Understanding colorectal and rectal cancer

by | October 19, 2009

A doctor explains what colon and rectal cancer through a conversation with two fictional patients but based on real-life experiences.

BY: Dr Denis Nyam


Colorectal cancer is the most common cancer in Singapore and it affects men and women with nearly equal frequency. The cancers of the colon (longest part of the large intestine) and rectum (last several inches of the large intestine closest to the anus) usually arise from growths called polyps. Only a small fraction of polyps become cancerous, and most grow so slowly that most people are unaware of them. It is crucial to screen as early detection means a life saved.

Below is more information about these cancers through conversations with the doctor:

Doctor: I am afraid the biopsy results are not very good.

Patient: Oh dear! This is what I have been worrying about the last two days since my colonoscopy. Is it the big ‘C’?

Doctor: I am afraid so. The microscopic examination of the biopsy shows that some cells from the polyp that we removed during the colonoscopy have turned malignant. This means they have the ability to invade and spread to other organs in your body.

Patient: Has it actually spread?

Doctor: The chest X-ray and CT scan shows no evidence of spread and the tumour on the scan shows it might still be limited to the colon. We do not see any enlarged lymph nodes too.

Patient: What does that mean?

Doctor: The possibility of spread is low. Although we do not see it, it does not mean that it has not spread for sure but at least chances are high it has not. We need to perform surgery and remove the whole tumour with its draining lymph nodes and send the whole specimen for histology to make sure.

Patient: What stage of cancer am I in?

Doctor: The scan shows that you are not in stage 4 as there is no evidence of spread. This is good because stage 4 has an extremely low chance of cure.

If the surgical examination shows that lymph nodes are invaded with cancer cells, then you will be in stage 3. This will require you to have chemotherapy after surgery in order to decrease the chance of a relapse later. Stage 1 and 2 are considered early stages in colon cancer and does not require chemotherapy but you will need close follow-up after surgery.

Patient: What are lymph nodes?

Doctor: These are little lumps of tissue, which line the lymphatic system, which drains tissue fluid from all areas of the body. It is like the MRT stations along MRT lines. They act as filters in a body preventing the spread of cancer.

Patient: But doctor, I have only had very mild symptoms of bloating and very little bleeding in my stools for two weeks! 

 Colon and rectal cancer in the early stages have no symptoms and in fact the majority of cancers with symptoms are already in stage 3 or 4.

That is why we are encouraging people to go for screening even when they have no symptoms especially if they are in their 40s or above 50. This is because the risk of cancer increases after the age of 40.

Patient: Doctor, is this cancer that I have common?

Doctor: Yes, it is now the most common cancer in Singapore. We are now seeing almost 2,000 patients diagnosed a year in Singapore.

Patient: How long would I have had this tumour?

Doctor: Possibly years.

Patient: Years?

Doctor: Yes. Often they start as non-cancerous but the pre-cancerous polyp grows slowly. It takes years for a polyp to grow into a cancer and years for a cancer to grow from a few millimetres to the size of a golf ball, which is the size that your tumour is at.

Patient: What? Only two weeks of symptoms and already the size of a golf ball?

Doctor: Unfortunately, yes but I think it is still in the curable stage. We have to discuss the details of surgery … (EDITOR’S NOTE: Colorectal cancer is treated with surgery, and sometimes radiotherapy and/or chemotherapy.)




Patient: Doctor, I have not had any sleep the last two nights. What does the result of my biopsy show?

Doctor: Your polyp is not cancerous …

Patient: I am so relieved!

Doctor: The cells in the polyp show some pre-cancerous activity. It is an adenoma.

Patient: What do you mean? You have removed it right?

Doctor: Yes. We managed to remove it completely. With the colonoscopy, it is possible to completely remove a polyp up to 2cm in size, depending on its position and shape. This means we have prevented you from getting colon cancer in the future.

Patient: Will it recur?

Doctor: Usually polyps do not recur at the same site from which we removed it previously, but a new polyp can form in other parts of the colon as the whole colon is exposed to the same genetic and lifestyle factors.

We have to put you on a polyp surveillance programme depending on your risk profile, which we will arrange after this consultation. 

Patient’s husband: 
Doctor, I am two years older than my wife. Should I also have a colonoscopy even though I have no symptoms?

Doctor: The recommendation is to start screening at 50 years of age. If you have any symptoms related to the lower digestive tract then you should start earlier. If you have a family history of cancer or polyps, you might want to start earlier as well. Let me run through your risk profile … (EDITOR’S NOTE: Besides a strong family history of colorectal cancer, which puts you at risk, there are other risk factors, including consuming a diet that is high in fats and starches, and low in fibre. Also, the screening can include a Faecal Occult Blood Test or FOBT, or colonoscopy.)



You will need to make some lifestyle changes, according to the Singapore Cancer Society:

• Do not overeat.

• Increase fibre intake in your diet.

• Reduce intake of red meat (especially those cooked at high temperatures) and animal fat intake.

• Exercise two to three times weekly.

• Do not smoke.


Dr Denis Nyam is a consultant surgeon at his own private practice, Nyam Colon, Rectal & General Surgery at Mount Elizabeth Medical Centre. For more information on colon and rectal cancer, go to www.singaporecancersociety.org.sg.

SPECIAL THANKS TO: Eileen Goh from Nyam Colon, Rectal & General Surgery.

(PHOTO CREDIT: MALE DOCTOR © Chiyacat | Dreamstime.com)



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