Wednesday, April 20, 2011

Pancreatic Cancer Risk Factors: Overview

The causes and developing mechanism of pancreatic cancer are not fully understood by the modern medicine. However, certain personal, environmental, health, and inherited risk factors have been positively identified as potential causes for the higher chances of a person to develop the disease at some point of life.

Personal Risk Factors

Age: The risk of developing pancreatic cancer increases after age 50. Most patients are between the ages of 60 and 80 at the time of diagnosis.

Ethnicity: There is higher incidence of pancreatic cancer in Ashkenazi Jews, probably due to common genetic mutations present in at least 1% of individuals of this background. African Americans are also more likely to develop pancreatic cancer than are Asians, Hispanics, and Caucasians. The reasons for this discrepancy are not known but may be related to differences in other risk factors and habits like diet and cigarette smoking frequency.

Gender: Men have a greater risk of pancreatic cancer than women. This difference, though, is getting smaller over time in the United States. This may be related to cancer risk factors, like smoking, that are becoming more common in women.

Environmental Risk Factors

Cigarette Smoking: About 30% of pancreatic cancer cases are thought to be a direct result of cigarette smoking. People who smoke cigarettes are twice as likely to develop pancreatic cancer as people who do not smoke cigarettes. Additionally, the cancerous tumors that form as a result of cigarette smoking grow at an accelerated rate and develop approximately 10 years earlier than tumors not related to smoking.

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Diet: Diets high in meats, cholesterol fried foods and nitrosamines may increase the risk, while diets high in fruits and vegetables may reduce the risk of pancreatic cancer.

Chemicals Exposure: Long-term exposure to certain chemicals, such as gasoline and related compounds, as well as certain insecticides, may increase the risk of developing cancer of the pancreas.

Health Risk Factors

Chronic Pancreatitis: Pancreatitis is an inflammation of the pancreas. People diagnosed with chronic pancreatitis have an increased risk of developing pancreatic cancer. Chronic pancreatitis is a condition that can strike people of any age. It is typically diagnosed in people who are 35-45 years old. It can be due to a number of factors including hereditary (genetic) pancreatitis, malformation of pancreas ducts, trauma to pancreas, or excessive alcohol abuse for many years.

Hereditary Pancreatitis: Hereditary pancreatitis (HP) is a condition associated with recurrent pancreatitis (inflammation of the pancreas) and an increased risk of pancreatic cancer. 

Diabetes: Pancreatic cancer is two times more likely to occur in people who have diabetes than in people who do not have diabetes. However, the relationship between diabetes and pancreatic cancer is still not completely understood. It is not uncommon for individuals to develop diabetes before pancreatic cancer is detected and it may be that this glucose intolerance is actually caused by changes in the pancreas resulting from the cancer.

Cirrhosis: Pancreatic cancer is more common in patients who have a history of cirrhosis (a chronic liver disease).

Peptic ulcer surgery: Patients who have had a portion of their stomach removed (partial gastrectomy) appear to have an increased risk for developing pancreatic cancer.

Stomach problems: Infection of the stomach with the ulcer-causing bacteria Helicobacter pylori (H. pylori) may increase the risk of getting pancreatic cancer. Some researchers believe that excess stomach acid may also increase the risk.

Hepatitis B infection: Hepatitis viruses are viruses that infect the liver. One study has shown that a previous hepatitis B infection was twice as common in people with pancreatic cancer than in people without the cancer. However, more research is needed to learn more about this link.

Weight: The body mass index (BMI) is a statistical measure calculated based on a person's height and weight. A person with a BMI above 25 is considered overweight and this can increase the risk of developing pancreatic cancer.

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Height: Tall people have a higher risk of pancreatic cancer. Researchers don’t know exactly why, but it may be related to the fact that tall people grow more. Some of the same hormones and other factors that make people grow may also increase the chance that dividing cells become abnormal and turn cancerous.

Inherited Risk Factors

Inherited Risk: Up to 10% of pancreatic cancer is related to a family history of the disease. The risk of developing pancreatic cancer increases by 2-3 times if a person's mother, father, sibling, or child had pancreatic cancer. The risk multiplies if a greater number of family members are affected. There are several inherited gene mutations that have been linked to an increased risk of pancreatic cancer including the genes responsible for breast and ovarian cancer, and melanoma.  

Genetic Syndromes: Inherited gene mutations are abnormal copies of certain genes that can be passed from parent to child. These abnormal genes may cause as many as 10% of pancreatic cancers and can cause other problems as well. Examples of the genetic syndromes that can cause exocrine pancreatic cancer include:
  • Hereditary breast and ovarian cancer syndrome, caused by mutations in the gene BRCA2
  • Familial melanoma, caused by mutations in the gene p16
  • Familial pancreatitis, caused by mutations in the gene PRSS1
  • Hereditary non-polyposis colorectal cancer (HNPCC), most often caused by a defect in either the gene MLH1 or the gene MSH2. At least 5 other genes can also cause HNPCC: MLH3, MSH6, TGBR2, PMS1, and PMS2. This disorder is also known as Lynch syndrome.
  • Peutz-Jeghers syndrome (PJS), caused by defects in the gene STK1. This syndrome is also linked with polyps in the digestive tract and several other cancers
  • Von Hippel-Lindau syndrome, caused by mutations in the gene VHL, can lead to an increased risk of pancreatic cancer and carcinoma of the ampulla of Vater

Pancreatic neuroendocrine tumors and cancers can also be caused by a genetic syndrome, such as:
  • Neurofibromatosis, type 1, which is caused by mutations in the gene NF1. This syndrome leads to an increased risk of many tumors, including somatostatinomas.
  • Multiple endocrine neoplasia, type 1, caused by mutations in the gene MEN1, leads to an increased risk of tumors of the parathyroid gland, the pituitary gland, and the islet cells of the pancreas.

Sources and Additional Information:

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