Signs and symptoms of pancreatic cancer often don't occur until the disease is advanced. They may include:

• Pain in the upper abdomen that radiates to your back
• Loss of appetite or unintended weight loss
• Depression
• New-onset diabetes
• Blood clots
• Fatigue
• Yellowing of your skin and the whites of your eyes (jaundice)

It's not clear what causes pancreatic cancer in most cases. Doctors have identified factors, such as smoking, that increase your risk of developing the disease.

Understanding your pancreas

Your pancreas is about 6 inches (15 centimeters) long and looks something like a pear lying on its side. It releases (secretes) hormones, including insulin, to help your body process sugar in the foods you eat. And it produces digestive juices to help your body digest food.

How pancreatic cancer forms

Pancreatic cancer occurs when cells in your pancreas develop mutations in their DNA. These mutations cause cells to grow uncontrollably and to continue living after normal cells would die. These accumulating cells can form a tumor. Untreated pancreatic cancer spreads to nearby organs and blood vessels.

Most pancreatic cancer begins in the cells that line the ducts of the pancreas. This type of cancer is called pancreatic adenocarcinoma or pancreatic exocrine cancer. Rarely, cancer can form in the hormone-producing cells or the neuroendocrine cells of the pancreas. These types of cancer are called islet cell tumors, pancreatic endocrine cancer and pancreatic neuroendocrine tumors.

Factors that may increase your risk of pancreatic cancer include:

• Chronic inflammation of the pancreas (pancreatitis)
• Diabetes
• Family history of genetic syndromes that can increase cancer risk, including a BRCA2 gene mutation, Lynch syndrome and familial atypical mole-malignant melanoma (FAMMM) syndrome
• Family history of pancreatic cancer
• Smoking
• Obesity
• Older age, as most people are diagnosed after age 65

A large study demonstrated that the combination of smoking, long-standing diabetes and a poor diet increases the risk of pancreatic cancer beyond the risk of any one of these factors alone.

As pancreatic cancer progresses, it can cause complications such as:

• Weight loss. A number of factors may cause weight loss in people with pancreatic cancer. The cancer itself may cause weight loss. Nausea and vomiting caused by cancer treatments or a tumor pressing on your stomach may make it difficult to eat. Or your body may have difficulty processing nutrients from food because your pancreas isn't making enough digestive juices.

Your doctor may recommend pancreatic enzyme supplements to aid in digestion. Try to maintain your weight by adding extra calories where you can and making mealtime as pleasant and relaxed as possible.

• Jaundice. Pancreatic cancer that blocks the liver's bile duct can cause jaundice. Signs include yellow skin and eyes, dark-colored urine, and pale-colored stools. Jaundice usually occurs without abdominal pain.

Your doctor may recommend that a plastic or metal tube (stent) be placed inside the bile duct to hold it open. This is done with the help of a procedure called endoscopic retrograde cholangiopancreatography (ERCP). During ERCP an endoscope is passed down your throat, through your stomach and into the upper part of your small intestine. A dye is then injected into the pancreatic and bile ducts through a small hollow tube (catheter) that's passed through the endoscope. Finally, images are taken of the ducts.

• Pain. A growing tumor may press on nerves in your abdomen, causing pain that can become severe. Pain medications can help you feel more comfortable. Radiation therapy might help stop tumor growth temporarily to give you some relief.

In severe cases, your doctor might recommend a procedure to inject alcohol into the nerves that control pain in your abdomen (celiac plexus block). This procedure stops the nerves from sending pain signals to your brain.

• Bowel obstruction. Pancreatic cancer that grows into or presses on the first part of the small intestine (duodenum) can block the flow of digested food from your stomach into your intestines.

Your doctor may recommend a tube (stent) be placed in your small intestine to hold it open. Or surgery may be necessary to attach your stomach to a lower point in your intestines that isn't blocked by cancer.