Change in bowel habits
Persistent diarrhoea, constipation or a change in your usual bowel pattern.
Patient Guide · Colon and Rectal Cancer
Understanding Colon and Rectal Cancer
Practical information to help you recognise symptoms, understand diagnosis and discuss treatment decisions with your doctor.
This guide supports informed conversations with your doctor. It does not replace an individual medical assessment.
How to use this guide
Use these sections to understand possible next steps, prepare questions and discuss your options with your doctor.
Warning signs
Recognise persistent bowel changes and other symptoms.
Diagnosis
Learn about colonoscopy, biopsy and staging.
Treatment
Understand surgery and other treatment options.
Consultation
Know what to bring and which questions to ask.
What to look for
Warning signs of colon and rectal cancer
Symptoms may have several causes. Persistent, recurrent or unexplained changes should be assessed.
Blood in stool
Red blood in the stool or black, tarry stool should be assessed. Bleeding has several possible causes.
Abdominal pain or cramps
Ongoing cramps, bloating or a feeling of fullness in the abdomen.
Unexplained weight loss
Losing weight without trying, particularly with changes in bowel habits or appetite.
Persistent tiredness
Ongoing fatigue may occur, sometimes due to anaemia from slow blood loss.
Persistent change in stool shape
A sustained change in stool form or difficulty emptying the bowel needs assessment, though it is not specific to cancer.
When should you seek medical advice?
Arrange assessment for rectal bleeding, persistent bowel-habit changes, unexplained anaemia or weight loss. Heavy bleeding, fainting, severe abdominal pain, repeated vomiting or inability to pass stool or gas with abdominal swelling may require urgent medical care.
Understanding risk
Factors associated with colorectal cancer
Risk factors influence probability but cannot determine whether an individual has cancer.
Increasing age
Risk generally increases with age, although colorectal cancer can also occur in younger adults.
Polyps
Some colorectal polyps can develop into cancer over time. Finding and removing precancerous polyps can reduce risk.
Family history
A close relative with colorectal cancer or advanced polyps may increase your risk.
Inflammatory bowel disease
Long-standing ulcerative colitis or Crohn's colitis can increase risk in some patients.
Diet and lifestyle
Risk is associated with factors such as processed meat intake, low physical activity, excess body weight and smoking.
Inherited conditions
Conditions such as Lynch syndrome and familial adenomatous polyposis can substantially increase risk.
If you have a strong family history, a known inherited syndrome or inflammatory bowel disease, ask your clinician whether you need an individual surveillance plan.
Getting a clear diagnosis
How colon and rectal cancer is diagnosed
Colonoscopy and biopsy are central to diagnosis. Imaging helps determine the extent of disease and plan treatment.
1
Clinical evaluation
Your doctor reviews symptoms, family history, medicines, abdominal findings and general health.
2
Colonoscopy
A flexible camera examines the colon and rectum. Polyps can often be removed and suspicious areas sampled.
3
Biopsy and pathology
Tissue is examined to confirm cancer and identify important tumour features.
4
Staging investigations
CT scans and, for rectal cancer, pelvic MRI are commonly used to assess extent and guide treatment planning.
Why the exact location matters
Colon and rectal cancers can need different treatment sequences. Pelvic MRI is often important in rectal cancer planning, while colon cancer staging commonly relies on CT and pathology. Your team uses these findings to discuss the most appropriate plan.
Treatment decisions
Colon and rectal cancer treatment options
Treatment depends on tumour location, stage, pathology, molecular features and your overall health.
Surgery
The operation depends on tumour location. It may involve removing a segment of colon or performing a rectal cancer operation, with lymph-node assessment.
Chemotherapy
May be recommended before or after surgery, or for cancer that has spread, depending on stage and tumour features.
Radiotherapy
Used particularly in selected rectal cancers, often with chemotherapy before surgery or as part of a tailored plan.
Targeted therapy
For selected advanced cancers, treatment may be guided by tumour markers and molecular testing.
Immunotherapy
May be suitable for certain colorectal cancers, particularly some with mismatch-repair deficiency or high microsatellite instability.
Will I need a stoma?
Not everyone needs a stoma. If recommended, it may be temporary or permanent depending on the operation, tumour location, healing and individual factors. Discuss this possibility with your surgeon before surgery.
Why molecular testing may matter
For selected cancers, testing for markers such as mismatch-repair status and other molecular changes can help guide treatment choices, particularly when disease is advanced.
What happens next
Your treatment journey
This is a general overview. The sequence depends on whether the cancer is in the colon or rectum and on its stage.
STEP 1
Consultation
Discuss symptoms, duration, bowel changes, family history and previous reports.
STEP 2
Confirm diagnosis
Colonoscopy and biopsy help establish the diagnosis.
STEP 3
Determine site and stage
Scans and pathology guide the plan. Rectal cancer may need pelvic MRI.
STEP 4
Discuss treatment
The team considers surgery, systemic treatment, radiotherapy where appropriate and treatment sequence.
STEP 5
Treatment and recovery
Care may include bowel function support, nutrition, stoma education if relevant and recovery planning.
STEP 6
Follow-up
Follow-up may include clinical review, blood tests, scans and colonoscopy according to the care plan.
Preparing for your consultation
Bring your reports and note any changes in symptoms over time.
- Colonoscopy and biopsy/pathology reports
- Scan reports and images, including pelvic MRI if performed
- Blood test results and current medicines
- Previous operation notes or treatment details
- Your questions and a support person, if you prefer
Surgical oncology consultation
Discuss your colon and rectal cancer treatment options
Dr. Abhishek Kumar Verma (MCh), Surgical Oncologist, can review your reports, explain surgical options and discuss how surgery fits into your overall treatment pathway.
Recommendations are made after reviewing your individual diagnosis and clinical findings.
Common questions
Colon and rectal cancer FAQs
Select a question to read the answer.
Q1.Does blood in the stool always mean colorectal cancer?
No. Haemorrhoids, fissures and other conditions can cause bleeding. However, unexplained or recurrent bleeding should not be assumed to be piles; it needs appropriate assessment.
Q2.Are colon cancer and rectal cancer treated the same way?
Not always. Surgery is central for many localised cancers, but rectal cancer often requires pelvic MRI and may need radiotherapy and/or chemotherapy before surgery. The plan depends on location, stage and tumour features.
Q3.Will I need a stoma?
Not every patient needs a stoma. It may be temporary or permanent depending on tumour location, the operation required, healing and individual clinical factors. Your surgeon should discuss the possibility before treatment.
Q4.What should I bring for a second opinion?
Bring colonoscopy and biopsy reports, scan images and reports, blood test results, previous operation notes if applicable, current medicines and any molecular test results.
Q5.Can colorectal cancer occur in younger adults?
Yes. Although risk rises with age, younger adults can develop colorectal cancer. Persistent symptoms or rectal bleeding should be assessed rather than dismissed because of age.
Take the next step
Get clarity on your diagnosis and options
Arrange a consultation or seek a second opinion to discuss your treatment plan.
This page is for education and does not substitute for examination, diagnosis or personalised medical advice. Rectal bleeding, persistent bowel changes or unexplained weight loss should be assessed by a qualified clinician.