Are Your Colon Polyps Cancerous? 

Colon polyps are a common occurrence affecting 15 to 20 per cent of the population in Singapore. While most polyps are usually benign, a small number of them can become cancerous. More than 90% of patients with colon cancer have had colon polyps, showing its prevalence.  

But what exactly are colon polyps? Which types of polyps are cancerous and how should you treat them? Read on to find out more about the warning signs of cancerous colon polyps and the treatment options available.  

Understanding Colon Polyps 

Colon polyps are tiny bump-like growths along the inner lining of the colon. They are usually benign (non-cancerous), though they can develop into cancerous tumours over time. There are various types of colon polyps, broadly classified as neoplastic and non-neoplastic. Neoplastic polyps (adenomas) are precancerous, meaning they can potentially develop into cancer (carcinomas).  

Neoplastic polyps 

Common types of neoplastic polyps include: 

  • Adenomatous: A type of polyp that comes in various shapes and sizes, appearing as bumps. Some are flat, others have a stalk that gives them an irregular, rough-like appearance. This is further categorised by their growth patterns: tubular vs villous. Tubular polyps are smaller, and the tube-like cells are arranged in rows, while villous polyps are larger, with finger-like projections covering a wider area. A third type of adenoma called tubulovillous involves a mixture of tubular and villous growth.  
  • Serrated: They have a saw-tooth appearance further classified into sessile polyps, where polyps are flat and broader, and traditional serrated polyps, a rare form often seen in the distal colon.  


Non-neoplastic polyps 

Non-neoplastic polyps do not become cancerous: 

  • Hyperplastic: A type of serrated polyp that is small and smooth. They are usually found in the distal colon.  
  • Juvenile: Polyps that grow in children and youths typically below 20 years old.  
  • Inflammatory: Colon inflammation e.g. colitis creates ulcers that when healed will form a scar that resembles a polyp (pseudopolyp).  

Polyps are also measured by dysplasia, which describes abnormal changes in the cells of tissues, which is a sign of cancer. Low-grade dysplasia indicates polyps are only mildly abnormal, but high-grade dysplasia is used to describe huge changes to the size and shapes of cells, which can be precancerous.   


Are Your Colon Polyps Cancerous? 

Colon polyps can be benign or precancerous, with some having the potential to become cancerous over time. However, certain risk factors can increase the likelihood of colon polyps becoming cancerous. 


Risk Factors for Cancerous Colon Polyps 

Colon polyps can happen to anyone. Nonetheless, you may be at greater risk if you have the following:  

  • Neoplastic polyps that are larger than 1cm  
  • Age: Increased risk as one gets older (45 and above) 
  • Genetics: Polyps develop into cancer when genes that suppress tumour growth are inactivated, usually due to genetic mutation. Familial adenomatous polyposis (FAP) is a genetic condition caused by a defective tumour suppressor gene called adenomatous polyposis coli (APC). This causes thousands of polyps to grow in the colon. If left untreated, the polyps have a near 100% chance of turning cancerous. Other conditions like Gardner syndrome and Peutz-Jeghers syndrome have similar effects.  
  • History of inflammatory bowel disease e.g. colitis, Crohn’s disease 
  • Lifestyle factors e.g. smoking, alcohol, sedentary lifestyle 

Colon polyps and early signs of colon cancer are typically asymptomatic until they are already in their advanced stages. Hence, regular colorectal screening is important in detecting and removing precancerous colon polyps before they turn cancerous.  


Signs of Cancerous Colon Polyps 

Colon polyps, both cancerous and benign, usually do not cause any symptoms. However, in some cases, cancerous polyps are more likely to display signs such as: 

  • Blood in stool from rectal bleeding 
  • Change in bowel habits e.g. frequent constipation or diarrhoea  
  • Abdominal pain due to blockage in the colon  
  • Iron deficiency: Bleeding from polyps may lead to anaemia (low RBC count), which can lead to fatigue and shortness of breath 

Certain genetic diseases like FAP also present visible symptoms such as bumps all over your body, freckles, and unexplained weight loss. If you notice any changes in your digestive health, seek a consultation with a gastroenterologist as soon as possible.  


Diagnostic Procedures 

Colorectal cancer is one of the most common cancers in Singapore, with more than 1,500 cases diagnosed per year. While only 5-10% of all polyps become cancerous, more than 95% of colon cancers start with colon polyps. Diagnostic testing is vital in determining the type of polyps you may have, which will be useful in estimating the risk of cancer and removing the polyps before they turn cancerous.  

