Pancreatic cancer refers to carcinoma that develops in the cells of the pancreas. It is ranked as the 12th most common cancer and is responsible for 7% of all cancer-related deaths in both men and women. As the patients seldom exhibit specific signs and symptoms until the advanced stage of the disease, it ranks as the 7th highest cause of cancer mortality in the world. The global prevalence rate of pancreatic cancer is 1 per 100, 000 people per year.
About pancreatic cancer
The pancreas is a long, flat gland located in the abdomen behind the stomach. It plays a crucial role in the digestive as well as endocrine system. Generally, there are two kinds of cells in the pancreas– exocrine cells and neuroendocrine cells. Exocrine cells produce digestive enzymes while the neuroendocrine cells produce several hormones, including insulin and glucagon.
Pancreatic cancers arise when cells in the pancreas begin to grow and divide at an uncontrollable rate and form a mass called tumor. Tumors can be benign (do not invade nearby tissues) or malignant (spread to other parts of the body).
Types of pancreatic cancer
As the pancreas is made of endocrine and exocrine cells, each type of these cells can give rise to a different type of tumor.
- Exocrine tumors, the most common type of pancreatic cancer, develop from the cells that line the ducts which deliver enzymes to the small intestine (exocrine cells). About 95% of cancers of the exocrine pancreas are adenocarcinomas.
- Neuroendocrine tumors are less common pancreatic cancer that arises from the endocrine cells. They often grow slower than the exocrine tumors and account for about 7% of all pancreatic tumors.
Signs and symptoms of pancreatic cancer
Pancreatic cancers often do not cause any signs or symptoms until it reaches the advanced stages of the disease.
Possible symptoms of pancreatic cancer include:
- Jaundice (yellowing of the skin, eyes or both) with or without itching
- Pain, usually in the abdomen or back
- Weight loss
- Loss of appetite
- Changes in stool
- Pancreatitis (swelling of the pancreas)
- Recent-onset diabetes
- Abdominal swelling
Causes/ Risk Factors
The exact cause of pancreatic cancer is not certain, but the following factors may increase the risk of pancreatic cancer:
Modifiable risk factors:
- Being overweight
- A diet high in red and processed meats
- Exposure to certain chemicals like chlorinated hydrocarbons and polycyclic aromatic hydrocarbons
- Long term heavy alcohol consumption
Non-modifiable risk factors:
- Age over 60 years
- Male gender
- Personal history of diabetes or chronic pancreatitis (inflammation of the pancreas)
- Family history of pancreatic cancer or pancreatitis
- Cirrhosis or scarring of the liver
- Stomach infection with the ulcer-causing bacteria, Helicobacter pylori (H. pylori)
- Gingivitis or periodontal disease
Pancreatic cancer is difficult to detect and diagnose as there may not be any noticeable signs or symptoms. If a person is suspected of pancreatic cancer, the following tests are recommended for an accurate diagnosis:
- Imaging tests: Tests such as computerized tomography (CT) scan, ultrasound, MRI, and PET scan are done to examine the suspicious area to learn how far the cancer may have spread. Tests like angiography and cholangiopancreatography are performed to visualize the blood vessels and pancreatic ducts, respectively.
- Blood test: Blood tests help to detect proteins known as tumor markers secreted by pancreatic cancer cells
- Liver function tests: These tests check for abnormal levels of bilirubin and other substances and determine the exact cause of jaundice.
- Tumor marker test: Tumor markers are proteins that are secreted by cancer cells, whose presence in blood indicates cancer. Tumor markers that may indicate pancreatic cancer are CA 19-9 and carcinoembryonic antigen (CEA).
- Complete blood count (CBC): This test will evaluate the general health condition of the patients.
- Biopsy: Biopsy involves inserting a specialized needle device guided radio-imaging to remove a small amount of tumor tissue for detailed examination. There are mainly three types of biopsy based on the mode of insertion of the needle: percutaneous (through the skin) biopsy, endoscopic biopsy, and surgical biopsy.
Stages of pancreatic cancer
The cancer staging is done using the TNM staging system. It provides detailed information about:
- Tumour (T): Whether the primary tumour has grown through the pancreas
- Node (N): Whether the cancer has spread to the surrounding lymph nodes
- Metastasis (M): Whether the cancer has spread to distant parts of the body
Based on the TNM staging, pancreatic cancer can be in any of the following stages:
- Stage 0a/0is: Cancer cells are located on the surface of the pancreatic duct cells.
