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What is Pancreatic Cancer?
THE PANCREAS | Cancer of the Pancreas | Types | Precursors
The pancreas is an organ of the digestive system located deep in the upper part of the abdomen, behind the stomach and in front of the
spine (Figure 1-1). It is only about 2 inches wide and 6 to 8 inches long and sits horizontally across the abdomen (Figure 1-2). The pancreas is composed of three parts.
The large, rounded end is called the head. It is located on the right side of the abdomen and near the beginning of the small intestine, which is called the duodenum. The middle section, called the body, is tucked behind the stomach. The thin end of the pancreas, called the tail, is located on the left side of the abdomen next to the spleen. 1-3
Two separate types of glandular tissue make up the bulk of the pancreas, exocrine and endocrine tissue. The exocrine tissue
comprises 95 percent of the pancreas and acts as an exocrine gland. The endocrine tissue makes up the remaining 5 percent of the pancreas and acts as an endocrine gland. 3
Exocrine glandular tissue produces pancreatic enzymes to aid in the digestion of food. These enzymes are made in cells (called acinar cells) in the exocrine tissue. The pancreatic enzymes flow down a tube called the pancreatic duct, which is the main duct of the pancreas. This duct runs along the entire length of the pancreas and merges with the bile duct. From the pancreatic duct, the enzymes enter the duodenum. Bile from the liver flows down the bile duct and also empties
into the duodenum. All of these fluids help the body digest food.
The endocrine glandular tissue of the pancreas produces hormones and releases them into the bloodstream. The hormones are
made in collections of cells called the Islets of Langerhans, which are found in small clusters throughout the pancreas. Insulin is an important hormone made in these cells and helps control blood sugar levels. 3
CANCER OF THE PANCREAS
The word cancer is used to describe any one of a group of diseases in which the cells are abnormal, grow out of control, and can spread.
These abnormal cells are different from normal cells in both appearance and function. Pancreatic cancer occurs when abnormal
cells grow out of control in the tissue of the pancreas and form a tumor. 1,2
Because the pancreas lies deep in the abdomen, a doctor performing an examination on a patient would not be able to feel a
pancreatic tumor. Pancreatic cancer has no early warning signs, and there are no effective screening tests. As a result, pancreatic
cancer rarely is discovered early. Many times the diagnosis is not made until the cancer has spread to other areas of the
body. 3
Unfortunately, symptoms of pancreatic cancer often do not appear until the tumor has grown large enough to interfere with
the function of nearby organs or exert pressure on the spine.
When early symptoms do occur, they are often vague and nonspecific. All of these symptoms can be caused by medical conditions
other than pancreatic cancer. Possible early symptoms that should be evaluated by your physician are:
- pain in the upper or middle abdomen
- nausea
- weight loss
- anorexia (a diminished appetite)
- jaundice (a yellowing of the skin or whites of the eyes and stool discoloration), often with general itchiness (pruritis)
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In the United States, cancer of the pancreas is the fourth leading cause of cancer deaths in both men and women. 4 In 2007, about 37,000 patients will be diagnosed with pancreatic cancer. 5 Almost all patients with pancreatic cancer are older than 55 years (90 percent), and more than 70 percent are older than
65 years. 3 Unfortunately, pancreatic cancer can also occur in younger people, especially those who have a family history of the disease.
Today, better diagnostic tests and newer treatments are beginning to change these statistics and provide a more optimistic
future for patients diagnosed with pancreatic cancer.
TYPES OF PANCREATIC CANCER
The most common types of pancreatic cancers are exocrine tumors called ductal adenocarcinomas, which are thought to form in the pancreatic ducts. About two thirds of all pancreatic cancers form in the head of the pancreas.
The other third form in the body and tail. 3 These tumors are malignant, meaning they can invade nearby tissues and organs. Cancerous cells can also spread through the blood and lymphatic system to other parts of the body. When this occurs, it is called metastatic cancer and it may be life-threatening.
Tumors can also form in the endocrine cells of the pancreas. These types of rare tumors are called islet cell tumors or pancreatic
endocrine neoplasms, and most often they are benign. Those that are malignant are called islet cell cancers or malignant pancreatic endocrine neoplasms. Other rare forms of
pancreatic cancer are listed in Box 1-1. It is important to distinguish between exocrine and endocrine tumors because each has different signs and symptoms, are
diagnosed using different tests, have different treatments, and have different prognoses. 3 This handbook does not focus on endocrine tumors or other rare tumors of the pancreas and related organs. However, most National
Cancer Institute–Designated Comprehensive Cancer Centers have experts who can help patients who have these rare pancreatic
tumors.
| Box 1-1 |
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RARE FORMS OF PANCREATIC CANCER 6
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Endocrine tumors
Gastrinomas
Glucagonomas
Insulinomas
Somatostatinomas
VIPomas
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Cystic tumors
Mucinous cystic neoplasms
Serous cystic neoplasms
Solid pseudopapillary tumors
Cystic islet cell tumors
Intraductal papillary mucinous neoplasms (IPMNs)
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Acinar cell cancer
Variants of ductal adenocarcinoma, such as
Adenosquamous carcinoma
Colloid carcinoma
Hepatoid carcinoma
Medullary carcinoma
Signet ring cell carcinoma
Undifferentiated carcinoma
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Pancreatic lymphoma
Metastases to the pancreas from a cancer arising in another organ
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Until recently, little was known about cancer of the pancreas. Because of new discoveries in all types of cancer, more research
is being focused on pancreatic cancer. Scientists are beginning to understand the genetic basis of this disease. (See Question 2 on Causes.) This knowledge may help in understanding its causes and in determining who is most at risk. Eventually, new and better
ways to treat pancreatic cancer will be discovered.
PRECURSORS TO PANCREATIC CANCER
Intraductal papillary mucinous neoplasms (IPMNs) have been recognized as a special type of abnormal tumors in the pancreas. These tumors are called “mucinous” because they
produce large amounts of mucus, which clogs and enlarges the pancreatic duct. IPMNs are very different from most pancreatic
tumors. They may be present for a long time without spreading, and patients with some types of IPMNs have a good chance of
a cure with surgery. Because IPMNs also have very distinct features, researchers believe that studying them and their genetic
makeup may lead to new ways of diagnosing more typical forms of pancreatic cancer. 7
Pancreatic intraepithelial neoplasia (PanIN) are lesions too small to see with the naked eye. Like IPMNs, PanIN lesions can also progress to invasive pancreatic cancer
over time.
REFERENCES ! Click reference number to return to text.
1. National Cancer Institute. Pancreatic cancer. www.cancer.gov/cancertopics/ types/pancreatic. Accessed April 1, 2007.
2. National Cancer Institute. Pancreatic cancer. www.cancer.gov/cancertopics/ wyntk/pancreas. Accessed April 13, 2007.
3. American Cancer Society. What is cancer of the pancreas? www.cancer.org. Accessed April 1, 2007.
4. Journal of the American Medical Association. Pancreatic cancer. JAMA. 2007;297:330.
5. National Cancer Institute. Pancreatic cancer (PDQ®): treatment. Health professional version. March 15, 2007. www.cancer.gov/cancertopics/pdq/
treatment/pancreatic/healthprofessional. Accessed April 19, 2007.
6. Mulkeen AL, Yoo PS, Cha C. Less common neoplasms of the pancreas. World J Gastroenterol. 2006;12:3180-5.
7. Sohn TA, Yeo CJ, Cameron JL, et al. Intraductal papillary mucinous neoplasms of the pancreas: an increasingly recognized
clinicopathologic entity. Ann Surg. 2001;234:313-21.
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