Bowel cancer
Find out about the risk factors, symptoms, screening, and when to seek advice.
Overview
How common is bowel cancer?
Bowel cancer is the second leading cause of cancer-related deaths worldwide, with more than 1.9 million new cases a year and 930,000 deaths each year. Incidence rates have been increasing in high-income countries due to effective screening programmes, as well as lifestyle and diet. More recently, rates have been increasing in middle- and low-income countries, as well as a worrying rise in those diagnosed under the age of 50 in both developed and developing countries.
Risks
Bowel cancer usually develops as a result of several different factors acting together, rather than a single cause.
Your risk may be influenced by age, family history, inherited genetic conditions, personal medical history, diet, lifestyle and ethnicity. Having one or more risk factors does not mean you will develop bowel cancer, but awareness can help guide screening and monitoring.
Key bowel cancer risks factors are outlined below:
Age
The risk of bowel cancer increases with age, particularly from around the age of of 45. The average age of diagnosis is 66.
This is why screening becomes increasingly important as people get older, even if they feel well.
Family History
Having several close relatives who have had bowel cancer can increase your risk compared with the general population. In some families, bowel cancer may be linked to inherited genetic conditions, which can lead to cancer developing at a younger age.
If bowel cancer runs in your family, it may be helpful to discuss this with a healthcare professional.
Genetics
Some inherited conditions are associated with a higher risk of bowel cancer including:
- Familial Adenomatous Polyposis (FAP)
- Li-Fraumeni Syndrome
- Cowden Syndrome
- Neurofibromatosis.
Not everyone with bowel cancer has an inherited condition, but identifying those who do can help guide screening and prevention strategies.
Personal history
Certain bowel conditions are known to increase the risk, including inflammatory bowel disease (Crohn’s Disease & Ulcerative Colitis) and conditions that cause benign polyps which can sometimes develop into cancer, over time.
People with these conditions are often offered closer monitoring.
Diet
Diet plays an important role in bowel health. Diets high in red or processed meat have been linked to a higher risk of bowel cancer, while diets rich in fruit, vegetables, whole grains, and fibre are associated with a lower risk.
Making small, sustainable changes to your diet, such as eating less red and processed meat, can benefit your bowel health and your overall wellbeing.
Lifestyle
Several lifestyle factors are associated with bowel cancer risk, including smoking, alcohol, obesity and low levels of physical activity.
A balanced diet and regular exercise are two of the best way to maintain a healthy lifestyle. Being overweight or obese is a risk factor for many cancers so reducing your weight to a healthy level is a positive step in reducing your overall cancer risk.
Race/Ethnicity
Bowel cancer is more common in non-Hispanic Black Americans, who are also more likely to be diagnosed at a younger age. People of Ashkenazi Jewish heritage also have a higher incidence of bowel cancer. Hispanics and Asian/Pacific Islanders have a lower incidence, but understanding the differences is important for everyone, to ensure timely screening and early assessment.
Symptoms
Symptoms of bowel cancer can be vague and are often very similar to non-cancerous bowel conditions, such as irritable bowel syndrome (IBS), inflammatory bowel disease, diverticular disease and infection. Symptoms may be completely absent in the early stages.
If you experience any of the possible symptoms of bowel cancer listed below, it’s important to seek medical advice.
Possible symptoms of bowel cancer include:
Blood in your stools (poop) or bleeding from your back passage
A change in your bowel habit that lasts longer than three weeks. This may include an increase in the frequency of passing stools, loosening of the stool (diarrhoea) and less commonly hardening of the stool (constipation).
Unexplained weight loss
A constant or intermittent pain in your abdomen
A lump in your abdomen that doesn’t go away
Extreme tiredness for no particular reason
A feeling that you haven’t fully emptied your bowel after going to the bathroom
As bowel cancer progresses, there may be other signs of bowel cancer to look out for. Bleeding may occur internally without visible blood in the stool, leading to anaemia. This may cause:
Breathlessness
Dizziness
Tiredness
Looking pale
If the bowel becomes obstructed, symptoms may include:
Vomiting
Bloating/distension – particularly in the area around your belly button.
Difficulty passing a stool, or difficulty passing gas
Be Bowel Aware
How to reduce your risk of bowel cancer
A number of changes to your lifestyle can significantly reduce your risk of bowel cancer including:
Eating less red or processed meat
Eating a healthy balanced diet that includes fruits, vegetables, whole grains and fibre
Reducing your weight if overweight or obese
Reducing your alcohol intake
Stopping smoking
Having regular bowel cancer screening from age 45+
Reduce risk
Some risk factors for bowel cancer are outside of your control, but steps that may reduce your risk include:
Eating less red or processed meat
Eating a healthy balanced diet rich in fruit, vegetable, whole grains and fibre
Maintaining a healthy weight
Reducing alcohol intake
Stopping smoking
Having regular bowel cancer screening
Be Bowel Aware
Are you showing any signs of these common symptoms of suspected bowel cancer?
Blood in your stools or bleeding from your bottom
A change in your bowel habit that lasts for more than 3 weeks
Unexplained weight loss
A constant or intermittent pain in your tummy
A lump in your tummy that doesn't go away
A feeling that you haven't fully emptied your back passage after going to the toilet
Extreme tiredness
Blood in your stools or bleeding from your bottom
A change in your bowel habit that lasts for more than 3 weeks
Unexplained weight loss
A constant or intermittent pain in your tummy
A lump in your tummy that doesn't go away
A feeling that you haven't fully emptied your back passage after going to the toilet
Extreme tiredness
Getting tested
Screening
Bowel cancer screening aims to detect cancer early, before symptoms develop. Screening can also identify non-cancerous lesions (polyps) that may later turn into cancer, allowing them to be removed and reducing the risk of bowel cancer forming.
Screening options may include stool-based tests or a colonoscopy. You should discuss the most appropriate screening options with your health care provider and insurer.
Screening often starts with a quantitative Faecal Immunochemical Test (qFIT), which detects tiny amounts of blood in your stool. If blood is detected, further tests such as a colonoscopy (an examination of the entire large bowel using a flexible camera) or a CT colonoscopy, also known as virtual colonoscopy may be recommended.
How bowel cancer screening is evolving
Around 10% of bowel cancer cases are now thought to be linked to inherited genetic causes, most commonly Lynch syndrome. People with Lynch syndrome are at increased risk of several cancers, including bowel and endometrial cancer, but can now be identified through molecular pathology testing and offered tailored screening and prevention strategies.
Research has also shown that simple interventions can make a significant difference. For example, studies suggest that low-dose aspirin may substantially reduce cancer risk in people with Lynch syndrome, offering an effective prevention strategy for some individuals.
Screening and monitoring methods continue to improve. In addition to FIT testing and colonoscopy, newer tools such as stool DNA testing (e.g. Cologuard) and blood-based tests designed to detect minimal residual disease are being developed to help identify new or recurrent bowel cancers earlier.
Clinical insight provided by Professor Andrew Beggs, Professor of Cancer Genetics and Colorectal Surgery.
If you have symptoms
If you have symptoms suggestive of bowel cancer, it is important to tell your healthcare provider and seek medical advice, even if they feel mild or come and go. Initial tests will often include a quantitative Faecal Immunochemical Test (qFIT). Depending on results and symptoms, further investigations such as colonoscopy or CT colonography may be recommended, even if initial tests are normal.
Remember, finding bowel cancer early can make treatment more effective and improve long-term outcomes.