A change in your bowel habits, such as diarrhoea or constipation, could be harmless, or it could signify something more serious such as colon cancer. Did you know that colon cancer is the commonest cancer in Singapore? Its symptoms can also include persistent abdominal discomfort or pain.

Dr Melissa Teo Ching Ching, Head and Senior Consultant from the Division of Surgical Oncology at National Cancer Centre Singapore, gives detailed answers to your questions.

Question by riccia

Hi Dr Melissa,

My wife was diagnosed with stage 3 colon cancer and currently undergoing treatment at SGH, doing chemo and radio.

Doctor says she need to remove part of the colon with the tumour next month.

She already underwent 2 months of chemo and radio. Currently her chemo will stop for one month to prepare her for surgery. My questions:

  1. Is it a must she need to remove her colon as part of her treatment ? Even though if the MRI eventually shows that the tumour has subsided ?
  2. Since her chemo has stop now, can she start to consume food like lingzhi, ginseng to help to boost up her body and immune system ?

I am worried certain food will also boost up the growth of cancer cells.

Please kindly advice.



Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Yes. Surgery is the only curative treatment for colorectal cancer. Chemotherapy and radiotherapy are used together with surgery, either before (neoadjuvant) or after (adjuvant) the surgery to further increase the rate of overall and/or disease-free survival.

In your wife’s case, chemotherapy and RT is used before surgery, as a form of neoadjuvant treatment, with the intention of decreasing the chance of local recurrence which means to decrease the chance of the cancer coming back at the same place. Occasionally, repeat imaging after chemo- and radiotherapy shows a marked improvement of the tumour size. However, even an apparent complete resolution of the tumour does not equate to a pathological complete response as microscopic tumour cells would still be present.

This means that in 35 percent of patients receiving neoadjuvant chemotherapy and radiotherapy, no residual tumour is seen on imaging but 65 percent of these patients will still have tumour present microscopically when surgery is performed and the specimen is taken for analysis. As such, your wife would still need to undergo surgery on top of the chemo- and radiation therapy as surgery would remove the entire tumour and is the only curative modality of colorectal cancer.

Many forms of alternative therapy are associated with minimal or no risk. However, there is no compelling evidence that alternative medicine will help to enhance the quality of life or improve the overall survival of a patient. In addition, there are potential toxicities, both direct and indirect, that are related to such therapy.

Firstly, a variety of herbal medications may produce direct side effects such as diarrhea, headache, hypertension, insomnia, nausea and in more severe cases, renal failure. Such alternative therapy may also interact with chemotherapeutic agents and hence should not be used during the course of chemotherapy. Such alternative therapy should also be avoided before surgery as its effect on immunity, bleeding or coagulopathy remain largely unknown.

Question by ktphua

Dear Dr Melissa I have persistent abdominal discomfort and pain on my left abdomen cavity since 2008. Despite gone through Barium Enema, Endoscopy and Colonoscopy, the result shows normal. I have taken omeprazole on long term medication but it does no help to ease the pain. The pain occurs daily and worst if I miss my meal.I still have follow up appointment with Gastroenterology. Meantime,need your advice please. Thank you very much. rdgs, kok too

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

By endoscopy, I assume that you have undergone an Oesophagogastroduodenoscopy (OGD). If not, you may benefit from an OGD. This may reveal gastritis that may be associated with the bacteria Helicobacter Pylori (H Pylori).

H Pylori has been found to be associated more with gastric malignancies and only few studies have shown its relation to colon cancer. Gastritis caused by H Pylori can be treated with triple therapy.

Since the results of your colonoscopy and barium enema are shown to be normal, it is unlikely that you have colon cancer. However, colon cancer is the most common cancer in Singapore. Even without relative risks and a normal colonoscopy, one should have a repeat colonoscopy in ten years (See MOH screening guidelines).

Question by Vivian

My grandma has recently been diagnosed with a stage 4 Colon cancer. She has started her first session of Chemo.

The chemo is in a 3-weeks a cycle for 6 cycles treatment. On a weekly basis, we will need to change the chemo medication for her at home. I read online that these chemo fluid is pretty toxic. And the fluid discharge of the patient is toxic as well. (ie sweat/saliva/urine etc) So, they would advise small kids and pregnant women to have minimal contact with the patient.

