Bowel cancer, sometimes called colorectal cancer is one of the most common cancers in Australia. Early detection saves lives, but many people don’t recognise the early warning signs or understand their personal risk factors. This guide explains:
What bowel cancer is
Who’s at risk
Common and less common symptoms
It’s important to be aware of the symptoms of bowel cancer to ensure early detection and treatment.
When to see a doctor
How bowel cancer is diagnosed
What to do next
This article is designed to empower you with clear, evidence-based information written for patients and families.
What Is Bowel Cancer?
Bowel cancer refers to cancer that begins in the large intestine, which includes the colon and rectum. It generally starts as a small growth called a polyp that can develop into cancer over years.
According to Cancer Council Australia, colorectal cancer is one of the most commonly diagnosed cancers in Australia. Early stages may not cause symptoms, which is why understanding risk factors and regular screening is so critical.¹
“Bowel cancer” and “colorectal cancer” are often used interchangeably.
Understanding Risk Factors
You can’t change some risk factors, but being aware helps with early detection and prevention strategies.
Non-modifiable Risk Factors
These are factors you cannot change:
Age: Most cases occur in adults over 50.²
Family history: Having a close relative with bowel cancer increases risk.
Personal history: Prior bowel polyps or inflammatory bowel disease (Crohn’s disease, ulcerative colitis).
Genetic syndromes: Conditions like Lynch syndrome or familial adenomatous polyposis (FAP).³
Modifiable Risk Factors
These are lifestyle or environmental factors you can influence:
Diet: Low fibre diets high in red or processed meats.⁴
Physical inactivity: Regular exercise reduces risk.
Smoking: Tobacco use increases cancer risk in multiple organs.
Alcohol: Heavy drinking is associated with higher colorectal cancer rates.
Obesity: Linked to increased risk in both men and women.
By addressing lifestyle risks, you may reduce your overall risk or improve general health.
Common Signs and Symptoms of Bowel Cancer
Bowel cancer can progress silently, so symptoms can be subtle, especially in early stages. However, the most recognised warning signs include:
1. Changes in Bowel Habits
Persistent diarrhoea or constipation
Feeling like your bowel does not empty completely
Narrower stools than usual
These don’t always signal cancer, but if changes persist for more than four weeks, seek medical advice.
2. Blood in Stools
This may appear as:
Bright red blood on toilet paper or in the bowl
Dark, tarry stools (indicating digested blood)
Not all bleeding is due to cancer. Haemorrhoids and anal fissures can also cause bleeding, but any unexplained or recurrent bleeding should be evaluated.
3. Abdominal Pain or Discomfort
Persistent or unexplained:
Cramps
Bloating
Gas pains
General discomfort
Pain that doesn’t resolve over time warrants investigation.
4. Unexplained Weight Loss
Rapid weight loss without diet or exercise changes can be a red flag for many cancers, including bowel cancer.
5. Fatigue and Weakness
Chronic tiredness or weakness can occur due to ongoing bleeding and resulting iron-deficiency anaemia.
6. Symptoms of Anaemia
Pale skin
Shortness of breath
Heart palpitations
These can be consequences of slow blood loss in the gut.
Less Common or Subtle Signs
Even if symptoms don’t seem obvious, pay attention to combinations of signs:
Rectal discomfort or tenesmus (feeling of needing to pass stool even after the bowel is empty)
Persistent gas and bloating
Unexplained nausea or vomiting
Many early symptoms mirror benign digestive issues, but persistence and change from your normal baseline are key flags.
When Should You See a Doctor?
You should make an appointment if you experience:
- Persistent change in bowel habits
- Blood in your stool
- Unintended weight loss
- Chronic abdominal discomfort
- Signs of anaemia
Urgent Medical Review
Seek prompt (within days) evaluation if you have:
Heavy bleeding
Severe abdominal pain
Dizziness or fainting
Signs of bowel obstruction (severe bloating, inability to pass gas/stool)
How Bowel Cancer Is Diagnosed
Your doctor may recommend one or more of the following:
1. Faecal Occult Blood Test (FOBT) / FIT
A simple stool test that detects hidden blood. Regular screening using the Faecal Immunochemical Test (FIT) can detect early cancers and precancerous changes. The Australian Government’s National Bowel Cancer Screening Program sends FIT kits to eligible adults aged 50–74.⁵
2. Colonoscopy
This is the gold standard for diagnosis.
During a colonoscopy:
A flexible camera examines the entire colon
Polyps can be removed during the procedure
Tissue samples (biopsies) can be taken
Colonoscopy provides both diagnosis and prevention by removing polyps before they become cancerous.
3. Imaging Studies
CT Colonography (virtual colonoscopy)
MRI or CT scans for staging
4. Blood Tests
Blood work may include:
Full blood count (for anaemia)
Tumour markers (such as CEA), not diagnostic but useful in some cases
How Staging Works (Why It Matters)
Once cancer is found, it’s staged from I to IV, indicating:
How deep it has grown into the bowel wall
Whether it has spread to lymph nodes or distant organs
Early stages (I-II) have significantly better outcomes when treated promptly.
Screening and Prevention: What You Can Do
National Bowel Cancer Screening Program
Eligible Australians aged 50–74 receive a free FIT testing kit every two years.⁵
Even if you’re asymptomatic, participating in screening can save lives.
Lifestyle Strategies to Reduce Risk
Eat a diet high in fruits, vegetables and whole grains
Limit red and processed meats
Maintain a healthy weight
Exercise regularly
Reduce alcohol intake
Avoid smoking
While lifestyle changes can’t eliminate risk entirely, they improve overall health and may reduce the likelihood of cancer development.
Frequently Asked Questions
Is blood in stool always cancer?
No. Many conditions (haemorrhoids, anal fissures, infections) can cause bleeding. Still, unexplained or ongoing bleeding should always be investigated.
Do I need a colonoscopy if I feel fine?
If you are within the screening age (50+), have a family history, or have abnormal FIT results, yes — early colonoscopy is recommended.
Can bowel cancer be prevented?
Not all cases are preventable, but early detection and lifestyle changes significantly reduce risk and improve outcomes.
Conclusion
Bowel cancer doesn’t always announce itself loudly and that’s why understanding risk factors, knowing the signs, and participating in recommended screening programs are so important.
If you notice persistent changes in your bowel habits, blood in your stools, unexplained weight loss, or ongoing abdominal discomfort, don’t wait, book an appointment with your doctor or an experienced gastroenterologist at Direct Endoscopy.
Concerned About Your Symptoms? Speak With a Specialist
If you have noticed persistent changes in your bowel habits, blood in your stool, ongoing abdominal discomfort, or unexplained fatigue, it is important not to delay medical advice.
At Direct Endoscopy, our experienced gastroenterology team provides thorough assessment and evidence-based care for patients experiencing bowel symptoms. We offer:
Comprehensive bowel cancer screening
Colonoscopy with polyp removal where required
Investigation of unexplained gastrointestinal symptoms
Personalised follow-up care and management
Early detection significantly improves treatment outcomes. Even if your symptoms seem mild, professional evaluation provides clarity and peace of mind.
If you are concerned about your risk of bowel cancer or have received a positive screening test, contact Direct Endoscopy to arrange a consultation with our team.
References
- Cancer Council Australia – Bowel cancer statistics and information
- Cancer Australia – Colorectal cancer risk factors and screening
- CDC – Colorectal Cancer and Lynch Syndrome
- World Cancer Research Fund – Diet, nutrition and colorectal cancer
- Australian Government – National Bowel Cancer Screening Program