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Pancreatic Cancer

Anatomical facts:

The pancreas is located behind the stomach deep in the abdomen. This small, flat organ contains two types of glands: endocrine and exocrine. Endocrine cells are arranged in small clusters called islets and produce the hormones insulin and glucagon, which regulate the level of glucose (sugar) in the blood. Endocrine cells account for only 5% of cells in the pancreas. The rest are exocrine cells which make “juices” that contain enzymes necessary for food digestion.

Pancreatic juice is delivered to the small intestine through a system of tiny tubes called ducts. The small ducts all lead to the pancreatic duct, which empties into the duodenum, the first
section of the small intestine. The intersection of the pancreatic duct, the common bile duct that comes from the liver, and the duodenum is called ampulla of Vater.

Pancreatic Cancer Facts

Only 15% to 20% of pancreatic cancer patients are diagnosed while the cancer is still confined to the pancreas and surgery is feasible. This is the reason why only a quarter of the 37,000 people in the United States who are diagnosed with this cancer every year are still alive a year after the diagnosis. Cancer of the pancreas is the fourth leading cause of cancer deaths, with
33,000 deaths per year.

Diagnosing Pancreatic Cancer

The reasons for the difficulty in diagnosing pancreatic cancer in the early stage are twofold: one is that tumors in this organ produce very vague symptoms, which are usually attributed to other digestive conditions. The other is because the pancreas is located deep inside the abdomen and surrounded by other organs that interfere with the ability to see or feel tumors
during a routine physical exam.

Several risk factors for pancreatic cancer have been identified. People who have diabetes or chronic pancreatitis are at increased risk. Smoking, obesity, and a diet high in meats and fat have been linked to the development of this cancer. Pancreatic cancer is more common among males, people over 60, people with a family history of pancreatic cancer, and African Americans.

Types of Pancreatic Cancers

Distinct types of cancer originate from the exocrine cells and the endocrine cells in the pancreas. Tumors that develop from exocrine cells are usually adenocarcinomas and are much more common than endocrine tumors. Many of the information sources about pancreatic cancer provide data relevant only to this tumor type. Tumors that arise from the endocrine cells of the pancreas, sometimes called islet cell tumors or neuroendocrine tumors are very different from exocrine tumors with regard to symptoms, diagnosis, treatment, and prognosis. A third type of cancer, called ampullary cancer, develops in the ampulla of Vater. The treatment
for ampullary is similar to that for exocrine pancreatic cancer.

Pancreatic cancer can be cured if found early and surgery is possible. If the tumor is located in the “head” region of the pancreas, surgeons perform the Whipple procedure, where they cut out the diseased section and hook the remainder up to the small intestine. Sometimes it is necessary to remove the entire pancreas along with other tissues and organs, such as the spleen, bile duct, gallbladder, part of the small intestine, and lymph nodes. This procedure is called a pancreatectomy. If the entire pancreas is removed, patients will need to take insulin and oral enzymes to help with digestion. Unfortunately, even after surgery, pancreatic cancer tends to recur. Radiation therapy and chemotherapy are often prescribed after surgery to try to  slow down the progression of the disease and decrease symptoms. In recent years, the chemotherapy drug gemcitabine (Gemzar) has been shown to extend remission periods and improve survival rates of patients with inoperable pancreatic tumors.

Treatment for pancreatic cancer

Treatment for pancreatic cancer takes into consideration the stage at which cancer is detected, site of cancer, age and health of the patient. The primary objective is to remove the cancer completely. If that is not possible, the doctor tries to restrict the growth and spread of cancer. For advanced stages, treatment is given only to relieve the symptoms for making the patient a little more comfortable.

Treatment options available for pancreatic cancer are the following:

  • Surgery
  • Chemotherapy
  • Radiotherapy
  • Targeted therapy

Surgery

Surgery can be recommended if the cancer in the pancreas has not spread to adjacent blood vessels or other organs. If the cancer is an aggressive type, like pancreatic adenocarcinoma, a radical surgery will be needed. The type of surgery can be classified on the basis of cancer’s location in the pancreas.

Types of surgery:

Surgery recommended for tumors in the head of pancreas:

Patients with pancreatic adenocarcinomas most often have cancer in the head of pancreas. When the pancreatic cancer has grown at the head of the pancreas, doctors perform a surgery called a Whipple surgery (pancreatoduodenectomy). The operation involves removing both the head of the pancreas and adjacent tissues – like the first part of the small intestine, gall bladder and some portion of bile duct. A portion of the stomach will also be removed if the cancer spreads to stomach. If a portion of the stomach is removed, then the operation is called a standard Whipple operation. If the stomach is preserved, then the operation is called pylorus preserving Whipple operation.

It is also important for the surgeons to know whether the tumor has spread to the blood vessels called superior mesenteric vein and artery, since they are close to the head of the pancreas. CT scan and endoscopic sonography before the surgery helps the doctor to find out specific details of the condition of the cancer and act accordingly. After removal of the affected regions, the doctor reconnects the remaining parts so that food eaten can be digested. There is a risk of bleeding and infection for this surgery. Recovery after this surgery takes a long time. The patient may be hospitalized for around 2 weeks. He should then take a rest for a long time at home. Adjuvant chemotherapy and radiation therapy in combination with the Whipple surgery for patients with pancreatic adenocarcinoma gives better results.