I would like to know if the online information is relevant as I have a one year old daughter at home, staying together. Do we need to separate the utensil for my granny as well?

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Chemotherapy drugs are broken down and excreted from the body by the kidney, liver or intestines. Chemotherapy drugs are extremely toxic and have the potential to have an adverse effect on those around the patient once it is removed from the body.

Chemotherapy causes changes in the DNA of the patient and may potentially cause short and long-term effects on those who come into contact with it. Mild side effects include skin irritation or damage.

In general, chemotherapy takes about 2 days to be excreted. During this period, no one should come into contact with the patients’ waste products and fluids. Should any contact be made by accident, one should wash the area of contact thoroughly.

Question by mosmos

Although I do not have colon cancer at this moment, but what are the precautions against colon cancer? Are there any food to avoid? Or are there any food that should be taken to prevent getting colon cancer?

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

There are a considerable number of factors which have been found to be associated with a decreased risk of colorectal cancer such as regular exercise, dietary factors and the regular use of non-steroidal anti- inflammatory drugs (NSAIDS).

Multiple studies have shown that physical activity, high consumption of fruits and vegetables, a diet low in red meat and alcohol but high in calcium and fish, result in a reduced risk of colon cancer. None of these potentially beneficial effects are absolutely protective against the development of colorectal cancer.

Individuals over the age of 50 should undergo colorectal cancer screening, in the absence of symptoms, to allow for early detection of polyps or malignancies.

If one has an increased risk of developing colorectal cancer due to a significant family history or hereditary syndromes such as Familial Adenomatous Polyposis or Hereditary Nonpolyposis Colon Cancer (HNPCC), screening should begin earlier and at a more regular interval (See MOH screening guidelines).

Question by fate-destiny

Hi Doctor,Its A Habit Of My Body To Pass Motion After A Meal Especially In The Morning.I Will Pass Motion At Least 2 Times In Morning & Sometimes 4-5 Times In The Morning And When I Use Tissue To Wipe Away The Stools,There Will Be Blood & I Will Start To Feel Bad In My Anus.Strange Enough,If I Will To Eat Vegetarian Food The Day Before,Next Day I Won't Be Able To Pass Motion At All.Even If I Do Pass Motion,Its Only About 1-2Times Compare To 4-5Times When I Eat Meat Food It Doesm't Have Blood.What's Wrong With My Body & Could It Be Colon Cancer?

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Bleeding from the rectum can be caused by a variety of reasons. These reasons include diverticulosis which is the outpouching of the colonic wall, colitis, hemorrhoids or cancer.

In general, bright red blood is mostly associated with bleeding in the peri-anal region, where the commonest cause is hemorrhoids. Change in bowel habits, as well as blood from the rectum, are both clinical manifestations of colorectal cancer, however other causes of such symptoms cannot be ruled out.

You should consult with a doctor, who may advise a colonoscopy that would be able to identify the cause of the bleeding as well as the reason for the change in bowel habits.

Question by s1630548j

Dear Dr Melissa

I have a friend who is currently 36 years old & she is having diarrhoea & constipation very frequently. Lately she even had regular sever pain on her abdomen.

Please advise what should she do?

Thank you.

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Diarrhea and constipation would be considered a change in bowel habit, especially if these symptoms are of recent onset. A change in bowel habit may arise from benign causes such as food induced changes or more sinister causes such as colorectal cancer or Inflammatory Bowel Disease, which include Crohn’s disease and Ulcerative Colitis.

I would advise her to schedule a medical appointment with the specialist who would be able to take a comprehensive clinical history and perform a thorough physical examination.

Depending on clinical findings, she might be scheduled for a colonoscopy and OGD which would allow the examination of the inside of her colon, oesophagus, stomach and the proximal duodenum to identify the cause of her change in bowel habits as well as her abdominal pain. Radiological investigations such as a CT or ultrasound scan may also be indicated.