Colon screening is the most common diagnostic method to visualise signs of polyps or tumours in the colon. You may need to fast or take a laxative the night before the screening to ensure that the colon is clean for clearer visualisation. Depending on your condition doctors may deploy one of these few screening methods:  

  • Colonoscopy: It involves the insertion of a colonoscope via the anus to view the inside of the rectum and colon to check the number, size, location, and shape of polyps or cancerous tumours. This procedure, around one hour, is performed under sedation, hence you should feel little to no discomfort. Sigmoidoscopy is a similar process but only examines the sigmoid colon, which is located at the lower part of the large intestines.  
  • Barium Enema: An X-ray of the colon and rectum by injecting barium liquid into the colon through a rectal tube. The barium absorbs X-rays, which allows doctors to visualise the colon through X-ray images and highlight any anomalies.  

 If the screening shows any anomalies, further tests may be performed:   

  • Stool test: The DNA and cells will be examined to identify whether they are cancerous.   
  • Blood test: A low red blood cell count (anaemia) may be indicative of chronic colon bleeding, which is a risk factor for colon polyps and cancerous growth. 
  • Genetic test: This is useful for those with a family history of colon cancer or FAP to check if you carry the mutated gene for colon polyps.  


Treatment Options 

If detected early, cancerous colon polyps have a good prognosis. The recent advancements in screening and treatment methods have made it more viable to remove polyps of various sizes.   

If cancerous polyps are small and localised, they can be removed through polypectomy, a procedure during colon screening where a wire loop is attached to the colonoscope to remove the polyp. For larger polyps, they will be removed along with the surrounding tissues to ensure complete removal via a minimally invasive surgery called laparoscopy. A small incision is made on the abdomen, and a laparoscope is inserted into the colon to remove the polyp.   

Should the polyps develop into cancer, a range of therapies like chemotherapy, immunotherapy, and targeted drug therapy are viable options to kill off the cancer cells. Surgery will be the last resort and performed only when the cancer has spread too far. Depending on the severity of the condition, either a portion of the colon (partial colectomy) or the entire colon (total colectomy) will be removed.   


Preventive Measures 

While we cannot escape the genetic fate that causes colon polyps, we can still reduce the risk of developing them via lifestyle changes. Avoid smoking and excessive consumption of alcohol, which contains carcinogens (cancer-causing chemicals). Maintain a clean diet with low-fat foods and increase fibre intake like fruits and vegetables.  

Obesity is a risk factor for colon polyps. Hence, maintain a healthy weight through a good diet and exercise. Try to incorporate at least 150 minutes of moderate to vigorous exercise per week. If exercising sounds daunting to you, try to just take a 20 to 30-minute walk every day. The key to consistency is to find something that you enjoy. If you hate running, there are various other low-impact options like swimming, pilates, yoga and more.  

Colon polyps and cancer act as silent killers – you don’t know they are there until the damage is done. While you may not feel any different, the cancerous polyps could be slowly marking their territory already. Even after you have removed any colon polyps, there is still a risk of polyp regrowth. Hence, regular screening is useful in detecting early signs of cancer, which facilitates early treatment.  


Early Detection Saves Lives 

Early detection starts with being aware of changes in your body. If you notice any symptoms like diarrhoea, constipation, cramps, rectal bleeding, and/or unexplained weight loss, seek a professional immediately.  

It is recommended to go for a colon screening every 5 to 10 years, especially once you hit 45 or have a family history of colon cancer. If you have a history of colon polyps, you may be required to do a screening every 3 years.  

 Do not self-diagnose or assume things about your symptoms. Some overlapping signs and factors need to be taken into consideration by professionals so that the treatment is personalised for your needs.  



Colon polyps are mostly harmless. However, certain types of colon polyps like adenomatous and serrated polyps carry a higher risk of developing colon cancer. As these polyps seldom have visible symptoms till their later stages, colon screening is essential to detect cancer earlier for a better prognosis.   

 While treatment options for cancerous colon polyps are advancing, prevention will always be the optimal solution. Leading a healthy lifestyle will go a long way in minimising not just the risk of developing colon polyps, but also a range of other diseases as well.  


Protect Your Health Today 

Many people with colorectal cancer don’t have any symptoms at first. When symptoms appear, often the cancer has advanced hence it is important to have regular colorectal screening to detect them.  

Visit us at the Centre for Screening & Surgery for your colon screening today. Our clinic specializes in cancer screeningand treatment of cancersat an early stage with minimally invasive procedures.  

 Call us to book an appointment! 

Recommended articles