About Pancreatic Cancer
Pancreatic cancer can develop from two kinds of cells in the pancreas: exocrine cells and neuroendocrine cells, such as islet cells. The exocrine type is more common and is usually found at an advanced stage. Pancreatic neuroendocrine tumors (islet cell tumors) are less common but have a better prognosis.
Pancreatic cancer starts when cells in the pancreas start to grow out of control. The pancreas is an organ that sits behind the stomach. It's shaped a bit like a fish with a wide head, a tapering body, and a narrow, pointed tail. The body of the pancreas is behind the stomach, and the tail of the pancreas is on the left side of the abdomen next to the spleen.
The pancreas has 2 main types of cells:
Most of the cells in the pancreas form the exocrine glands and ducts. The exocrine glands make pancreatic enzymes that are released into the intestines to help you digest foods (especially fats). The enzymes are first released into tiny tubes called ducts. These merge to form larger ducts, which empty into the pancreatic duct. The pancreatic duct merges with the common bile duct (the duct that carries bile from the liver), and empties into the duodenum (the first part of the small intestine) at the ampulla of Vater.
Endocrine cells make up a much smaller percentage of the cells in the pancreas. These cells are in small clusters called islets (or islets of Langerhans). These islets make important hormones like insulin and glucagon (which help control blood sugar levels), and release them directly into the blood.
The exocrine cells and endocrine cells of the pancreas form different types of tumors. It’s very important to know if the cancer in the pancreas is an exocrine or endocrine cancer. They have distinct risk factors and causes, have different signs and symptoms, are diagnosed with different tests, are treated in different ways and have different outlooks.
Pancreatic cancer is hard to catch early. It doesn't cause symptoms right away. When you do get symptoms, they are often vague or you may not notice them. They include yellowing of the skin and eyes, pain in the abdomen and back, weight loss and fatigue. Also, because the pancreas is hidden behind other organs, health care providers cannot see or feel the tumors during routine exams. Doctors use a physical exam, blood tests, imaging tests and a biopsy to diagnose it.
Several factors can affect a person’s chance of getting cancer of the pancreas. Most of these are risk factors for exocrine pancreatic cancer.
- Age: The risk of developing pancreatic cancer goes up as people age. Almost all patients are older than 45. About two-thirds are at least 65 years old. The average age at the time of diagnosis is 71.
- Chronic pancreatitis: Chronic pancreatitis, a long-term inflammation of the pancreas, is linked with an increased risk of pancreatic cancer (especially in smokers), but most people with pancreatitis never develop pancreatic cancer. Chronic pancreatitis is sometimes due to an inherited gene mutation. People with this inherited (familial) form of pancreatitis have a high lifetime risk of pancreatic cancer.
- Cirrhosis of the liver: Cirrhosis is a scarring of the liver. It develops in people with liver damage from things like hepatitis and heavy alcohol use. People with cirrhosis seem to have an increased risk of pancreatic cancer.
- Diabetes: Pancreatic cancer is more common in people with diabetes. The reason for this is not known. Most of the risk is found in people with type 2 diabetes. This type of diabetes most often starts in adulthood and is often related to being overweight or obese. It’s not clear if people with type 1 (juvenile) diabetes have a higher risk.
- Family history: Pancreatic cancer seems to run in some families. In some of these families, the high risk is due to an inherited syndrome. In other families, the gene causing the increased risk is not known. Although family history is a risk factor, most people who get pancreatic cancer do not have a family history of it.
- Gender: Men are slightly more likely to develop pancreatic cancer than women. This may be due, at least in part, to higher tobacco use in men, which raises pancreatic cancer risk.
- Inherited genetic syndromes: Inherited gene changes (mutations) can be passed from parent to child. These gene changes may cause as many as 10% of pancreatic cancers. Sometimes these changes result in syndromes that include increased risks of other cancers (or other health problems). Examples of genetic syndromes that can cause exocrine pancreatic cancer include:
- Hereditary breast and ovarian cancer syndrome, caused by mutations in the BRCA1 or BRCA2 genes
- Familial atypical multiple mole melanoma (FAMMM) syndrome, caused by mutations in the p16/CDKN2A gene
- Familial pancreatitis, usually caused by mutations in the PRSS1 gene
- Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), most often caused by a defect in the MLH1 or MSH2 genes
- Peutz-Jeghers syndrome, caused by defects in the STK11 gene. This syndrome is also linked with polyps in the digestive tract and several other cancers
- Von Hippel-Lindau syndrome, caused by mutations in the VHL gene. It 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 genetic syndromes, such as:
- Neurofibromatosis, type 1, which is caused by mutations in the NF1 gene. This syndrome leads to an increased risk of many tumors, including somatostatinomas
- Multiple endocrine neoplasia, type I (MEN1), caused by mutations in the MEN1 gene. This syndrome leads to an increased risk of tumors of the parathyroid gland, the pituitary gland, and the islet cells of the pancreas
- Overweight and obesity: Being overweight is a risk factor for pancreatic cancer. Very overweight (obese) people are about 20% more likely to develop pancreatic cancer.
- Race: African Americans are slightly more likely to develop pancreatic cancer than whites. The reasons for this aren’t clear, but it may be due in part to having higher rates of some other risk factors for pancreatic cancer, such as diabetes, smoking in men and being overweight in women.
- Stomach problems: Infection of the stomach with the ulcer-causing bacteria Helicobacter pylori (H. pylori) may increase the risk of getting pancreatic cancer.
- Tobacco use: Smoking is one of the most important risk factors for pancreatic cancer. The risk of getting pancreatic cancer is about twice as high among smokers compared to those who have never smoked. About 20% to 30% of pancreatic cancers are thought to be caused by cigarette smoking. Cigar and pipe smoking also increase risk, as does the use of smokeless tobacco products.
- Workplace exposure to certain chemicals: Heavy exposure at work to certain chemicals used in the dry cleaning and metal working industries may raise a person’s risk of pancreatic cancer.