Pancreatic Cancer Health Article

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 syndromes 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.