Surgery recommended for tumors in the tail and body of pancreas:

 When the pancreatic cancer is located at the tail of the pancreas the doctors perform a surgery called distal pancreatectomy. It involves removal of the tail of the pancreas and in some cases an additional small part of the body. The spleen may also be removed depending on the condition. Removing the spleen by surgery is called splenectomy. There is a risk of infection and bleeding after the surgery.

Cancers in the tail of the pancreas are more aggressive than those in the head. Most often they spread fast and are detected late. Surgery is usually not possible if the cancer has spread from the site of origin to other tissues or to a blood vessel called the celiac artery.

After the surgery patients should be treated with chemotherapy and radiation therapy.

Chemotherapy

Chemotherapy refers to administration of drugs orally or intravenously to treat cancer. A single drug or a combination of drugs can be used.

Chemotherapy is the preferred treatment for advanced stages of pancreatic cancer. Gemcitabine is a standard drug for pancreatic cancer. There are many other drugs available.

Chemotherapy may be given in combination with radiation therapy. Such a procedure is called chemoradiation. It shows better effect for cancers that have spread throughout the body.

Advanced stage of pancreatic cancer is usually treated by a combination of chemotherapy and targeted drug therapy. Gemcitabine is the chemotherapy drug most often recommended for advanced pancreatic cancer treatment.

Radiation therapy

Radiation therapy refers to the use of high-energy radiation to treat cancer. It is usually given to early stage pancreatic cancer patients. It can be of two types:

External radiation therapy: A beam of radiation from a machine outside the body is aimed at the affected site of the patient’s body.

Internal radiation therapy or brachytherapy: Radioactive substance sealed in small pellets is placed near the affected region. Cancer cells are killed by the radiations emitted from the radioactive substances.

The type of radiation therapy to be given to the patient is chosen by the radiation oncologist on the basis of stage and type of cancer. Radiation therapy may be used before or after surgery; alone or in combination with chemotherapy. Chemotherapy in combination with radiation therapy is called chemoradiation therapy. Chemoradiation is sometimes recommended as an adjuvant therapy for pancreatic cancer. 5-fluorouracil (5-FU)-based chemoradiation may be used for patients with localized pancreatic cancer.

Targeted therapy

Targeted therapy refers to the use of drugs that specifically kills only cancer cells without damaging normal cells. There are different types of targeted therapy for the treatment of pancreatic cancer.

Erlotinib (Tarceva), a targeted therapy drug, interferes with signalling pathways that stimulate the growth of cancer cells and help them to survive. The target of this drug is a protein called the Human Epidermal Growth Factor Receptor 1(HER 1 or EGFR). It can be used for advanced stage pancreatic cancer patients together with chemotherapy.

A number of targeted therapy drugs inhibit growth of new blood vessels that allow blood to carry nutrients and oxygen to the cancer cells. These are known as angiogenesis inhibitors. Some of these angiogenesis inhibitors like Bevacizumab (which targets VEGF-A) is under clinical trials. A number of targeted therapy drugs, like COX inhibitors, RAS inhibitors and telomerase inhibitors, are in clinical trials.

Pancreatic cancer vaccines

 Cancer vaccines are not like normal vaccines, which prevent a disease. Cancer vaccines can be used to treat cancer by stimulating the immune cells to identify and kill cancer cells. The use of these vaccines is still in early stages.

Clinical trials

Clinical trials refer to those kinds of treatment which are not yet standardized. It is a part of research that aims to develop better strategies for the treatment of cancer. The patients may willingly participate in clinical trials.

References

Wolfgang CL, Corl F, Johnson PT, Edil BH, Horton KM, Schulick RD, Fishman EK. Pancreatic surgery for the radiologist, 2011: an illustrated review of classic and newer surgical techniques for pancreatic tumor resection. AJR Am J Roentgenol. 2011 Dec; 197(6):1343-50.

Katz MH, Fleming JB, Lee JE, Pisters PW. Current status of adjuvant therapy for pancreatic cancer. Oncologist. 2010; 15(11):1205-13.

 

Additional Resources:

American Cancer Society. Learn about Pancreatic Cancer. Access at: www.cancer.org and select from the menu under “Choose a Cancer Topic.” Adetailed guide about pancreatic cancer can be printed as an Adobe Acrobat (.pdf) file.

National Cancer Institute. Pancreatic Cancer and Pancreatic Cancer: IsletCell. Access at: www.cancer.gov and click on “Types of Cancer.” The toppage of the sections links to patient versions of PDQ@ statements, clinicaltrial information, and other NCI publications on this topic.

People Living with Cancer. Pancreatic Cancer. Access at: www.plwc.organd click on “Cancer Type.” The PLWC oncologist-approved guide forpancreatic cancer can be printed in its entirety or by subtopic.

Pancreatic Cancer Action Network. Access at: www.pancan.org  One section of the site offers comprehensive information about pancreatic cancer including treatment option side effects, diet and nutrition, end of life, finding a health care professional, and clinical trials. The section for caregivers features tips and advice for the caregiver and for those helping the caregiver.

This article was originally published on 7/12/2014 and last revision and update of it was 9/14/2015.