Pancreatic Cancer

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Pancreatic cancer

Definition

The pancreas is a gland found in the abdomen behind the stomach. The pancreas secretes a fluid that breaks down fats and proteins, and releases hormones, such as insulin, to control blood sugar levels. Pancreatic cancer is uncontrolled growth of cells of the pancreas. A higher than average number of pancreatic cancer cases occurring in the same family is known as familial pancreatic cancer.

Description

Most pancreatic cancer grows from cells from the exocrine pancreas, the secreting portion of the pancreas. The most common appearance of pancreatic cancer cells is gland-like, which is termed adenocarcinoma.

In most cases, it is difficult to determine the cause of pancreatic cancer. Both environmental as well as genetic risk factors have been suggested for pancreatic cancer. A high-fat diet has been linked to increased pancreatic cancer risk, whereas diets high in vegetables and fruits seem to lower the risk. Smoking is known to increase the risk of pancreatic cancer; it is estimated that as many as 30% of pancreatic cancer cases are linked to smoking. Alcohol use and coffee consumption have been linked with increased pancreatic cancer risk, in some studies, but this connection has not been proven. Previous stomach surgery also may increase the risk of pancreatic cancer. Aflatoxin, a common fungal contaminant of certain foods, such as rice, corn, and peanuts, is a known cause of liver cancer, and has been postulated to also pose a risk for pancreatic cancer. However, no link has been found.

Certain occupations, such as farming or manufacturing, may increase the risk of pancreatic cancer. Multiple studies have shown that exposure to pesticides increases the risk of pancreatic cancer. The relationship of diabetes to pancreatic cancer has been closely studied. It is uncertain whether diabetes is the cause or the symptom of pancreatic cancer. Presence of diabetes, however, may alert health care providers to the presence of pancreatic cancer. Long-term inflammation of the pancreas, chronic pancreatitis, may increase the risk of pancreatic cancer as well. Genetic risk factors have also been reported.

Genetic profile

Several studies have reported a higher rate of pancreatic cancer in relatives of individuals with the disease. Hereditary causes are estimated to account for about 10% of all pancreatic cancer cases. The most well-known case of familial pancreatic cancer is that of former president Jimmy Carter, whose mother, sister, and brother all died of the disease. Some risk is thought to be due to known hereditary conditions, whereas, in other cases, a known genetic syndrome has not been determined.

There are several known genetic syndromes that increase the risk of pancreatic cancer. Alterations in the gene, BRCA2, have been clearly linked to increases in breast and ovarian cancer, as well as a potential increased pancreatic cancer risk. Hereditary pancreatitis, which is due to alterations in the cationic trypsinogen gene on chromosome 7 at 7q35, causes long-term, recurrent inflammation of the pancreas. Individuals with hereditary pancreatitis are estimated to have a 40% risk of pancreatic cancer by age 70. Changes, or mutations, in the CDKN2A (p16) gene can increase risks of melanoma, a type of skin cancer and, possibly, pancreatic cancer. Hereditary non-polyposis colon cancer (HNPCC), or Lynch syndrome, increases the risk of colon cancer and other cancers, including pancreatic

cancer, in some families. Peutz-Jeghers (familial adenomatous polyposis, FAP) and Li-Fraumeni syndrome s cause slightly increased risks of pancreatic cancer, in addition to the other symptoms of the disorders. All of these disorders are inherited in an autosomal dominant pattern. With autosomal dominant inheritance, men and women are equally likely to inherit the syndrome, and children of affected individuals are at 50% risk of inheriting the gene alteration.

Other syndromes, some with different inheritance patterns, may be linked to pancreatic cancer as well. Genetic testing is available for many of these known syndromes, but due to the complexity of the disorders, genetic counseling should be considered before testing.

Some families with increased pancreatic cancer rates do not have a known genetic syndrome as the cause. It is possible that environmental factors or chance could explain some cases of pancreatic cancer in families; however, it is also possible that other as yet unknown genetic causes could explain some cases of familial pancreatic cancer. While genetic testing may not be available in all cases, families may participate in collections, or registries, of familial pancreatic cancer cases for research purposes.

Demographics

Pancreatic cancer is the fifth leading cause of cancer-related death for both men and women in the United States. Pancreatic cancer is more common in industrialized countries, with African Americans in the United States having one of the highest rates. The rate of pancreatic cancer increases with age, with most patients diagnosed between the ages of 60 and 80. Pancreatic cancer is more common in men than in women.

Signs and symptoms

Since the symptoms of pancreatic cancer are not specific to the disease, and typically do not develop until the cancer has progressed, it is difficult to diagnosis pancreatic cancer at an early stage.

The symptoms of pancreatic cancer can include:

weight loss
loss of appetite
abdominal or back pain
jaundice (yellow color to skin and eyes)
digestive problems, including greasy stool
sudden diabetes

Diagnosis

If pancreatic cancer is suspected, regardless of the cause, a physical exam often is done first, and certain body imaging tests may be recommended. One imaging test that may be done is a computed tomography (CT) scan. This exam creates pictures of the interior of the body from computer-analyzed differences in x rays passing through the body. Evidence of substantial tumors or any metastasis (spreading of cancer) can be detected by CT scanning. Once a biopsy is taken, the tissue sample is examined by CT for evidence of cancer and this typically determines the diagnosis.

