Bowel Cancer Prevention

Introduction

Bowel cancer (or colorectal cancer) refers to cancer that develops in the large bowel (colon and rectum; see figure 1). The large bowel is a part of the digestive system. Specifically, it helps our bodies absorb water from food and eliminates waste. Cancer is the abnormal or uncontrollable growth and division of cells. It can cause tumours to form and, in some cases, can spread to other organs.

Bowel cancer is the second most common form of cancer worldwide. In 2020, there were an estimated 1.9 million new cases of bowel cancer reported, which caused over 930,000 deaths. By 2040, it is projected that there will be 3.2 million new cases (a 63% increase) and 1.6 million deaths (a 73% increase) annually.¹ In high-income countries, the incidence rates of colorectal cancer have been declining, primarily due to the success of effective screening programs.

In the UK, 120 people are diagnosed with bowel cancer every day - and this number is expected to increase to 130 by 2040. Bowel cancer is the fourth most common cancer in the country, with rectal cancer being more prevalent than colon cancer.

Bowel cancer statistics show that 1 in 15 men and 1 in 18 women will be diagnosed with bowel cancer at some point in their lifetime. The vast majority of bowel cancer cases (94%) happen in people aged 50 and above. However, bowel cancer can affect anyone of any age, and we have observed a trend in the past few years where more and more cases are being identified in people below 50 years old, with 2,600 new cases being diagnosed each year.

Symptoms

Even though bowel cancer is common, the encouraging news is that it can be prevented. Approximately 8 in 10 people survive bowel cancer for one year or more after treatment. Nearly 6 in 10 people survive bowel cancer for five years or more, and more than 5 in 10 people survive it for 10 years or more. By learning about the risk factors, making healthy lifestyle choices, and using available screening methods, people can greatly lower their chances of getting this potentially fatal disease.

The symptoms of bowel cancer include:²

• Bleeding from your bottom
• Blood in your stools
• A change in your bowel habits
  • going more often
  • going less often 
  • having diarrhoea 
  • having constipation
• Unexplained weight loss and/or tiredness
• A lump in your stomach
• Stomach pain

Having these symptoms doesn’t necessarily mean you have bowel cancer. On the other hand, if you have bowel cancer, you may only experience one or two of these symptoms. If you are concerned it is highly advisable to see your GP.

Risk factors

Recognising the risk factors for bowel cancer is crucial for its prevention. While some factors, such as age and genetic susceptibility, are not under our control, some lifestyle changes can help prevent or delay its development. 

Risk factors for bowel cancer include:

Age

The risk of bowel cancer increases considerably after the age of 50. This is because older people have had longer and greater exposure to carcinogens (substances that have the potential to cause cancer), but also because the longer we live, the more cell divisions happen in our body. This increases the likelihood of genetic mutations, which if accumulated in a high number, can lead to the development of cancerous cells. 

Other changes in our body that happen with age may also increase the chance of developing cancer. These include having a weaker immune system, chronic inflammation, and the development of pre-cancerous polyps (small growths in the lining of the large bowel).

Family history 

Some individuals inherit specific genetic mutations that cause them to be predisposed to an increased risk of bowel cancer. Early onset of bowel cancer is more likely to be associated with inherited genetic factors.

Diet 

Some foods have components that may have carcinogenic effects and/or lead to chronic inflammation. These include: 

• Red meat (beef, lamb or pork) 
• Processed meats (sausages, bacon and ham)
• Fat-rich foods 
• Foods low in fibre
• Excessive alcohol consumption

Physical inactivity 

People with a sedentary lifestyle have higher risk of bowel cancer. 

Physical activity helps with digestion and transit, reducing the time that potential carcinogens are in contact with the lining of the colon.³

Physical activity also improves chronic inflammation and the body’s ability to fight cancerous cells. In addition, exercise helps regulate hormone levels, such as insulin, which is associated to colorectal cancer.³

High BMI (body mass index) 

Maintaining a healthy weight reduces the risk of colorectal cancer. 

Excess body fat, particularly around the abdomen, is associated with an increased risk of cancer due to higher levels of inflammatory markers and insulin resistance.

Smoking 

Long-term smokers are more likely to develop an array of diseases, including bowel cancer.

