Colon cancer often begins quietly. The first signs are usually persistent changes in bowel habits, blood in the stool, or unexplained weight loss. If these symptoms last for more than a few weeks, it’s important to see a doctor for screening. Early detection saves lives.
Symptoms such as constipation, diarrhoea, and abdominal discomfort can all indicate colorectal cancer. However, they may also result from conditions like Crohn’s disease, irritable bowel syndrome, or even a temporary gastrointestinal infection.
So, how can you distinguish whether it’s colon cancer or some other disease, and when should you consult a doctor? This blog covers how to spot the early warning signs, what diagnosis involves, and when it’s urgent to call your GP or A&E.
What are the Early Signs for Colon Cancer?
One prevalent symptom of bowel cancer is a persistent change in your bowel habits, meaning that you consistently have bowel movements more or less often than what is usual for you. (See NHS guidance here).
Additional frequent bowel cancer signs consist of:
1. Changes in Bowel Habits
Persistent changes in bowel movements, such as diarrhoea, constipation, or a sudden alteration in stool consistency, can be an early indicator of colon cancer. If these changes persist for more than a few weeks, they should be taken seriously.
2. Blood in the Stool
Blood in the stool is a significant warning sign. It may appear as bright red blood or cause stools to look dark and tarry. While haemorrhoids and other benign conditions can also cause rectal bleeding, persistent or unexplained bleeding should always be considered by a doctor.
3. Unexplained Weight Loss
Significant and unexplained weight loss can indicate an underlying health issue, including colon cancer. When the body is fighting cancer, it may use more energy, leading to weight loss without changes in diet or physical activity.
4. Persistent Abdominal Discomfort
Cramping, bloating, gas, or pain in the abdominal region that does not go away may signal a deeper problem. While occasional digestive discomfort is common, persistent symptoms should be taken seriously.
5. Fatigue and Weakness
Colon cancer can cause chronic fatigue and weakness due to internal bleeding, leading to anaemia. Low iron levels can result in extreme tiredness, dizziness, and shortness of breath.
6. Presence of a Lump in the Abdomen or Back Passage
In some cases, colon cancer may cause a lump in the abdomen or rectal area. If a lump is felt, medical attention should be sought immediately.
7. Anaemia and Tiredness
Internal bleeding caused by colon cancer can lead to iron deficiency anaemia, which results in chronic tiredness and weakness. Unexplained fatigue that persists over time should be investigated.
8. Mucus in Stools
The presence of mucus in stools can be another warning sign of colon cancer. Mucus is a jelly-like substance that helps lubricate the intestines, but an excessive amount or noticeable mucus in bowel movements may indicate inflammation, infection, or a more serious underlying condition like colon cancer.
9. Regular Pain and Bloating
Frequent pain and bloating in the stomach area, especially after eating or before passing a stool, may be an indication of an underlying problem in the digestive system. If this happens often and there is no clear reason, you should see a doctor.
10. A Feeling of Incomplete Bowel Movements
Some people with colon cancer experience a sensation that their bowel has not completely emptied after a bowel movement. This feeling of incomplete evacuation can persist even after using the washroom multiple times.
These symptoms do not automatically indicate that you have bowel cancer, as they may also result from other, less severe issues. However, if you’re worried and your symptoms are unexplained by any other factors or persist, it’s advisable to consult with your GP or another doctor.
How is Bowel Cancer Diagnosed?
Colon cancer is diagnosed through a variety of physical exams, blood tests, imaging scans, tissue samples, and other specialised tests. Below are the key diagnostic methods used:
Physical Exams
- A physical exam may include a rectal exam to check for abnormalities.
Blood Tests
- Blood tests can help assess anaemia and liver function or detect tumour traits.
- A Carcinoembryonic Antigen (CEA) test or an Immunochemical Faecal Occult Blood Test (iFOBT) can identify the presence of blood in the stool.
Imaging Scans
- CT scans, MRI scans, or ultrasound scans are used to create detailed images of the bowel.
- A PET-CT scan can provide images of the entire body to determine if the cancer has spread.
Tissue Samples
- A biopsy involves removing a small sample of tissue from the bowel wall for examination.
- A colonoscopy is a procedure where a thin, flexible tube with a camera is inserted into the anus to examine the large bowel.
Other Tests
- The Faecal Immunochemical Test (FIT) looks for blood in the stool.
- CT colonography is a scan that provides detailed images of the colon.
- A flexible sigmoidoscopy examines the lower part of the bowel.
When to See a Doctor About Colon Cancer Symptoms
Don’t wait to call your GP if:
- You’ve noticed blood in your stool more than once.
- Bowel habits have changed and stayed that way for over 3 weeks.
- You’re losing weight without trying.
- You’re unusually tired or have low iron levels.
- There’s a persistent lump or swelling in your abdomen or rectum.
It’s better to check early than to delay. Most cases of bowel cancer can be treated more effectively if caught in the early stages. Even if your symptoms turn out to be something less serious, a doctor can give you reassurance and a clear plan forward.
Final Thoughts
Colon cancer often starts with subtle symptoms that can be mistaken for minor digestive issues. Awareness of the early warning signs, proactive health monitoring, and regular screenings can make a life-saving difference. If persistent symptoms arise, seeking medical advice promptly is essential. Early diagnosis leads to better treatment outcomes and a higher chance of recovery. Book a consultation now if you are having these symptoms.
By spreading awareness, more lives can be saved through prevention and early intervention.
Frequently Asked Questions
1. What is the initial indication of colon cancer?
Changes in bowel patterns, rectal bleeding, or persistent abdominal discomfort are common early signs.
2. Where is colon pain located?
Left-sided cancers often cause noticeable abdominal pain, bloating, or rectal bleeding. Right-sided cancers may stay silent until they become more advanced.
3. Is it possible to have bowel cancer without exhibiting bleeding?
Yes. Iron deficiency anaemia can be the first sign, even without visible blood.
4. For how long can colon cancer remain undiagnosed?
It may take years for a benign polyp to become cancer, and even longer for symptoms to appear.
5. What tests confirm colon cancer?
Colonoscopy remains the gold standard for diagnosis.
6. What appearance does blood in the stool have?
It can be bright red, dark red, or black. The colour often points to the source of bleeding.
7. What are the initial signs of colon cancer?
Unexpected weight loss, narrow ribbon-like stools, rectal bleeding, and changes in bowel habits are common.
