What is Pancreatic Cancer: An Overview
Depending on the tissue or organ where the cancer begins, there are around 200 types of cancers and these are called primary cancers. Some cancers have a high likelihood of spreading from one tissue to another and this is called metastasis. Secondary or metastatic cancers are those that have spread from primary locations but show symptoms predominantly of the secondary type.
The pancreas is a small, spongy organ that is around six to ten inches long and extends horizontally across the abdomen. It is fish or flat pear shaped organ, the wider end towards the centre of the abdomen is called the head, followed by neck, body and tail as we move left towards the narrow end of the pancreas.
This organ plays an important role in converting the food we eat into energy and functions as both an endocrine and an exocrine gland.
To understand the functioning of pancreas, it can be viewed as two separate glands as its functions are of two main types- exocrine and endocrine functions. The exocrine gland consisting of acinar and duct tissues and endocrine gland containing of islets of Langerhans.
Exocrine glands are those that secrete substances into the body through ducts. Salivary, sweat and mammary glands are some examples of exocrine glands.
The majority of pancreas, about 85% by mass is the exocrine portion of the pancreas. It produces enzymes important to digestion along with liver and gallbladder. The important enzymes include:
- Lipase to digest fats
- Amylase to digest carbohydrates
- Chymotrypsin and trypsin for digesting proteins.
Endocrine glands are those that secrete substances into the body directly through the bloodstream. The two main hormones produced by the pancreas are:
- Insulin that lowers blood glucose levels
- Glucagon that works to increase the blood glucose levels
So pancreas is essentially what controls the blood sugar level in the body that plays a significant role in the functioning of liver, kidneys, and the brain and for proper functioning of nervous and cardiovascular system.
When the exact causes of a certain type of cancer are not known, certain factors associated with the cancer are identified and are called risk factors. The presence of a risk factor does not imply that the person develops pancreatic cancer, it only indicates a higher probability. On the other hand, a person may get this cancer even without having any risk factors. The following are the risk factors.
- Older people are more likely to develop this cancer
- Men are more likely to develop this cancer when compared to women.
- Africans were observed to be more prone when compared to other ethnic backgrounds
- Pancreatic cancers seemed more common in people who have a family history of it.
- Tobacco consumption
- Obesity or being overweight
- Chemical exposure of certain substances.
- Genetic syndromes like hereditary breast and ovarian cancer syndrome, familial atypical multiple mole melanoma (FAMMM) syndrome, familial pancreatitis caused PRSS1 gene mutation, Lynch Syndrome, Peutz Jeghers Syndrome etc.
- Inflammation of the pancreas called chronic pancreatitis which damages the pancreas permanently.
- Liver cirrhosis, a condition where the liver is damaged extensively.
Pancreatic cancers are mainly divided into two main categories depending on the part of the pancreas they affect- Exocrine pancreatic cancers and pancreatic neuroendocrine tumours.
In these types of cancers, the exocrine part of the pancreas is affected, that means the secretion of the enzymes becomes unbalanced. Most pancreatic cancers are exocrine in nature. Exocrine pancreatic cancers can be further divided into subtypes-
- Pancreatic adenocarcinoma
- Acinar cell carcinoma
- Intraductal papillary-mucinous neoplasm (IPMN)
- Mucinous cystadenocarcinoma
Pancreatic adenocarcinoma accounts for 9 out of 10 cases of exocrine pancreatic cancers.
Pancreatic neuroendocrine tumours:
Neuroendocrine tumours are tumours in the endocrine glands of the body, in pancreatic neuroendocrine tumours the cancer is in the endocrine part of the pancreas. These are of two types, functioning and nonfunctioning- The functioning pancreatic neuroendocrine tumours produce hormones excessively while the latter type of tumours do not. The outlook of this cancer depends on the type of hormone secreted too and so functioning tumours are classified further into the following types:
Pancreatic cancers do not show symptoms in the early stages and most common symptoms only appear after the cancer has spread outside of pancreas. The symptoms majorly depends on its type. The symptoms of exocrine pancreatic cancers are as follows:
- Pain in the abdomen or back pain
- Unintended weight loss or loss of appetite
- Nausea or vomitings
- Swelling of liver or gallbladder
- Clotting of blood in the legs or in lungs
- Uneven texture underneath the skin
- Jaundice which shows yellowing of skin and white of the eyes
The symptoms of pancreatic neuroendocrine tumours depend on the type of hormone being produced by the tumour, while some of the common symptoms include:
- Muscle spasms
Some of the specific symptoms of pancreatic neuroendocrine tumours are as follows while detailed information about the symptoms of pancreatic neuroendocrine tumours can be found here
- Gastrinoma: Symptoms include stomach ulcers, stomach pain, nausea, decrease in appetite.
- Glucagonoma: Some symptoms of this subtype are diabetes, malnutrition, diarrhea, weight loss, irritation of tongue or mouth.
- Insulinoma: Hypoglycemia (low blood sugar), weakness, confusion, unusual sweating are the common symptoms of insulinoma.
- Somatostatinoma: Irregularities in the production of other hormones such as growth inhibiting hormone, insulin etc are the usual symptoms.