Tobacco smoke contains several carcinogenic substances that may: 

• Cause changes in the gut environment
• Increase the development of polyps 
• Increase the chances of chronic inflammation
• Weaken the immune system
• Potentiate the malignant effects of other lifestyle risk factors such as
  • alcohol use 
  • lack of physical exercise 
  • an unhealthy diet

Inflammatory bowel disease (IBD) 

Certain conditions such as Crohn's disease and ulcerative colitis increase your risk of bowel cancer. Both of these diseases cause chronic bowel inflammation, which can increase the likelihood that cells become cancerous. There is also a higher cell turnover in an attempt to repair the damage in the lining of the bowel, increasing the chances of cancer-inducing mutations.

Prevention

Diet

Diet plays a critical role in the prevention of bowel cancer. By changing some of our daily choices, we can decrease the chances of developing the disease. 

The table below shows foods that can help prevent bowel cancer and foods that should be limited in our diet.

Physical activity

Regular physical activity is another vital measure in preventing bowel cancer. 

Exercise helps reduce abdominal fat, aids the digestive system and reduces inflammation. The World Health Organisation recommends 150-300 minutes of moderate-intensity aerobic exercise or 75-150 minutes of vigorous-intensity aerobic exercise per week. Aerobic, or cardio exercise, is repetitive and structured and uses oxygen to produce energy. Examples include brisk walking, cycling and swimming.³

Smoking and alcohol

Smoking and excessive alcohol consumption are significant risk factors for bowel cancer. Reducing these habits can greatly reduce the risk. 

Smoking is associated with several types of cancer and bowel cancer is not an exception. Smoking cessation produces immediate health gains even for long-term smokers.

Restricting alcohol consumption is fundamental. Although stopping would be the ideal goal, reducing to moderate levels can already produce great benefits. 

The UK Department of Health advises limiting alcohol consumption to a maximum of 14 units per week over at least 3 days. This corresponds to about 6 medium (175ml) glasses of wine or 6 pints of 4% beer.⁴ While no amount of alcohol is risk-free, adhering to these guidelines can improve your health significantly. You can check if your drinking habits are within the recommended amount here.

Routine screening

Screening is one of the main measures for bowel cancer prevention. Regular screenings can detect the presence of cancerous or precancerous cells, leading to timely intervention and better outcomes.

Screening methods for bowel cancer are described below:

• Faecal Immunochemical Test (FIT)
  • In England, if you are between 54 and 74 years old, you will be invited to participate in bowel cancer screening every two years⁵ 
  • The screening age is gradually being extended to include those aged 50-53, so you might receive a test before turning 54
  • The FIT is a non-invasive test that is typically sent home to you
  • It detects hidden blood in the stool, which can be an early sign of bowel cancer
  • If the test is positive, your doctor will recommend further tests

• Colonoscopy
  • This is the most effective screening method for detecting bowel cancer and will be suggested if you have any symptoms
  • It involves examining the entire colon and rectum using a flexible tube with a camera
  • Simple polyps found during the procedure can be removed at the same time
  • Colonoscopies are done with medication that makes you relaxed and helps with pain to ensure you are comfortable throughout the entire process

• Flexible sigmoidoscopy
  • A flexible sigmoidoscopy is similar to a colonoscopy but less invasive
  • It examines the inside of the rectum and the lower part of the colon (sigmoid), where most bowel cancers start

• CT colonography
  • Also called a virtual colonoscopy, this imaging test uses advanced computer software and technology to create detailed images of the colon and rectum
  • A tube is inserted in your rectum and colon
  • The tube is much smaller than the one used in colonoscopies, therefore it does not require relaxing medication
  • Although it is less invasive, a follow-up colonoscopy may be necessary if any abnormalities are detected

Genetic testing

For people with a family history of bowel cancer, genetic counselling and testing can be beneficial. 

Certain inherited conditions, such as Lynch syndrome and familial adenomatous polyposis (FAP), considerably increase the risk of bowel cancer. People at an increased risk of bowel cancer may need more frequent and earlier screenings. 

If you have a family history of bowel cancer, your GP is the best person to advise you and direct you to the right specialist services.

Summary

• Early detection is vital in combating bowel cancer, as early treatment is highly successful
• People over 50 years old or with a family history of bowel cancer should have routine screenings. Please see your GP for further advice
• Lifestyle factors play a big role in bowel cancer prevention. A diet high in fruits, vegetables, and whole grains, combined with reducing red and processed meat intake can significantly lower the risk
• Regular physical exercise and cutting back on smoking and alcohol consumption are also measures that can have a positive impact on gut health