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Bowel cancer

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 5 minutes read

Cancer occurs when cells in our body multiply out of control, producing lots of abnormal cells. These abnormal cells don't function like they should and can invade tissues or organs and sometimes spread to other parts of the body.

Bowel cancer, also known as colorectal cancer, includes cancer of the colon (which is the large intestine) and cancer of the rectum (which is the last few inches of the large intestine before it turns into the anus).

It is the third most common cancer in the US, affecting both men and women, and is more likely as we age. Certain genetic and lifestyle factors can increase your risk - we'll talk you through them.

Symptoms of bowel cancer include blood in the stool, a change in your bowel habits for more than a few weeks, and a tending towards diarrhea, but may also tend towards constipation, too. Another symptom may be abdominal pain or discomfort and bloating.

It is important to note that most people with these symptoms do not have bowel cancer, but if they persist, occur with older individuals, or occur with symptoms like loss of appetite, fatigue, and unintentional weight loss - this should be discussed with a doctor urgently.

The Centers for Disease Control and Prevention (CDC) recommends that all adults aged 45-75 years be screened for colorectal cancer. Your doctor may recommend earlier testing if you are at higher risk. Results from this initial test will determine how often you should be rescreened.

Evidence shows you can reduce the risk of developing bowel cancer by eating a high-fiber diet with lots of fruit and vegetables and avoiding processed foods. You should avoid smoking and excessive alcohol intake to lower risk, and keep fit and maintain a healthy weight.

What causes bowel cancer?

The exact cause of bowel cancer is unknown, but we do know things that increase your risk of developing bowel cancer. Some factors you have control over, and others you have no control over.

The things you can't change:

  • age - the risk increases as you get older, but careful attention should still be noted in younger patients with worrying or persistent symptoms.
  • family history - if someone in your family had bowel cancer, especially under 50, that significantly increases your risk. You should talk to your doctor about screening options available to you. Polyps in the colon may run in families and can increase the risk of bowel cancer.
  • some medical issues like inflammatory bowel disease (IBD), including Crohn's and ulcerative colitis (UC), increases your chances, especially if you've been diagnosed for more than a decade.

The things you can change:

  • poor diet - switching to a high-fiber diet that's low in processed foods and low in red meat consumption is advised.
  • being overweight or obese - reducing your weight to a healthy range will reduce your chance of developing bowel cancer.
  • inactivity - increase your activity levels, aiming for at least 30 minutes of moderate activity daily.
  • alcohol and smoking - aim to reduce or stop these as either will increase your risk of bowel cancer.

When should I see my doctor?

If you have any symptoms of concern that persist for more than 3 weeks, you should see your doctor. This includes an unexplained change in bowel habits, persistent abdominal pain or bloating, blood in your stool, or unexplained fatigue or weight loss. If you have other risk factors or family history, discuss these with your doctor, as they may consider early testing.

What will my doctor do?

Your doctor will ask questions about your symptoms, relevant medical conditions, and medications, and whether any of your family has suffered bowel problems or cancer. They will feel your tummy, and they may suggest examining your rectum. They may measure your weight so they can monitor it.

They will arrange for blood tests, looking for iron deficiency anemia, as this can indicate if there is any bleeding. If you are low risk, they may ask you to do a stool sample looking for blood. They will refer you urgently for colorectal testing if you are at high risk.

How is it treated?

Bowel cancer has to be thoroughly investigated by specialists first to decide on the location of the disease and the severity (whether it has spread).

There are many ways of treating cancer, and which is chosen will depend on the area it is in, the cancer stage, and the patient’s choice and wishes. Options include surgery (where a surgeon cuts out all or part of the cancer), chemotherapy (strong medication that aims to kill cancer cells and stop them from multiplying), and radiotherapy (where radiation is targeted at the cancer cells to kill them).

Treatment could be one or a combination of these, and the aim may be to cure the cancer or to improve quality of life by shrinking the tumor to improve symptoms. Surgery alone can be very effective for cancer that has not spread and remains within the bowel.

Everyone always wants to know what their chances of surviving any cancer will be. Bear in mind that bowel cancer is much more common in the elderly, who may have other serious medical conditions. Survival rates depend on how early the cancer is diagnosed and whether it has spread to other body parts.

Related topics

Read about: Bowel cancer screening

Read about: Colonoscopy

Read about: Anal cancer

Read more about: Cancer

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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