What is a Gastrointestinal Cancer screening?
The gastrointestinal tract (GIT) is an 8-metre long pathway that extends from the mouth to the anus. What we eat first goes into the mouth before passing into the oesophagus, stomach, small intestine (the duodenum, jejunum, and ileum), and eventually into the large intestine (the colon and rectum) before being excreted out through the anus as stools.
In the GIT, water and nutrients from the food we eat are absorbed and processed by the cells lining the gut. Waste products are also removed from our bodies through the rectum and colon. Sometimes, these cells might undergo changes in their DNA (mutations) as we age and turn into abnormal cells. These abnormal cells might be malignant in nature, and a tumour can form in the GIT. Definitive causes for these mutations are not known, but can range from genetic predisposition to lifestyle and environmental causes, and can vary between the different types of gastrointestinal cancers.
Overall, gastrointestinal cancers are common. In Singapore, from 2015-2019, colorectal cancer was the most common cancer in men (16.9% of all cancer cases, Singapore Cancer Registry Annual Report 2019) and the second most common cancer in women (13.1% of all cancer cases, Singapore Cancer Registry Annual Report 2019). While other gastrointestinal cancers, such as stomach cancer and pancreatic cancers, are less common, they too carry a high risk of morbidity and mortality.
Given the large cancer burden worldwide and in Singapore, a myriad of screening programmes have emerged in the country over the years to aid in the early detection of cancers. Cancer screening is a form of secondary prevention, which means that it aims to pick up cancers in their early stages so as to expedite treatment and ensure the best prognostic outcomes, as more advanced diseases are invariably difficult to treat. Screening is done when someone has no symptoms, and it is pivotal in helping to ensure cancers are picked up early. If screening tests come back as abnormal, you may need to have more tests done to find out if you have cancer. These tests are called diagnostic tests.
What are the tests used during the Gastrointestinal Cancer Screening in Singapore?
There are many screening modalities for cancer. With regards to gastrointestinal cancers, colorectal cancers are the ones most commonly screened for here in Singapore.Colorectal cancer is Singapore’s top cause of cancer death.
A note from Dr Benjamin Yip: Whilst colorectal cancer screening is well known, gastric cancer screening is less so. Singapore is a moderate risk zone for gastric cancer, and hence, it is prudent to check with your Gastroenterologist whether you need gastric cancer screening. One should also take note that gastric cancer can strike individuals who are young, i.e. after 30 years of age.
The most common screening tools include a colonoscopy and faecal testing with a faecal immunochemical test (FIT) kit, which requires a stool sample.
In Singapore, free FIT kits are distributed to those aged 50 and above to test for the possibility of colorectal cancer. Although readily available, these tests are not as sensitive to detecting precancerous polyps as a colonoscopy.
A colonoscopy is the mainstay method for detecting colorectal polyps (precursors to colorectal cancer). This procedure involves the insertion of a long, flexible tube with a light and camera at the end through the anus and is guided upwards into the rectum and colon. This allows the gastroenterologist to visualise the lining of the colon and detect any polyps, as well as masses, tumours or bleeding. The attachment of specialised tools to the endoscope also allows the gastroenterologist to remove colorectal polyps during the colonoscopy (polypectomy).
For gastric cancers, screening is done on a discretionary basis, which means that the indications for screening are based on the individual’s medical history and risk factors for stomach cancer.
For gastric cancer screening, an Oesophago-Gastro-Duodenoscopy (OGD), or gastroscopy, is done to check for any abnormal cells in the stomach. Similar to colonoscopy, a thin, hollow, flexible tube with a video camera attached will be inserted through the mouth to visualise the mouth, oesophagus, and stomach. Any abnormal tissue seen will be removed for sampling (biopsy) to be tested by a pathologist, who is a doctor trained in examining tissues in the body.
Advancements in technology have brought about a molecular blood test for the early detection of gastric cancer. Most early-stage stomach cancers have no symptoms. This blood test measures mRNA biomarkers which are present in high levels in patients, even when the cancer is in its early stages. GASTROClear assesses your risk of stomach cancer, and helps your gastroenterologist discern the possible presence of stomach cancer should be followed up with a gastroscopy.
Do I need a Gastrointestinal Cancer Screening?
Generally, it is recommended for both men and women in the general public above the age of 50 to go for colorectal cancer screening.
For other types of gastrointestinal screening, screening is discretionary and will usually only be recommended if you have a medical history that puts you at high risk of the cancer. Various care options and screening follow-ups will be discussed with you along the way with your Gastroenterologist if you are proven to be at higher-than-average risk of cancer.
Cancer screening is pivotal in helping to pick up cancers in their early stages. Early detection generally leads to good outcomes. For one to have the best benefit from cancer screening, it is important to be proactive and aware of the various test screenings available to you.
Some red flags/warning signs that might warrant a trip to a gastroenterologist include:
- Sudden, unexplained, and unintentional weight loss
- Having blood in your stool that is recurrent and does not go away
- Having black stools
- Sudden change in bowel output over the span of a few months, e.g. mixed diarrhoea and constipation, having very thin stools (as thin as a pencil)
In addition, it is also good to continually maintain a healthy lifestyle to minimise your risk of getting cancer. Lifestyle modifications that will help greatly, in the long run, include stopping smoking, reducing alcohol usage, engaging in regular exercise, and maintaining a healthy weight and diet.
- National Registry of Diseases Office. (2022). https://nrdo.gov.sg/docs/librariesprovider3/default-document-library/scr-2019_annual-report_final.pdf?sfvrsn=fa847590_0
- Kisling, L. A., & Das, J. M. (2019). Prevention Strategies. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK537222/
- Maxim, L. D., Niebo, R., & Utell, M. J. (2014). Screening tests: a review with examples. Inhalation Toxicology, 26(13), 811–828. https://doi.org/10.3109/08958378.2014.955932
- Cancer Screening. (n.d.). Www.nccs.com.sg. Retrieved May 7, 2022, from https://www.nccs.com.sg/patient-care/cancer-types/pages/cancer-screening.aspx
- Colorectal Cancer Campaign. (n.d.). Www.singaporecancersociety.org.sg. Retrieved May 7, 2022, from https://www.singaporecancersociety.org.sg/events/campaigns/colorectal-cancer-campaign