What is Pancreatic Cancer?
Our bodies are made up of many different kinds of cells that routinely grow and divide in an organised way throughout our lifetime. When these cells multiply and grow in an uncontrolled or abnormal way, then cancer can develop.
Pancreatic cancer occurs when the cells in the pancreas organ begin to grow and form a lump. This growth can interfere with the way that your pancreas functions.
These alterations in cell growth are most commonly caused by changes, called mutations, in the DNA that carries the instructions the cells follow when they grow. Mutations can confuse the cell, which means it does not stop growing when it should. It is not always clear why mutations happen. Some are inherited from your parents and others happen over time while you age. 5-10% of pancreatic cancers are caused by inherited mutations.
What is the pancreas?
The pancreas is a leaf shaped organ in your body that can be found between the stomach and backbone and is part of your digestive system.
It has two important functions:
- producing enzymes which break down food to allow the body to absorb nutrients
- producing a range of hormones including insulin which help keep the level of sugar in your blood at a steady level
There are three main parts of the pancreas which are called the head, body and tail.
The head is the widest part of the organ nearest to the small intestine and is the most common site of pancreatic tumour growth. The body is the middle section and around 15% of cancers are found here. Finally, the tail is the thinnest part of the pancreas. Only 5% of pancreatic tumours are found here.
Types of pancreatic cancer
Not all cells in the pancreas are the same. They differ depending on the role that they play.
The cells in the pancreas that produce pancreatic enzymes are known as exocrine cells. Exocrine pancreatic tumours are made up of these cells and are the most common type of pancreatic cancer.
9/10 (90%) of exocrine pancreatic cancer is known as pancreatic ductal adenocarcinoma (shortened to PDAC). This particular cancer develops in the channels, known as ducts, which carry pancreatic juice from the pancreas into the small bowel. Other types of exocrine cancers are rare.
The cells that produce hormones are known as endocrine cells. Tumours that grow from these cells are known as endocrine cancers. They account for only 5 in 100 (5%) of all pancreatic cancers. These tumours can also called pancreatic neuroendocrine tumours (PNETS) or islet cell tumours.
Endocrine pancreatic tumours are treated differently to exocrine tumours so it is important to know what kind of pancreatic cancer you have.
Stages of pancreatic cancer
The stage of a cancer reflects the size of the cancer and how far it has spread.
This means knowing the size of the tumour (T), if there are any cancer cells present in the lymph nodes (N) and if the cancer has spread from the pancreas to any other organ in the body (M). This is described as the TNM stage of a cancer and gives a stage from 1-4
Stage 1 – the earliest stage and the cancer is found only in the pancreas.
Stage 2 – the cancer has spread into nearby tissues and/or there is cancer in lymph nodes near the pancreas.
Stage 3 – the cancer has spread into the large blood vessels near the pancreas and/or the stomach, spleen or large intestine.
Stage 4 – the cancer has spread to distant sites such as the liver, lungs or bones.
Risks and signs of pancreatic cancer
Pancreatic cancer is unusual before the age of 40, more commonly in those over 70 years of age.
Risk factors for pancreatic cancer include
- tobacco smoking
- Chronic pancreatitis (inflammation of the pancreas)
- Hereditary pancreatitis
Signs and symptoms can be similar to common illnesses and are as varied as upper abdominal pain, jaundice (yellowish skin and whites of the eyes), dark urine, loss of appetite, weight loss, bowel problems or blod clots, but these may not appear until pancreatic cancer is quite advanced and surgical removal is not possible.
Pancreatic cancer can be treated with surgery, radiotherapy, chemotherapy or palliative care, or a combination of these.
One reason for the poor outcomes for pancreatic cancer is that it is often diagnosed late. By the time someone has symptoms, goes to their doctor and is diagnosed, the cancer is very often quite advanced. About 15% of patients can have surgery to remove their pancreas, which gives the only chance of cure.
Pancreatic ductal adenocarcinoma typically has a very poor outcome: after diagnosis 20–25% of people survive one year and 5% live for five years. Even in those lucky enough to have surgery, only 25–30% will live for five years. Only 1% will survive their cancer for 10 years or more after diagnosis.
For those whose pancreatic cancer has spread into other parts of the body and surgery is not possible, patients will live about six months to a year.
Gemcitabine was the chemotherapy standard for many years for people with advanced pancreatic cancer. Then from 2007, doctors began to combine Gemcitabine with other drugs that target specific abnormalities within cancer cells, as in the case of Erlotinib (Tarceva) which blocks chemical signals causing cancer cells to multiply. While these combinations, including with Capecitabine, improves the way Gemcitabine works, they have still not significantly changed survival rates.
More recently, the Gemcitabine plus nab-Paclitaxel (Abraxane®) and FOLFIRINOX combinations have become the standard of care for patients who are well enough to cope with the significant side effects. However, these newer treatments only extend survival by a few months at best – the two-year survival rate for advanced disease remains less than 10%.
Importantly, there are small groups of patients who will derive significant benefit from some of these therapies. Identifying these patients before commencing treatment, and not giving treatments to patients when they will not work may seem obvious, but this is the current challenge facing doctors involved in cancer care.
As pancreatic cancer spreads to nearby lymph nodes and other organs, the increasing burden of symptoms means that patients are no longer well enough to have surgery, radiotherapy or chemotherapy and the primary medical focus is on making the patient comfortable.