What is pancreatic cancer ?
The cells of the pancreas sometimes undergo changes that make their growth and behavior abnormal.
TO REMIND YOU
The pancreas is a pear-shaped organ that measures on average 15 to 25 cm in length. Its widest part, called the head , is about 6 cm. Its central part is called the body, and its narrowest part, called the tail , is about 2 cm. It is located in the abdominal cavity behind the stomach.
The pancreas is a gland , meaning it is an organ that produces certain substances released into the blood ( endocrine gland ) or outside the body at the skin, digestive tract, or respiratory pathways ( exocrine gland ).
The pancreas is both an endocrine and exocrine gland that produces hormones essential for the proper functioning of the body, as well as enzymes necessary for food digestion.
The pancreas has a series of small ducts that lead into the pancreatic duct , also known as the duct of Wirsung . This duct joins the common bile duct , which comes from the liver and gallbladder. The combined ducts then empty into the duodenum , the first part of the small intestine.
Most of the cells in the pancreas are exocrine . They produce and release pancreatic juice , which flows through the pancreatic duct. This juice contains enzymes that help digest fats, carbohydrates, and proteins in food. The daily volume of pancreatic juice is about 1.5 liters .
A small number of cells in the pancreas (less than 1%) are endocrine . These are grouped in clusters called islets of Langerhans . These islets produce and release hormones such as insulin and glucagon.
Insulin , produced by the beta cells of the islets of Langerhans , reduces the amount of sugar in the blood when it is too high. Glucagon , produced by the alpha cells of the islets of Langerhans , increases the amount of sugar in the blood when it is too low.
Changes in the cells of the pancreas can lead to the formation of benign (non-cancerous) tumors.
Expert perspective
A benign tumor of the pancreas forms a mass of cells that does not spread to other parts of the body.
Among the non-cancerous pancreatic tumors are pancreatic pseudocysts , which are fluid-filled sacs. A pseudocyst is usually caused by an injury or pancreatitis . This pancreatitis can be acute , appearing suddenly and resolving quickly, or it can be chronic and last longer.
The treatment for a pseudocyst varies depending on its size and the symptoms (abnormal manifestations caused by a disease) it may cause. Most of the time, there are no symptoms, and simple monitoring will be done. However, a large pseudocyst or one causing symptoms such as abdominal pain, nausea, jaundice, or fever will require intervention, which may include surgery.
Other benign tumors include serous cystadenomas , which have a very low risk of malignant degeneration. These are the most common cystic lesions with few symptoms, and they are typically discovered at an average age of 60-70 years.
On the other hand, some lesions are precancerous conditions. This is the case with mucinous cystadenomas , which have a high degenerative risk and affect women 20 times more often than men. They have few symptoms, and the average age of discovery is 40-50 years.
Among the precancerous lesions are intraductal papillary mucinous tumors of the pancreas (IPMNs) , which are often discovered incidentally at an average age of 65, with a risk of malignant transformation of about 15%. Finally, there are pancreatic intraepithelial neoplasms (PANINs) , which are microscopic lesions that can progress from a benign lesion stage to invasive cancer.
Changes that affect the cells of the pancreas can also transform them into cancerous cells, leading to the formation of malignant tumors, known as pancreatic cancer.
Expert perspective
About 95% of pancreatic cancers originate in the cells of the pancreatic duct. This type of cancer is called pancreatic ductal adenocarcinoma . In 2 out of 3 cases, the cancer affects the head of the pancreas.
Other types of pancreatic cancer are rare, including pancreatic neuroendocrine tumors , which derive from the endocrine cells of the pancreas. They account for only 1% of pancreatic tumors.
These neuroendocrine tumors are mostly benign, but some can be malignant.
Among these neuroendocrine tumors, insulinomas represent 35 to 45% of pancreatic neuroendocrine tumors. They develop from the beta cells of the Islets of Langerhans and produce large amounts of insulin. It is benign in 90% of cases and malignant in 10% of cases.
Glucagonomas develop from the alpha cells of the Islets of Langerhans and produce large amounts of glucagon. These are typically malignant tumors.
The average time between the appearance of the first cancer cell and the formation of a malignant tumor is estimated to be 12 years (source: arcagy.org). Cancer cells can migrate from the pancreas to other organs to form metastases. The average time between the formation of a malignant tumor and the appearance of metastases is about 7 years.
TO REMIND YOU
The formation of metastases is the real issue posed by cancer.
Without metastasis, treating the primary tumor with local treatment, such as surgery or radiotherapy , would be enough to cure most cancers.
The presence of metastases results from the spread of cancer cells distant from the primary tumor and requires the use of treatments that also spread throughout the body (systemic treatments), such as chemotherapy, targeted therapies, hormone therapies, or immunotherapies .
This spread of cancer cells to form metastases is a complex process, as the cancer cells must leave the primary tumor, use lymphatic vessels and/or blood vessels to circulate through the body, then exit these vessels and penetrate a new organ to multiply and form metastases.
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Article updated on Jan 21, 2025
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