Bowel cancer is one of the most common types of cancer that affects adults. It is also a leading cause of cancer deaths worldwide, although advancements in treatment methods have allowed people to generally see better outcomes with early diagnosis and treatment. This, however, makes recognising bowel cancer symptoms and risk factors all the more important.
Since bowel cancer starts in the large intestine, it mainly causes bowel symptoms such as changes to the stool, and changes to the ease or frequency of defecating.
Some of the bowel cancer symptoms can actually be intermittent, they come and go. Examples include abdominal pain and rectal bleeding. People who experience intermittent symptoms may not think that they are serious and may delay getting treatment.
To help you better identify if you have symptoms of bowel cancer or just common bowel symptoms, we will explain the other accompanying symptoms that you might observe if you have bowel cancer, who is at higher risk for bowel cancer, and what you should do to prevent or treat bowel cancer.
All about bowel cancer
Bowel cancer, also known as colorectal cancer, is a cancer that begins in the colon or rectum.
What is the cause of bowel cancer?
Just like any other cancers, bowel cancer starts with cells that have abnormalities in their genetic material and multiply uncontrollably.
Most of the bowel cancer cases (>90%) are of adenocarcinoma type, which begins with the uncontrollable division of glandular cells, or cells that secrete mucus, in the large intestine.1 This leads to the formation of adenomatous polyps in the large intestine, which are benign masses of cells in the lining of the large intestine. Adenomatous polyps can keep growing and turn into malignant tumours that go on to cause bowel cancer.
There are other types of bowel cancer depending on which tissue type is affected first in the large intestine.
As bowel cancer progresses, some cancer cells in the large intestine may get transported through the blood and lymphatic system to other sites where they form a secondary tumour. This process is known as metastasis and it means that the cancer has ‘spread’. This usually happens at the later stages of bowel cancer, which makes treating it even more challenging.
Signs And Symptoms
Here are some of the most common symptoms that people with bowel cancer experience:2
- Rectal bleeding
- Abdominal pain
- Persistent changes in bowel habits, such as increased frequency of defecation and looser stools
- Weight loss
- Constipation
- Diarrhoea
At first, people with bowel cancer normally do not show any symptoms. When symptoms do appear, it could be due to a tumour growing into the lumen of the large intestine.
People can sometimes have these symptoms without having bowel cancer, meaning these symptoms are not specifically indicative of bowel cancer.
Can symptoms of bowel cancer come and go
Some people may experience symptoms that come and go, and therefore not take much notice of them. However, these symptoms are not less dangerous and you should not dismiss their potential link with bowel cancer. For example, abdominal pain in bowel cancer may initially come and go if it is due to stool not being able to pass from the bowel.
According to Dr Alfred Neugut, rectal bleeding can also be intermittent, which can lead to it being ignored. If you have this symptom, you may spot blood in your stool. The blood comes from bleeding polyps in the large intestine, and larger polyps tend to have higher chances of bleeding. The blood can be bright or dark red and can make your stool appear dark.
Who usually gets bowel cancer?
There are both genetic and environmental factors that cause a person to have a higher chance of developing bowel cancer than others. While genetic factors are not something you can change, you can take sensible steps to reduce your risks for bowel cancer by avoiding certain environmental risk factors.
Family history
If someone from your family has bowel cancer, especially your immediate family members, you may have a higher risk for bowel cancer. This is because there are genetic mutations that predispose a person to higher bowel cancer risk, and these genetic mutations can be inherited. Family history also increases the risk for early-onset bowel cancer.3
Predisposing health conditions
Some health conditions are known to elevate the risk for bowel cancer. These include:
- Obesity
- Diabetes
- Inflammatory bowel syndrome (IBS)
- History of adenomatous polyps
Age
People aged 50 or above usually have a higher risk of getting bowel cancer compared to people below 50. However, in recent years there has been an increase in the number of people younger than 50 years old getting bowel cancer.4
It is recommended that people aged 50 and above get screened for bowel cancer so that polyps that could potentially turn malignant can be detected early and removed. If you live in the UK, the NHS has a bowel cancer screening programme for people aged 60 - 74 and is gradually expanding to include the 50 - 59 age group. People of this age group will be sent a home test kit every 2 years to collect stool samples for testing if they are registered with a GP.
