Colon Cancer: Common Signs You Should Never Ignore

July 23, 2020

Colon cancer is a cancer that forms in the cells lining the inside of the large intestine. It is usually grouped together with cancer of the rectum and referred to collectively as colorectal cancer.

Colorectal cancer is one of the most common cancers among Singaporeans. According to the Singapore Cancer Registry, between the years 2011 to 2015, colorectal cancer was the most common cancer among men in Singapore, and second most common among Singaporean women. It is also the second-largest cause of cancer-related deaths among men, and the third-largest among women.

Recognising colon cancer

The symptoms of colon cancer can sometimes be overlooked or unnoticed. This is especially so in the early stages of the disease, when the symptoms may be milder, or not even be present. Yet, early diagnosis is crucial as it can expedite life-saving treatment.

As such, colorectal cancer screening tests like the faecal immunochemical test (FIT) or lower gastrointestinal endoscopy are recommended for Singaporeans above 50 years old. Regular screening should be accompanied by vigilance in looking out for early warning signs of colon cancer. Here are some of the noticeable symptoms that you should look out for.

  • Rapid, unexplained weight loss

A sudden drop in weight could be a cause for concern. If you experience a loss of about 4.5kg or more in six months or less without any marked change in your diet or lifestyle, you should consult a doctor about it. Cancer cells tend to use a lot of the body’s nutrients to grow and multiply, which can lead to weight loss.

  • Fatigue and lethargy

Fatigue is a feeling of tiredness that does not go away even with rest. Like unexplained weight loss, this could occur due to the cancer cells depleting the energy stores in the body. This is a rather common symptom shared across many conditions, like diabetes and heart disease, so it should be considered alongside other symptoms.

  • Persistent changes in bowel habits

A tumour that has grown large enough can cause blockage in the colon. This could result in narrower stools or more frequent trips to the bathroom. It could also affect the ability of the large intestine to absorb water, leading to more watery stools. One may experience this as diarrhoea or constipation. If unrelated to another condition, these can be symptoms of colon cancer.

  • Stomach pain

Long-lasting and severe stomach pain that began recently can be a symptom of colon cancer. Colon cancer often causes changes in bowel habits, which can result in cramping and bloated stomach symptoms. Irritable bowel syndrome (IBS) can cause these symptoms as well, in addition to diarrhoea and constipation.

  • Blood in stool

A tumour can lead to bleeding in the colon and blood in the stool. One may notice this from blood on the toilet paper after wiping, or blood in the toilet bowl water. Alternatively, stool could appear very dark or even black due to dried blood. Bloody stool is also observed in cases of ulcerative colitis (UC) or inflammatory bowel diseases, like Crohn’s disease.


While one of these symptoms alone may not be sufficient to determine the underlying condition, multiple symptoms can give your doctor a better idea of the possible causes.

Frequent screening and knowledge of the symptoms of colon cancer could allow for early diagnosis and the provision of life-saving treatment. If you are experiencing these symptoms, want to explore your colon cancer screening options, or find out more about colon cancer treatment costs in Singapore, you can consult a gastroenterology specialist or a general practitioner.