- VIPoma: Low levels of potassium, stomach acid, diarrhea are some of the symptoms of VIPoma.
Staging helps the doctors figure out the on how much the cancer has spread in the pancreas, determine the best treatment and also helps calculate survival statistics. The lower the number of the stage, the less is the cancer has spread.
In this stage, the cancer has not penetrated the inner tissues of the pancreas and is confined to the top layers of the pancreatic duct cells. These tumours are known as carcinoma in situ (Tis).
In this stage, the cancer is present only in the pancreas and the tumour is about 2 cm to 4 cm in size and the cancer has not spread to other parts of the body. The staging here is (T1, N0, M0).
The cancer has spread to lymph nodes but has not metastasized to other parts of the body and is defined as stage 2 regardless of the size of the tumour. The staging here is (TX, N1, M0) where X can be 1, 2 or 3.
In this stage, the size of the tumours could vary 1 cm to 4 cm, or even be bigger than that, along with the cancer being spread to one or more lymph nodes. The staging can be (TX, N2, M0) where X can be 1, 2 or 3 or is (T4, N1, M0).
In this stage, the pancreatic cancer cells have spread to other parts of the body as well. The tumour size is bigger than 4 cm in size and the cancer may or may not have spread to the lymph nodes. The staging here could be (ANY T, ANY N, M1).
Resection and staging:
Another method of staging pancreatic cancer is based on the resection of the tumour. Resection means surgical removal of a tissue or a tumour and a resectable tumour is one that can be completely removed through surgery leading to the elimination of all cancerous cells.
Depending on the resectability, pancreatic cancers can be classified as resectable, borderline resectable and unresectable.
Treatment of pancreatic cancers:
The treatment depends on the type of cancer, the location of the tumour, the spreading and stage of cancer and the patient’s response to treatment. Pancreatic cancers are not often diagnosed in early stages as symptoms are not noticed till the cancer has spread to the other parts of the body and depending on where and how much the cancer has spread, the course of treatment is decided. The methods of treatment available for this type of cancer are as follows:
Surgery is the best method of treatment for pancreatic cancers in the early stages and for some pancreatic neuroendocrine tumours. Surgical procedures are used in removing the tumour and the surrounding lymph nodes if the cancer has not spread beyond the pancreas. Surgeries can be complicated for treating pancreatic tumours depending on the location of the pancreatic cancer. Some of the different surgeries available for pancreatic cancers are:
- Pancreaticoduodenectomy or Whipple procedure
- Partial Pancreatectomy
- Pylorus-preserving procedure
Read more about the surgical procedures of pancreatic cancer treatment here
Chemotherapy is the use of drugs to counter or kill the cancerous cells in the body and is more widespread and can kill the cancer that has spread to other tissues or organs of the body too and hence is the preferred treatment for metastasized cancers and those that are likely to spread too.
Radiation therapy for pancreatic cancer uses high dosage of radiation to kill cancer cells and shrink the cancerous tumours. It is not typically used to treat cancer that has already spread to the other parts of the body and is mainly used post surgery as a part of adjuvant treatment.
When the tumour cannot entirely be removed by the surgery or has already spread to different parts of the body, targeted therapy is used. This treatment uses drugs that interfere with specific tissues that cancer cell growth and survival unlike in chemotherapy where the drugs target the rapidly dividing cells itself.
In cases where the cancer has spread and cannot be completely removed by surgery, the priority is to alleviate or palliate the symptoms of the cancer to improve the quality of life and to make the patient more comfortable. A stent can be placed to remove the blockage caused by the tumour to open the duct and restore the flow of substances. If it is not possible to open the duct through a stent, a bypass procedure may be done too.
Clinical trials is another option for advanced stages of cancer that might have more complications and side effects than the lower stages. Clinical trials focus on new treatments or combination of existing treatments by trying new approaches. While there is some uncertainty attached to clinical trials, it may be the best chances for cases where the traditional treatment have not shown much improvement.
Post active treatment for pancreatic cancer also, the patient has to be checking his/her health regularly. This is to check for any repetition of cancer, manage with the side effects monitor overall health. The following is the follow up care plan for pancreatic cancer.
- Developing a follow-up care plan
- Regular monitoring of blood cell count
- Follow a strict and healthy diet as advised by a nutritionist
- Watching for recurrence of cancer
- Keeping a detailed personal health record
Managing long term side effects:
The patients will have to cope up with the long term side effects that these treatments come with. Mentioned below are some tests that can help monitor the patient’s condition:
- Thyroid examinations
- Lung function
- Regular electrocardiograms (EKGs)
- Computed tomography (CT) scans
The survival rate usually refers to the five year survival rate that shows how many patients out of 100 live beyond five years after first being diagnosed by a specific cancer. It can be an indicator to understand the outlook of the patient based on the type and stage of cancer. The five year survival rates for pancreatic cancer is 12% to 14% for stage I, 5% to 7% for stage II, 3% for stage III and about 1% for stage IV. Pancreatic cancer is fourth leading cause of cancer deaths and is not easily curable in the advanced stages when it is usually detected.