Sex
Males have an almost 50% higher risk of developing bowel cancer compared to females, especially individuals of age 50 and above. Males also have a higher mortality rate for bowel cancer compared to females.5
Lifestyle
Diets high in fats, sugar, and red meat are known to increase the risk for bowel cancer. Many people also do not exercise regularly, which is also associated with a higher risk of obesity and bowel cancer.4
When to consult a doctor
According to the NHS, you should seek medical advice if you experience bowel cancer symptoms for 3 weeks or more. If your doctor suspects you have bowel cancer, they may carry out physical examinations and recommend screening with a colonoscopy or a CT colonography. Doctors may also take a sample of tissue through biopsy, often during a colonoscopy, to test if it contains cancer cells.
Treatment and prevention of bowel cancer
The type of treatment used may differ based on the stage of the cancer and whether the cancer is localised in the bowel or has spread. Treatment for bowel cancer includes:
- Surgery - removal of the polyps or tumour
- Radiotherapy - uses radiation to kill cancer cells or shrink a tumour for easy removal
- Chemotherapy - uses drugs to kill cancer cells
- Immunotherapy - triggers the immune system to destroy the cancer cells
- Targeted drug therapy - uses drugs that target the aberrant pathways that help cancer cells survive and grow
Some people may require a combination of these cancer treatments depending on the stage of their cancer. These treatments also come with side effects, so make sure to discuss your treatment plan with your doctor.
For people with a higher risk for bowel cancer, such as people with a family history, you can prevent it by screening for and removing the pre-cancerous polyps if you have them. Pre-cancerous polyps have the potential to cause cancer, and the earlier they are discovered and removed, the better.
Summary
Bowel cancer is one of the most common cancers that affect adults worldwide. Some of the symptoms that people may experience include abdominal pain, change in bowel habits, rectal bleeding, weight loss, diarrhoea, and constipation. You may experience abdominal pain and rectal bleeding that comes and goes if you have bowel cancer, so do not ignore these symptoms and seek medical advice from your GP as soon as you can. Screening is highly recommended for preventing and detecting bowel cancer at its early stages, especially for people aged 50 and above. Besides that, adhering to a healthy lifestyle is also important in reducing the risk of bowel cancer.
References
- Fleming M, Ravula S, Tatishchev SF, Wang HL. Colorectal carcinoma: Pathologic aspects. Journal of Gastrointestinal Oncology [Internet]. 2012;3(3):153–73. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3418538/
- Adelstein BA, Macaskill P, Chan SF, Katelaris PH, Irwig L. Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a systematic review. BMC Gastroenterol [Internet]. 2011 May 30 [cited 2022 Oct 24];11(1):65. Available from: https://doi.org/10.1186/1471-230X-11-65
- de la Chapelle A. Genetic predisposition to colorectal cancer. Nat Rev Cancer [Internet]. 2004 Oct [cited 2022 Oct 29];4(10):769–80. Available from: https://www.nature.com/articles/nrc1453
- Wong MCS, Huang J, Lok V, Wang J, Fung F, Ding H, et al. Differences in incidence and mortality trends of colorectal cancer worldwide based on sex, age, and anatomic location. Clinical Gastroenterology and Hepatology [Internet]. 2021 May 1 [cited 2022 Oct 28];19(5):955-966.e61. Available from: https://www.sciencedirect.com/science/article/pii/S1542356520301968
- Abancens M, Bustos V, Harvey H, McBryan J, Harvey BJ. Sexual dimorphism in colon cancer. Frontiers in Oncology [Internet]. 2020 [cited 2022 Oct 29];10. Available from: https://www.frontiersin.org/articles/10.3389/fonc.2020.607909