The Colorectal Cancer Basics

6 min read
First Published: 
Mar 2022

Key Learnings contained in this article:

Colorectal cancer is the disease caused when abnormal growths (polyps), in the colon (large intestine or large bowel) or rectum, turn cancerous. It can be called colon cancer for short.

According to the American Cancer Society, colorectal cancer is the third most common cancer (excluding skin cancers) diagnosed in both men and women in the United States.

In this medical writing, the following will be discussed about colorectal cancer:

  • Causes (including risk factors)
  • How to reduce personal risk
  • Symptoms
  • Getting a diagnosis
  • Treatments

What causes colorectal cancer?

Most colorectal cancers start as a growth (polyps) on the inner lining of the colon or rectum.

The disease spreads when cancer forms in a polyp, growing into the wall of the colon or rectum over time. From here the cancer cells can grow into blood vessels or lymph vessels and can travel to nearby lymph nodes spreading throughout the body.

Risk factors

The exact causes of colorectal cancer are still unclear. However, researchers have found several factors that can increase a person’s risk of developing the disease.

Some risk factors are out of people’s control. These include:

  • Being older – colorectal cancer is more common after age 50.
  • A personal or family history of colorectal cancer or colorectal polyps.
  • A personal history of inflammatory bowel disease (eg. Crohn’s disease or ulcerative colitis).
  • Having a genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).
  • Having type 2 diabetes.

Lifestyle factors may also increase the risk of colorectal cancer. These include:

  • Not exercising regularly.
  • Not eating enough fruit and vegetables (especially those high in Vitamin D).
  • Eating a low-fibre and high-fat diet, or a diet high in processed meats.
  • Being overweight or obese.
  • Smoking.
  • Drinking alcohol.

The good news is that the above lifestyle factors can be adjusted to generally reduce a person’s risk and improve their overall health.

Reduce the risk

The two key steps to reducing the risk of colorectal cancer are lifestyle modification and screening.

Recommended lifestyle adjustments include; eating well, exercising regularly, quitting smoking and cutting back on alcohol.  

Preventative action is having regular screening. These screenings can help find polyps, ensuring they are removed before they turn cancerous.

People with an average risk of colon cancer are recommended to get colon cancer screening around age 50. However, those with an increased risk, such as those with a family history of colon cancer, should consider screening sooner.

Thankfully, the rate of people being diagnosed with colorectal cancer each year has dropped overall since the mid-1980s, with more people getting screened and changing their lifestyle habits.

Colorectal cancer symptoms

Colorectal cancer might not cause symptoms right away, however, people may experience:

  • A change in bowel habits.
  • Diarrhoea or constipation that lasts for more than a few days.
  • Blood in stool.
  • Feeling unrelieved after a bowel movement.
  • Cramping or abdominal (stomach) pain.
  • Fatigue.
  • Unintentional weight loss.

Because colorectal polyps (abnormal growths that can turn cancerous) don’t always cause symptoms, someone could be affected and unaware. This is why regular screening is vital.

Those experiencing the above symptoms should talk to their doctor.

Getting a diagnosis

If signs and symptoms indicate potential colon cancer, doctors may recommend one or more tests and procedures, including:

  • Colonoscopy – a scope with a video camera attached is used to examine the inside of the colon. This procedure gives doctors the opportunity to take tissue samples (biopsies) for analysis and remove polyps.
  • Blood tests – although blood tests can’t diagnose colon cancer, doctors can read your results for clues about your overall health, such as kidney and liver function tests.

Once diagnosed, a treatment plan will be created and implemented by a doctor or others in healthcare.


Research is always evolving in the area of colorectal cancer prevention and treatment. Currently, there are three main types of treatment for colorectal cancer:

  • Chemotherapy – a drug treatment that uses powerful chemicals to kill fast-growing cells.
  • Targeted therapy – works differently from chemotherapy, targeting the specific traits of cancer cells that make them different to normal cells.
  • Surgery – after chemo or targeted therapy has been used to shrink the tumour(s), surgeons are able to remove it.

With the constant evolution in research and healthcare, the overall risk of colorectal cancer is decreasing. People are encouraged to make necessary lifestyle changes and commit to regular screenings for their best chance against colorectal cancer.


American Cancer Society

Centers for Disease Control and Prevention

Mayo Clinic

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Courtney Cawte
Courtney Cawte is a freelance copywriter who connects businesses with their brand's essence and dream clients. Writing is three of her loves rolled into one - words, meeting wonderful humans and telling darn good stories. Courtney's collaborative approach results in website copy, blogs and social media content.
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