Colorectal (Colon) Cancer: Symptoms, Causes & Prevention

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According to statistics from the Singapore Cancer Society, colorectal cancer is the top diagnosed cancer in Singapore – no.1 in men and no.2 in women.

What is Colorectal Cancer?

Colorectal cancer is cancer of the colon (the main part of the large intestine) or the rectum (the passageway connecting the colon to the anus). Sometimes it is called colon cancer, for short.


Colorectal cancer is cancer of the colon or the rectum
The colon is the large intestine or large bowel. The rectum is the passageway that connects the colon to the anus. Photo: CDC

Colon Cancer symptoms

Colorectal cancer does not always cause symptoms, particularly in the early stages. Someone may have colorectal cancer and be unaware of it.

According to the Centers for Disease Control and Prevention, signs and symptoms of colon cancer may include:

  • A change in bowel habits.
  • Blood in or on your stool (bowel movement).
  • Diarrhea, constipation, or feeling that the bowel does not empty all the way.
  • Abdominal pain, aches, or cramps that don’t go away.
  • Losing weight and you don’t know why.

Consult a doctor if you experience any of these symptoms. They could be the result of something other than cancer. Seeing your doctor is the only way to find out what’s causing them.

What causes Colorectal Cancer?

The exact causes are unknown, but colon cancer has several potential risk factors:

Polyps in the colon or rectum

The majority of colorectal cancers begin as a growth on the lining of the colon or rectum. These growths are called polyps. Some polyps can develop into cancer over time (usually many years), but not all polyps do.

There are 3 different types of polyps, according to the American Cancer Society

  • Adenomatous polyps (adenomas): These polyps sometimes change into cancer. Because of this, adenomas are called pre-cancerous conditions. The 3 types of adenomas are tubular, villous, and tubulovillous.
  • Hyperplastic polyps and inflammatory polyps: These polyps are more common, but in general they are not pre-cancerous. Some people with large (more than 1cm) hyperplastic polyps might need colorectal cancer screening with colonoscopy more often.
  • Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA): These polyps are often treated like adenomas because they have a higher risk of colorectal cancer.

Having an inherited syndrome

A person might inherit a genetic predisposition toward colon cancer from close relatives, especially if a family member received a diagnosis before the age of 60 years old.

Traits, habits, and diet

Age is a significant risk factor for colon cancer, a majority of people with colon cancer are older than 50. However, the rates of colon cancer in people younger than 50 have been increasing

Lifestyle factors that may increase the risk of colorectal cancer include:

  • Inactivity on a regular basis.
  • A diet is deficient in fruits and vegetables.
  • A high-fat, low-fiber diet, or a diet high in processed meats.
  • Obesity and being overweight
  • The use of alcohol.
  • Tobacco consumption.
Getting regular physical activity may help lower your risk of getting colon cancer
Getting regular physical activity may help lower your risk of getting colon cancer

Underlying condition

  • Having type 2 diabetes
  • Inflammatory bowel disease such as Crohn’s disease or ulcerative colitis.
  • having undergone radiation therapy for other cancers

How to reduce the  risk of getting  Colorectal Cancer

There are 6 effective ways you can do to help lower your risk:

Take control of your weightBeing overweight or obese increases your risk of getting and dying from the colon or rectal cancer. Eating healthier and increasing your physical activity can help you control your weight.

Get regular exerciseIf you are not physically active, you may have a greater chance of developing colorectal cancer. Being more active may help reduce your risk.

Drink less alcoholAlcohol use has been linked with a higher risk of colorectal cancer. It is best to not drink alcohol. But if you drink, limit yourself to not more than two standard drinks a day:

One standard drink is roughly equal to:

  • One can of beer (285ml)
  • One glass of wine (120ml)
  • One measure of liquor (30ml)

Eat lots of vegetables, fruits, and whole grainsDiets that include lots of vegetables, fruits, and whole grains have been linked with a decreased risk of colon or rectal cancer. Also, eat less red meat (beef, pork, or lamb) and processed meats (hot dogs and some luncheon meats), which have been linked with an increased risk of colorectal cancer.

Don’t smokePeople who have been smoking for a long time are more likely than people who don’t smoke to develop and die from colon or rectal cancer

Get screened for colorectal cancer: Screenings are tests that look for cancer before signs and symptoms develop. These tests can find colon or rectal cancer earlier when treatments are more likely to be successful.

Where to get tested

You can arrange a clinic visit online at MaNaDr application to see a doctor if you are showing any symptoms.

Consult a doctor online to get the best treatment

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Reference: Center for Disease Control and Prevention, Colorectal (Colon) Cancer

American Society, About Colorectal Cancer

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