Ultrasound is another method of viewing internal body structures. In ultrasound, sound waves are passed into the body and a computer develops an image based on the returned sound waves. Ultrasound is generally less expensive and more easily available than CT; however, there are limitations to the use of ultrasound in viewing the pancreas. Ultrasound may be used in addition

to CT. Endoscopic retrograde cholangiopancreatography (ERCP) is a method of viewing the pancreas by inserting a thin tube down the throat, injecting of dye into the pancreatic and bile ducts, and taking x rays.

Once the tumor and any metastasis has been identified and the biopsy tissue evaluation has been done, the tumor can be staged. Staging is a ranking system that provides a method of describing the extent and characteristics of a cancer. Staging can be used to help determine the treatment and prognosis for a given cancer.

Treatment and management

Surgery often provides the best chance of a cure, though it is not often possible due to the spread of cancer. Removal of all or part of the pancreas and other areas, such as the duodenum (the first part of the small intestine), is known as the Whipple procedure. Complications of this surgery include infection and bleeding.

Chemotherapy is cancer-killing medicine that has been found to increase survival in some patients. This drug can be given intravenously or orally. Once in the bloodstream, chemotherapy agents reach other parts of the body. There are different chemotherapy agents and the side effects may be different as well, including nausea, hair loss, low blood counts, and other effects.

Recent improvements in radiation, high-energy rays directed at cancer cells, have made this therapy more effective. Although cures due to radiation therapy are uncommon, relief from pain and increased survival are possible. Side effects of radiation therapy may include skin changes, upset stomach, and other effects.

Sometimes, surgery, radiation, or other therapies are done to relieve symptoms rather than cure the cancer. This is known as palliative treatment.

Involvement in research as part of clinical trials may be offered to certain patients. Although treatments through clinical trials may not be proven, it is an opportunity to potentially benefit from new therapies.

Screening before cancer development may be considered for patients with a higher risk of the disease either due to a known genetic syndrome or to a family history of pancreatic cancer. ERCP and ultrasound have been used for screening purposes; however, the usefulness and cost-effectiveness of these tests for screening needs further evaluation. Surveillance may be considered for persons with two or more close relatives (first-degree family members) with pancreatic cancer, or with one close relative (first-degree) with pancreatic cancer at an early age (before age 50), or with two or more distant relatives (second-degree), one of which was affected before age 50.

Prophylactic pancreatectomy, surgical removal of the pancreas before any cancer development, has been considered in cases with a hereditary risk. The concern with prophylactic pancreatectomy is that there is a risk of serious complications, and consequently the decision must be weighed carefully.

Prognosis

It is difficult to diagnose pancreatic cancer early and, therefore, the cancer frequently has spread to other locations in the body, such as the liver or lymph nodes (part of the immune system). Survival rates five years after pancreatic cancer, in general, have been reported to be between 3% and 25%. Most long-term survivors originally had smaller tumors and no spreading of the cancer. Of course, every case of pancreatic cancer is different, and it is difficult to predict the course and survival for each individual patient. The prognosis of individuals with hereditary risk factors is dependent on the syndrome, if any, and the aggressiveness of the particular cancer.

Resources

BOOKS

Flanders, Tamar, et al. "Cancers of the Digestive System." In Inherited Susceptibility to Cancer: Clinical, Predictive and Ethical Perspectives, edited by William D. Foulkes and Shirley V. Hodgson. Cambridge: Cambridge University Press, 1998.

Redlich, Philip, et al. "Tumors of the Pancreas, Gallbladder and Bile Ducts." In Clinical Oncology, edited by Raymond E. Lenhard, Jr., et al. Atlanta, GA: American Cancer Society, 2001.

PERIODICALS

Beard, John, Tim Sladden, Geoffrey Morgan, Geoffrey Berry, Lyndon Brooks, and Anthony McMichael. "Health Impacts of Pesticide Exposure in a Cohort of Outdoor Workers." Environmental Health Perspectives 111, no. 5 (May 2003): 724–730.

Clary, T., and B. Ritz. "Pancreatic Cancer Mortality and Organochlorine Pesticide Exposure in California, 1989–1996." American Journal of Industrial Medicine 43 (2003): 306–313.

William, J. H., T. D. Phillips, P. E. Jolly, J. K. Stiles, C. M. Jolly, and D. Aggarwal. "Human Aflatoxicosis in Developing Countries: A Review of Toxicology, Exposure, Potential Health Consequences, and Interventions." American Journal Clinical Nutrition 80 (2004): 1106–1122.

ORGANIZATIONS

American Cancer Society. 1599 Clifton Rd. NE, Atlanta, GA 30329. (800) 227-2345. (April 22, 2005.) <http://www.cancer.org>.

National Cancer Institute. Office of Communications, 31 Center Dr. MSC 2580, Bldg. 1 Room 10A16, Bethesda, MD 20892-2580. (800) 422-6237. (April 22, 2005.) <http://www.nci.nih.gov>.

National Familial Pancreas Tumor Registry. Johns Hopkins Hospital, Weinberg Building, Room 2242, 401 North Broadway, Baltimore, MD 21231-2410. (410) 955-9132. (April 22, 2005.) <http://www.path.jhu.edu/pancreas>.