Bowel cancer, also known as colorectal cancer, is a general term referring to the development of abnormal cell growth in parts of the large intestine. It can occur either in the colon or the rectum.
According to NHS figures, one in 20 people will develop bowel cancer in their lifetime, with around 40,000 people being diagnosed per year in the UK. This makes bowel cancer one of the most common forms of cancer.
Symptoms
The symptoms of bowel cancer may vary depending on the tumour’s location, and whether it has spread to other parts of the body or not.
The main symptoms are blood in your stool, abdominal pain, weight loss and abnormal bowel functioning (such as incontinence, more frequent stools and diarrhoea). [94]
These symptoms can easily be misdiagnosed however, as they are commonly seen in older people who do not have bowel cancer. Blood in the stool is most commonly caused by haemorrhoids, and the changes in bowel functioning can be the result of an inconsistent, unhealthy diet.
Cause
Our bodies are made up of a variety of cells that have different functions. Put simply, cancer is the result of abnormal, uncontrolled cell division. Cell division (mitosis) occurs as the result of a parent cell creating two new identical cells that will take its place, carrying on their specific function.
The nucleus is the portion of a cell which contains genetic information in the form of DNA (Deoxyribonucleic acid). This information controls instructions on how and when mitosis should occur. DNA in the cells can become mutated, and whenever this occurs, the mutated cell can be instructed to reproduce various defective copies of itself. Because it can override the chemical signals telling the cells to stop dividing, it may result in a large cluster of defective cells known as a tumor.
Generally, bowel cancer originates as clusters of cells that develop on the inner epithelial cells, which line the inside of the intestine. These small lumps are known as polyps. Having polyps doesn’t mean you will get bowel cancer, but it is a common risk factor. [95] [96]
Other risk factors for bowel cancer include:
- Age: the likelihood of developing bowel cancer increases dramatically as you age. 90 per cent of people with bowel cancer are over 50 years old. [97]
- Family history: having a close relative with bowel cancer increases the likelihood that you will develop it.
- Smoking: long-term smokers of cigarettes have been shown to be at greater risk of developing bowel cancer. [98] [99]
- Alcohol: consumption of alcohol has been linked to various types of cancer, including bowel cancer. [100]
- Diet: not eating enough fruit or vegetables has been linked to an increased risk of developing bowel cancer. [101]
Prevention
Although some of the factors that increase the risk of bowel cancer – such as genetic predisposition or age – can’t be changed, focusing on changing your lifestyle can have a massive effect. Around half of all bowel cancer cases are attributed to lifestyle factors, with a quarter of these thought to be preventable. [102]
Diet
A wealth of research has shown that diet and bowel cancer are closely linked. Your focus should be on general healthy eating, with the majority of your carbohydrates coming from whole grains (such as brown rice, quinoa, brown bread and brown pasta), while reducing consumption of their white counterparts. Whole grains also contain plenty of fibre, which has been shown to reduce the risk of bowel cancer. [103]
Cutting down on your alcohol consumption has been shown to decrease the risk of bowel cancer development.
It is also advised to eat less processed and red meat, as they are thought to be related to bowl cancer. [104] The NHS advises anyone eating over 90 grams of red meat per day to cut back to around 70 grams. Red meat includes beef, lamb, pork, veal, venison and goat. Processed meats refer to bacon, salami, sausage, hot dogs, processed deli meats and luncheon meat. The World Cancer Research Fund recommends completely cutting out processed meats.
It is also advised to eat fruit and vegetables in abundance. Research has shown that a lack of fruit and vegetables increases the risk of developing bowel cancer. [105] The NHS advises you eat five portions of fruit and vegetables per day, although other research suggests that six or seven portions may be needed.
Exercise
Frequent physical activity has been shown to decrease the likelihood of bowel cancer, making it an important preventative tool. [106] Around 150 minutes of relatively vigorous exercise should be completed per week. This can be completed in the form of running, cycling, power walking, swimming, resistance training, dancing or through sports like football, basketball or rugby.
It is also extremely important to quit smoking, as this can massively reduce your risk of developing bowel cancer. [106]
