What is Gastrointestinal Cancer?
The gastrointestinal (GI) tract includes the stomach, small intestine, large intestine (colon), rectum, anus, as well as organs that aid digestion, such as the pancreas, liver and biliary system.
GI cancer arises when various DNA mutations or defects cause abnormal and unregulated cell growth in various locations, forming a tumour. Cancer has a multitude of possible causes, and risk factors include family history and lifestyle choices.
Which Gastrointestinal Cancer is the most common?
Based on the Singapore Cancer Registry’s latest Annual Report, colorectal cancer is the most common type of gastrointestinal cancer in Singapore, comprising 16.9% of cancers in men and 13.1% of cancers in women. Liver and stomach cancer are the 2nd and 3rd most common gastrointestinal cancers, respectively.
Which Gastrointestinal Cancer is the most fatal?
Colorectal cancer, being the most common gastrointestinal cancer, also has the highest absolute number of deaths, accounting for 14.5% of all cancer-related deaths in men and 15.6% in women.
However, among the most common cancers for 2015-2019, pancreatic and liver cancer
had the poorest 5-year survival rates for males (12.2% & 25.5% respectively), while stomach cancer had the lowest survival rates for females at 39.7%.
Pancreatic cancer: the silent killer
While both stomach and pancreatic cancer account for the poorest 5-year survival rate in patients, pancreatic cancer is usually considered to be more deadly as there are no official screening tests to catch it in its early stages compared to stomach cancer.
Hence, pancreatic cancer is a silent killer as it is hard to detect until it has reached late stages or spread, resulting in some of the highest mortality rates of all cancers. Additionally, pancreatic cancer does not respond as well to commonly used cancer treatment, so there are fewer treatment options.
In Singapore, it accounted for 3.2% of cancers in men and <2.8% in women, but 6.3% of cancer deaths in men and 6.7% in women in 2019. This means that despite the relatively lower prevalence of this cancer, it has a disproportionately high mortality rate.
How quickly does each cancer spread?
The rate of spread depends on the type of cancer and its aggressiveness, and varies greatly depending on the underlying mutations. It can range from months in extremely aggressive cancers, to years in slow-growing cancers.
The ‘slow-growing’ types take years to develop into a sizeable tumour that may cause symptoms. Hence it is important for regular endoscopic screening for cancers such as stomach and colorectal cancer, to pick up any pre-cancerous masses.
What are the Symptoms of Gastrointestinal Cancer?
General symptoms of cancer include fatigue, unintentional loss of weight and loss of appetite. Each of the GI cancers has its own unique symptoms, which we will briefly cover below.
- Dysphagia (difficulty swallowing) - solid food, then liquids later on
- Vomiting after meals
- Hoarse voice
- Abdominal bloating, pain or discomfort
- Loss of appetite
- Bleeding (vomiting blood or passing out blood in stools)
- Early satiety (the sensation of being full after eating very little)
- Abdominal pain
- Blood coating the stools or mixed inside
- Altered bowel habits (constipation, diarrhoea, or both)
- A change in stool calibre or shape
- Sensation of incomplete defecation
Liver Cancer (Hepatocellular Carcinoma)
- Abdominal pain
- Jaundice (yellowed appearance of skin or eyes)
- Ascites (fluid accumulation in the abdomen)
- Abdominal or lower back pain
- Jaundice (yellowed appearance of skin or eyes)
What are the tests used to diagnose Gastrointestinal Cancer?
Oesophageal, gastric and colorectal cancers may be diagnosed via endoscopy - Oesophago-Gastro-Duodenoscopy (OGD) to visualise the upper GI tract (oesophagus, stomach, part of the small intestine), and colonoscopy for the lower GI tract (large intestine, rectum) Even in the absence of symptoms, endoscopic screening is recommended for adults starting from the age of 50 (or earlier if one has risk factors which your doctor will advise you on).
An endoscopy is done by inserting a flexible, thin tube, with a camera attached to the end down your throat in an OGD, or via the anus in a colonoscopy. This enables your doctor to visualise the appearance of your gastrointestinal tract and take samples of your tissue if required. Any inflammation, bleeding or abnormal masses can be easily seen, and biopsies (tissue samples) sent for testing if needed, to confirm the diagnosis of cancer.
For liver or pancreatic cancer, since both organs are unable to be visualised via endoscopy, a computerised tomography (CT) scan or Magnetic Resonance Imaging (MRI) are usually done. A CT scan combines multiple X-ray images into a computer system which generates cross-sectional images of your body, whereas an MRI uses strong magnets and radio waves.
Cancer is diagnosed based on histology (appearance of cells under the microscope), while staging is determined by the TNM system (Tumour-Nodes-Metastasis).
To determine the stage, a CT Thorax-Abdomen-Pelvis is commonly done to assess the size of the tumour, depth of invasion, and whether it has spread to adjacent organs or lymph nodes.