- Stage I: Cancers are confined to the pancreas and are less than 4 cm in diameter.
- Stage II: Cancer cells have either spread beyond the pancreas and have not spread to lymph nodes, or are confined to the pancreas but have spread to lymph nodes.
- Stage III: Cancer cells have spread beyond the pancreas and involve either the celiac artery or superior mesenteric artery and/or the cancer has spread to nearby lymph nodes.
- Stage IV: Cancer has spread from the pancreas to distant parts of the body like bone, lung, liver or bones.
If you have been diagnosed with pancreatic cancer, your cancer care team will discuss your treatment options and its possible risk and benefits.
Treatment modalities available for pancreatic cancer are:
Surgery: Surgery is an appropriate treatment option for all pancreatic cancers as it completely removes the cancer cells and also increases the chances of long-term survival. A laparoscopy is recommended before the surgery to help determine the extent of the cancer and to check whether it can be surgically removed.
Surgical procedures to remove tumor include:
- Whipple procedure: During this procedure, the head of the pancreas and sometimes, the nearby structures like part of the gallbladder, stomach, small intestine, and the bile duct, are removed. Part of the body and the tail of the pancreas are left behind to produce digestive juices and hormones.
- Total pancreatectomy: This procedure involves the removal of the entire pancreas, as well as the gallbladder, part of the stomach and small intestine, and the spleen. It is recommended for end stage cancers. Patients who undergo this surgery must take hormonal and pancreatic enzyme supplements to maintain safe blood sugar levels and promote proper digestion.
- Distal pancreatectomy: In this surgery, the body and the tail of the pancreas is removed; spleen may be removed if the cancer has spread to the spleen.
If the cancer is in advanced stages and cannot be removed, the following types of palliative (to improve quality of life) surgery may be recommended:
- Biliary bypass: Here, the gallbladder or bile duct is removed if the cancer is blocking the bile duct or the bile is building up in the gallbladder.
- Endoscopic stent placement: In this surgery a stent (a thin tube) is placed to drain the bile, when the tumor is blocking the bile duct.
- Gastric bypass: If the tumor is blocking the flow of food from the stomach, the stomach can be sewn directly to the small intestine so the patient can continue to eat normally.
Radiation therapy: It involves using high energy beams like X-rays, gamma rays, and electron beams to shrink and destroy tumors. For pancreatic cancers, the radiation therapy can be scheduled after the surgical procedures to manage advanced stage cancer and to prevent the recurrence of cancer. Radiation therapy can be given externally through an external machine or it can be delivered internally by placing a radiation source near the site of tumor.
The side effects of radiation therapy may include mild skin reactions, fatigue, loss of appetite, nausea and vomiting, diarrhea, and weight loss.
Chemotherapy: It involves the use of drugs to kill or stop the growth of cancer cells. The drugs are usually taken orally or injected into the vein or muscles. For pancreatic cancers, chemotherapy is given with radiation therapy or after surgical procedures to enhance its effect.
Possible side effects of chemotherapy include nausea and vomiting, loss of appetite, hair loss, mouth sores and diarrhea or constipation.
Targeted therapy: It involves the use of specific drugs to identify and destroy the specific cancer cells without harming the normal cells. The targeted drugs work differently from standard chemo drugs and offer minimal side effects.
Immunotherapy: Immunotherapy involves the use of substances derived from living organisms, which either recognize or attack cancer cells or boost the natural defense of the immune system. Immunotherapy can be used to treat pancreatic cancer is called checkpoint inhibitors.
Palliative care: It involves specialized medical care that focuses on providing relief from pain using pain medications and other physical symptoms, such as digestive issues, nutritional deficiencies, etc. which occur particularly in the advanced stages of cancer. It also offers emotional support for stress, anxiety, and depression.
There is no definite way to prevent pancreatic cancer. However, some lifestyle changes and maintaining a general well-being may reduce your risk. It includes:
- quitting smoking
- keeping a healthy weight
- exercising regularly
- reducing alcohol consumption
Pancreatic cancer is difficult to diagnose as it often fails to show symptoms until the advanced stages. Compared with many other cancers, the five-year survival rate for pancreatic cancer is very low at just 5-10%. Despite the overall poor prognosis, an early diagnosis and prompt treatment can ensure better patient outcome.
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