Colorectal Cancer

Know the symptoms of colorectal cancer

February 7, 2024 Word for Word Media 0Comment

Dr Daniel Surridge expands on the symptoms and lack of symptoms in colorectal cancer.


You can listen to this article below, or by using your favourite podcast player at pod.link/oncologybuddies

Cancer of the colon and rectum is caused by a slow-growing benign tumour of the bowel which becomes malignant later. It usually takes five to 10 years for this benign lesion to grow into an early cancer and then develop into a late cancer.

During this long time period, there are very few symptoms that the cancer is there at all. In fact, few people with colorectal cancer realise that they have it until it’s very late. In rare cases, like genetic disorders or less common types of cancer, the tumour can grow more quickly.

General symptoms

The most common symptom is a change in the way that you go to the toilet. This can take the form of a change in the usual time of day that you defaecate, an increase or decrease in the usual number of times that you pass stool in a day or unusually hard or runny stools. If you have a prolonged change in the way that you go to the toilet, this is called a change in bowel habit and it may indicate that you have cancer.

Because the colon and rectum can’t feel pain, cancer in this organ doesn’t hurt until very late when it grows or spreads into other organs. This is why it’s a very quiet illness with few symptoms early on. You might lose some weight and have a change in bowel habit as your only symptoms.

If the tumour is slowly bleeding, then anaemia can occur. This is a low level of red blood cells and can cause you to feel tired and listless. Slow bleeding like this is microscopic and you’ll not see any blood in your stool and won’t even know that you are bleeding.

Specific symptoms

Quite often, these general symptoms are so subtle that you will not realise that there is a problem until the cancer has grown quite large or spread. If the tumour becomes very big, it can start to block the bowel and cause an obstruction. This will cause you to feel that you are badly constipated and may even progress to an inability to pass gas or faeces. If you can’t evacuate, the colon and bowel continue to fill and can eventually burst. This is an emergency and requires urgent attention.

If the cancer is low in the colon or the rectum, obvious bleeding may occur. In this case, you will notice fresh blood or clots mixed into or coating the stool.

Symptoms of very late disease

When the cancer becomes very advanced, there are late symptoms that can occur. The loss of weight can become very severe. Blockages of the bowel operations may be needed to create a stoma bag to allow the bowel to empty. When the cancer spreads to the liver and lungs, pain in the abdomen and coughing can become severe.

How to manage your symptoms

Because this cancer takes so very long to grow and there is a stage where there is a benign growth that has not yet become a cancer, it’s possible to prevent colorectal cancer from ever developing. A simple colonoscopy can remove these benign growths and even some of the early cancers before they become a problem.

Unfortunately, because there are very few symptoms of having the benign growth, it’s hard to know when you have this illness. So, it’s hard to decide based on your symptoms when you should have a colonoscopy.

For this reason, it’s usually best to speak to your doctor if you have worries about any of the symptoms above. If any of your direct relatives have colorectal cancer, your risk is higher, and you should see a doctor sooner.

Most screening for this cancer should begin from the age of 45 if you are well and earlier if you have a genetic condition which may lead to the cancer.

Dr Daniel Surridge

MEET THE EXPERT – Dr Daniel Surridge


Dr Daniel Surridge is a subspecialist colorectal and robotic surgeon in Gauteng. He heads up the Joburg Colorectal Unit at Netcare Milpark Hospital. He was formerly the head of colorectal surgery at Chris Hani Baragwanath Academic Hospital which he ran for over seven years, and he has travelled extensively to acquire advanced skills and approaches to colorectal surgery.


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