If there is suspicion of lymph node invasion, a fine needle aspiration cytology (FNAC) or biopsy (FNAB) may be performed on the lymph node. It involves inserting a needle into the lymph node (under local anaesthesia) to withdraw tissue samples for further examination under the microscope, to determine the presence of cancer cells.
This is just a general overview of commonly used diagnostic tests; your doctor will tailor the tests & scans according to the type and location of cancer.
Is it Cancer or Irritable Bowel Syndrome (IBS)?
The symptoms of colorectal cancer and IBS have some overlap, with both having:
- Abdominal cramps, pain or discomfort
- Altered appearance of stools (eg. constipation, diarrhoea, mixed, mucoid)
- Sensation of incomplete defecation
However, colorectal cancer has additional concerning symptoms like blood in stools, a change in stool calibre or shape, unexplained weight loss or loss of appetite.
How do I know if I have Gastritis or Cancer?
Gastric cancer and gastritis have some similar symptoms:
- Early satiety (feeling full soon after eating)
- Abdominal pain & cramps
Gastric cancer is more prevalent in Asia than Western countries, accounting for 50% of worldwide stomach cancer cases. It is thought to be associated with Helicobacter Pylori infection, a bacteria that causes gastritis/duodenitis and stomach/duodenum ulcers. Additionally, gastritis causes chronic damage to the stomach lining, which marginally increases the risk of gastric cancer.
Is Gastrointestinal Cancer curable?
Depending on the stage at which the cancer is diagnosed, it may or may not be curable. For instance, in an early stage when the tumour is relatively small and has not spread beyond the organ itself, it may be curable after surgical removal of the tumour and chemotherapy/radiotherapy.
However, in late-stage cancers, when the tumour is too large to be removed safely or has spread to other parts of the body (metastatic cancer), there is a poorer prognosis. Treatment for those will be to manage symptoms, reduce pain/discomfort, or shrink the tumour, but it cannot be cured.
What are the Treatments available for Gastrointestinal Cancer?
The aim of cancer treatment can be to cure & achieve control or to palliate symptoms & provide comfort care. Cancer treatment is highly personalised according to the type & stage of cancer, the patient’s choice, and long-term care goals, and should be discussed in detail with your doctor and family members.
If the goal is to cure the cancer, surgery is done to remove or reduce the size of the tumour, and used in combination with either chemotherapy or radiotherapy, which kill or reduce the further proliferation of cancer cells. Once the surgeon has determined that there are minimal remaining cancer cells, the patient will continue with regular doctor’s appointments to undergo blood tests & surveillance scans to check for any recurrence.
If the cancer is determined to be too advanced to be cured, palliative treatment may be offered. Surgery, chemotherapy or radiotherapy may be offered to relieve the symptoms of a large tumour, but the goal is not to cure or remove it entirely. Pain management is a key aspect of palliative care, with options such as analgesics and nerve blocks available.
How can I reduce my risk of developing Gastrointestinal Cancer?
There are various risk factors for developing cancer, such as a family history of similar cancers, chronic inflammatory diseases, an unhealthy diet, smoking, excessive alcohol consumption, etc. While some risk factors are non-modifiable, one can reduce the risk of cancer by cutting down on alcohol intake & smoking, having a healthy diet, and attending routine health screenings to ensure that any cancers are detected in the earlier stages.
Living with Gastrointestinal Cancer
While the diagnosis of cancer is certainly concerning and stressful, it is not always a death sentence. With a rigorous treatment regime, regular scans and frequent appointments with your doctor, it is possible to manage the disease and its symptoms, and potentially go into remission. Psychological support for the patient and their family is also essential in getting through such health challenges.
In conclusion, there are many types of gastrointestinal cancers, each with its unique symptoms and risk factors. On top of leading a healthy lifestyle, it is essential to undergo regular health screenings and highlight new, unexplained symptoms to your doctor so that any diseases can be discovered and treated as early as possible.
- https://journals.lww.com/ajg/pages/articleviewer.aspx?year=2021&issue=03000&article=00014&type=Fulltext. Accessed 25 July 2022.
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- “Gastrointestinal Cancers.” American College of Gastroenterology, https://gi.org/topics/gastrointestinal-cancers/. Accessed 25 July 2022.
- “Singapore Cancer Registry Annual Report 2019.” National Registry Of Diseases Office, 28 January 2022, https://www.nrdo.gov.sg/docs/librariesprovider3/default-document-library/scr-2019_annual-report_final.pdf?sfvrsn=fa847590_0. Accessed 25 July 2022.
- “Stomach cancer incidence rates among Americans, Asian Americans and Native Asians from 1988 to 2011.” NCBI, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4430761/. Accessed 25 July 2022.