cancer.
Endoscopic retrograde cholangiopancreatography (ERCP) — a procedure in which a flexible viewing tube (endoscope) is passed down the patient’s throat, into the stomach, and then into the first part of the small intestine. The doctor injects a small amount of dye through the endoscope into the common bile duct. When x-rays are taken, the dye highlights the bile duct and the pancreatic duct. The images reveal any blockages of the ducts that may be caused by a tumor.
Angiography — an x-ray procedure for examining blood vessels — may be done to examine the blood vessels in the area where a tumor is suspected of growing. The angiography can highlight any distortions of blood vessels that may be caused by a tumor or any abnormal arteries that may have grown to supply blood to a tumor. In addition, the doctor may order certain blood tests. Substances that are frequently elevated in the blood of people with certain cancers will likely be measured. These substances are known as tumor markers. In people with pancreatic cancer, the tumor markers CA 19-9 and/or carcinoembryonic antigen (CEA) are often, though not always, elevated.
A biopsy will also be done.During a biopsy, the doctor removes a small sample of tissue for examination under a microscope.There are several types of biopsies that can be done but, nowadays, fine needle aspiration biopsy (FNA) is the most common procedure. FNA biopsy involves the insertion of a very thin needle through the skin into the pancreas. FNA does not require general anesthesia.
If pancreatic cancer is diagnosed,more tests will be performed to determine the extent of the disease (for example, bone scans).This is called staging.The stage of a cancer is the most significant factor in deciding on treatment. For pancreatic cancer, it is even more important than the exact type of cancer.
What are the stages of pancreatic cancer?
Two systems may be used to stage the disease.The first is the TNM system (also known as the American Joint Committee on Cancer, or AJCC, system).The “T” stands for tumor and indicates the extent to which the tumor has spread within the pancreas and to surrounding organs.The “N” indicates whether the cancer has spread to nearby lymph nodes— small collections of immune system cells that help fight infections—and how large those lymph nodes are. And the “M” tells whether the cancer has spread (metastasized) to distant organs in the body or to lymph nodes. The TNM system categorizes the cancer in stages 0 through IV (0-4). The higher the stage number, the more the cancer has spread. The second staging system is simpler (and less precise) than the TNM system, but it is often preferred by surgeons. It classifies the pancreatic cancer in one of three stages:
Resectable: The surgeon is able to remove all visible parts of the tumor.
Locally advanced: Although the cancer has not yet spread to distant organs, it has spread to surrounding tissues in such a way that complete removal of the cancer is not possible. (The tumor is unresectable.) In pancreatic cancer, this is most common when the tumor has spread to large blood vessels nearby.
Metastatic: The cancer has spread to distant organs.
How is pancreatic cancer treated?
Treatment depends on the stage of the disease, the condition of the pancreas, and the patient’s age and overall health.The three main treatment methods are surgery, radiation therapy and chemotherapy. Hormone therapy is currently under investigation. A combination of treatments is often recommended.
Surgery is performed for one of two reasons. Potentially curative surgery is done if there is a high probability that the surgeon will be able to successfully remove all of the visible cancer.When the cancer is too widespread to be removed,“palliative” surgery may be done to relieve symptoms or prevent complications, such as blockage of the bile duct by a tumor.
There are three surgical methods used for potentially curative surgery. The most common is pancreaticoduodenectomy (also known as the Whipple procedure).This usually involves removal of the head of the pancreas, though sometimes the entire pancreas is taken out. In addition, part of the stomach, the first part of the small intestine (the duodenum), some of the second part of the small intestine (the jejunum), nearby lymph nodes, the gallbladder, and part of the common bile duct are removed.The remainder of the bile duct is attached to the small intestine, so that bile from the liver can flow into the small intestine.
There are two other surgical options, but they are not used very often for exocrine pancreatic cancer. These are: distal pancreatectomy, in which the tail of the pancreas and the spleen are removed, and total pancreatectomy, in which the entire pancreas and the spleen are removed.
Palliative surgical procedures usually focus on clearing or preventing bile duct obstruction. In one approach, a small length of tubing (a stent) is inserted into the bile duct to help keep it open when a tumor is exerting a compressive force on it. Another approach is to reroute the flow of bile from the liver directly into the small intestine, instead of letting it travel through the bile duct first.
Radiation therapy, in which high-energy rays are used to kill cancer cells, may be used either before surgery to shrink the tumor or after surgery to destroy any remaining cancer cells. Radiation therapy may also be administered in conjunction with chemotherapy [see below] in patients who are not candidates for surgery.
The type of radiation therapy used most often in treating pancreatic cancer is external-beam radiation therapy, which means the radiation is administered from a machine, and the procedure is a lot like having an x-ray.
A new type of radiation therapy — intraoperative electron-beam radiation therapy — is under investigation. In this approach, a special type of external-beam radiation therapy is used during surgery.The doctor can move surrounding organs out of the way of the radiation beam, allowing larger doses of radiation to be used without harming the nearby organs.
Chemotherapy, the use of cancer-killing drugs, can be administered systemically by injection into a vein (IV) or by mouth. In systemic chemotherapy, the anticancer drugs enter the bloodstream and travel throughout the whole body, attacking cancer cells found beyond the pancreas. Anticancer drugs are typically given in cycles (a period of treatment followed by a period of recovery, then another treatment period, etc.).The most common drugs used for pancreatic cancer are fluorouracil (5-FU) and gemcitabine. Ongoing studies are evaluating the effectiveness of combining these two chemotherapy drugs.
A new approach to treating cancer of the pancreas is hormone therapy. Both male and female sex hormones (androgens and estrogens) appear to affect the growth of pancreatic tissue. Some research suggests that tamoxifen, a hormonal therapy used to treat women with breast cancer, has been somewhat effective in treating pancreatic cancer. In addition, hormones produced by the stomach and intestines might also stimulate the growth of pancreatic tumors, and drugs designed to block the action of these hormones are being investigated.