Pancreatic cancer is a disease in which malignant (cancer) cells form in the tissues of the pancreas.
The pancreas is a gland about 6 inches long that is shaped like a thin pear lying on its side. The wider end of the pancreas is called the head, the middle section is called the body, and the narrow end is called the tail. The pancreas lies behind the stomach and in front of the spine.
The pancreas has two main jobs in the body:
- To produce juices that help digest (break down) food.
- To produce hormones, such as insulin and glucagon, that help control blood sugar levels. Both of these hormones help the body use and store the energy it gets from food.
The digestive juices are produced by exocrine pancreas cells and the hormones are produced by endocrine pancreas cells. About 95% of pancreatic cancers begin in exocrine cells.
The most common type of cancer of the pancreas is an adenocarcinoma of the pancreas (approximately 90 to 95%). Although it is the 4th leading cause of cancer deaths in men and women in the United States, survival is getting better everyday. Almost 30 to 40% of the patients have disease confined to the pancreas. It is important to find an experienced surgeon who can completely resect (remove) the cancer. There is growing evidence to suggest that post-op chemotherapy with or without radiotherapy improves long term survival and is slowly becoming the norm.
In over half of patients, the disease has sometimes grown beyond the pancreas. There two subtypes. One is locally advanced, i.e. involving the superior mesenteric vein or superior mesenteric artery. The second is the presence of metastatic disease, i.e. disease spread beyond the pancreas. Involvement of the portal vein or superior mesenteric vein does not always preclude surgery. So if your surgeon turns you down, a second opinion is in order. On the other hand, involvement of the superior mesenteric artery is a relative contraindication. However with slow growing tumors such neuroendocrine tumors, it may be reasonable to consider resecting this and reconstructing the artery with a graft.
Neuroendocrine tumor(s) of the pancreas
Cells that have both a neural component (receive messages via a nerve) and an endocrine component (respond by releasing a hormone) are called neuroendocrine cells. The pancreas and a few other organs have a relative abundance of neuroendocrine cells.
Less than 5% of pancreatic tumors are of neuroendocrine origin. There are two distinct types:
- Pancreatic endocrine tumors (also know as endocrine tumors of the pancreas) or islet cell tumors of the pancreas.
- Carcinoid tumors. These tumors have a completely different diagnostic and therapeutic profile, and generally have a more favorable prognosis.
There are several subtypes of islet cells. The most common type is alpha cells producing glucagon (15% of total islet cells), beta cells producing insulin and amylin (75%), delta cells producing somatostatin (3 to 5%), PP cells producing pancreatic polypeptide (3 to 5%), epsilon cells producing ghrelin (<1%). Islet cell tumors can be functional (as in secrete excess hormones in to the body) or non-functional (do not secrete hormones).
Carcinoid tumors are cancerous, except they are slow growing. This tumor is often associated with an increased production of serotonin (5-HT), a chemical transmitter that causes a specific set of symptoms including flushing, diarrhea, weight loss, heart palpitations etc. This set of symptoms is called “carcinoid syndrome.” Carcinoid tumors can also arise in lung, thymus, stomach, duodenum, small bowel, colon and rectum. Less than one percent of carcinoid tumors originate in the pancreas.
True cysts of the pancreas
True cysts are very rare and are defined pockets of fluid collection around the pancreas that are lined by epithelium. They are not the most common type of cysts of the pancreas. Pseudocyst or “false” cysts of the pancreas are lined by granulation tissue and often occur as sequelae of acute or chronic pancreatitis. These cysts often contain a mixture of pancreatic juices mixed with old blood that had leaked out from the ruptured or inflamed pancreas.
The most common forms of true cycts are mucinous and serous cystadenomas. The other infrequent cystic tumors include papillary cystic tumors, cystic neuroendocrine tumor, cystic teratoma, lymphangioma, hemangioma, and paraganglioma.
Mucinous type are the most common cystic pancreatic neoplasms and are often seen in women over the age of 60. Abdominal pain, weight loss, early satiety, nausea and vomiting are among the most frequently reported symptoms. But most are asymptomatic and are discovered incidentally during a routine check up when a scan is ordered. While some may be benign, a good percentage of these may be premalignant or malignant and therefore need thorough evaluation.
At the City of Hope, our team of surgeons work closely with the gastroenterologists to devise an individualized plan based on the CT or MRI scan and the ERCP with an EUS. Cystic fluid is usually aspirated when possible and an analysis of the fluid to rule out malignant potential is done in the laboratory.