Question by tontonrokushi

Funny, I think about the liver when we are supposed to look at the colon. I surmise doctor that colon cancer can't be too deadly (even at Stage 3) as long as we are in the good hands of a colorectal surgeon who will have to remove extensive portion of the colon. But, when the colon cancer has cells which metastasize to the liver, then it's scary! A fortiori, it's fatal if the liver is complicated with cirrhosis. I think the twain disease of colon-liver metastasis is also not uncommon especially when our blood supply that's leaving our intestine really connects directly into the liver. This twain disease puts older folks at higher risk too. Doctor, please let me know what is the survival rates of a colon-liver patient(probably equated to Stage IV colon cancer?) Can we be less pessimistic with a colon-liver patient (as exemplified by Robin Gibbs) when compared to a patient which suffers from primary liver cancer. (Suffice for me here, to ask about comparison with primary liver cancer, because prognosis for liver-colon cancer will almost certainly be dismal, I think)

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Approximately 20 percent of colorectal cancer patients have metastatic disease (Stage 4 disease). The liver is commonest site of metastases of colorectal cancer. In 35% of those diagnosed with stage 4 colorectal cancer the spread is confined to the liver. In these patients, surgical resection of the liver metastases provides patients a long term survival of 40 percent. In patients whose disease is unresectable because of extensive liver involvement or concomitant spread to other organs such as the lungs, the prognosis is dismal with a 5 year overall survival of less than 10 percent.

Primary liver cancer is typically Hepatocellular Carcinoma and is usually found in patients with underlying chronic liver disease such as cirrhosis from Hepatitis B/C or chronic alcoholism. It is an aggressive tumour and is usually diagnosed late in its course with a median survival of 6-20 months. The mainstay treatment is surgical resection. However, only about 20 percent of patients present with resectable disease. In patients with resectable disease, 5 year overall survival ranges from 30-90 percent. In patients with unresectable disease, patients have a median survival of 3-6 months.

Question by Evelyn Wong

What are the symptoms of colon cancer and what are the different types of colon cancer?

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Colorectal cancer can present in many ways depending on the site of the tumour. Right sided tumours usually present with abdominal pain, loss of weight, loss of appetite and iron deficiency anemia while left sided tumours usually present with a change in bowel habit and per rectal bleeding. 60 percent of colorectal cancer patients are asymptomatic and symptomatic presentation is often a result of relatively advanced colorectal cancer.

In more advanced cases, the tumour may cause obstruction which may results in abdominal distension, nausea and vomiting. In patients with metastatic disease, they may present with para-umbilical nodules and discharge, abdominal pain and distension and shortness of breath. A person with any one of the above mentioned symptoms should consult a doctor for medical advice on the appropriate management. In the absence of symptoms, one should do regular screenings for colorectal cancer to allow the detection of polyps and tumours at an early stage (See MOH guidelines).

The commonest type of colorectal cancer would be an Adenocarcinoma of the colon. Colorectal adenocarcinoma follows the AJCC 7th edition staging where stage 1 and 2 are confined to the colon, stage 3 demonstrates lymph node involvement and stage 4 shows distant metastases. There are other types of colorectal cancer such as Lymphoma, Gastrointestinal stromal tumour (GIST) and Carcinoid tumour.

Question by taylk

Dear Dr Melissa

Recently I had a change in my bowel habits.

I tend to open bowels very frequently after I eat.

And each time I open my open bowels, the stools are not hard but it comes out so much about the length of a 12 inch ruler. It can be 5 or 6th times per day. Where on earth does the stool comes from. I am worried as I tend to loose weight as well. What is happening to me?

Answered by Dr Melissa Teo Ching Ching Senior Consultant Dept of Surgical Oncology National Cancer Centre Singapore

Change in bowel habits is associated with conditions such as colorectal cancer and Inflammatory Bowel Diseases which include Crohn’s disease and Ulcerative Colitis. In colorectal cancer, change in bowel habits occurs due to the growth of the tumour within the colon which prevents stool from passing. In some instances, colorectal cancer is associated with a loss of weight and loss of appetite. I would advise you to seek advice from a medical practitioner and it is likely that a colonoscopy would be performed that would allow the examination of the inside of your colon for the detection of any lesions within the bowel.

Ref: T12