Health condition · Clinically reviewed
Colorectal cancer, symptoms, screening, diagnosis and staged treatment.
The fourth most common cancer in the UK — with an ~90% survival rate if caught early. Symptoms, FIT screening, colonoscopy and staged treatment across all TNM stages.
Why trust this guide
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Clinically reviewed
Written by our editorial team and reviewed by a registered UK clinician before publication.
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Sourced, not summarised
Every claim is checked against NICE, ESMO or a peer-reviewed source you can see at the end.
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Updated for 2026
Reflects current UK guidance on FIT screening, staging and multimodal treatment.
Key facts
Colorectal cancer at a glance.
The essentials — what it is, how common it is, how it is diagnosed, and how modern treatment is planned around TNM stage.
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What it is
Adenocarcinoma arising from the lining of the colon or rectum, usually developing from a pre-existing polyp over years.
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How common
Around 44,000 new cases a year in the UK — the fourth most common cancer, with about a 90% survival rate when caught early.
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Screening
FIT testing has transformed screening — it detects hidden blood at very low levels and triages who needs a colonoscopy.
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Reference test
Colonoscopy remains the gold standard: it visualises the whole colon and allows biopsy in a single session.
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Rising in younger adults
Incidence in adults under 50 is rising steadily — new symptoms should not be dismissed on the basis of age alone.
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Modern treatment
Multimodal: surgery, chemotherapy and — for rectal cancer — radiotherapy, tailored to TNM stage and molecular profile.
Why this guide matters
Caught early, it’s one of the most curable cancers.
The gap between an early-stage and late-stage diagnosis is enormous. The three points below shape everything else on this page.
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Stage decides everything
Around 90% five-year survival at stage I; a fraction of that at stage IV. Symptoms warrant early investigation.
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FIT is the new front door
Faecal immunochemical testing has transformed both screening and symptomatic referral pathways in the UK.
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Age is no longer a filter
Incidence is rising in adults under 50 — new bowel symptoms should not be dismissed on age alone.
How the diagnosis is made
From symptom or FIT test to an MDT plan.
The steps a UK team will follow, in order — so you know what to expect and why each investigation matters.
Phase 1 · Screening & triage
Symptoms, FIT and colonoscopy
Phase 2 · Staging
CT, MRI and TNM
Phase 3 · MDT plan
Agreed treatment pathway
- 01
Screening & triage
Symptom review and FIT test
A quantitative faecal immunochemical test picks up hidden blood in the stool and now triages most urgent referrals.
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Screening & triage
Full blood count
Iron-deficiency anaemia in an adult, particularly a man or a post-menopausal woman, is a red flag for right-sided bowel cancer.
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Screening & triage
Urgent colonoscopy (2-week wait)
The reference test — the whole colon is examined and any suspicious lesion is biopsied in the same session.
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Staging
CT colonography if colonoscopy incomplete
Used when the caecum cannot be reached, or when a patient is too frail for a full colonoscopy.
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Staging
CT chest, abdomen and pelvis for staging
Looks for lymph-node involvement and liver or lung metastases before a treatment plan is agreed.
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Staging
MRI pelvis for rectal cancer
Defines tumour depth, mesorectal fascia involvement and node status — it drives the choice of neoadjuvant therapy.
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MDT plan
Colorectal MDT
Surgeons, oncologists, radiologists and specialist nurses agree the staged treatment plan with you.
Typical timeline: 2–6 weeks from urgent referral to a settled treatment plan.
Symptoms
What colorectal cancer can actually feel like.
Early tumours often cause nothing at all — which is why FIT screening matters. When symptoms do appear, these are the ones to act on.
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Rectal bleeding
Dark blood mixed through the stool, or persistent fresh blood — never assume it is haemorrhoids without a review.
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Change in bowel habit over 6 weeks
Looser stools, more frequent motions or a persistent change in calibre — especially in adults over 40.
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Unexplained weight loss
Losing weight without trying, especially with appetite change or fatigue, needs urgent review.
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Iron-deficiency anaemia
Low haemoglobin with low ferritin in an adult male or post-menopausal woman is bowel cancer until proven otherwise.
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Abdominal pain
New, persistent cramping — particularly colicky pain after meals — can point to a partially obstructing lesion.
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Abdominal or rectal mass
A palpable lump in the abdomen or on rectal examination warrants urgent imaging and endoscopy.
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Family history / Lynch syndrome
Two or more first-degree relatives, or a known Lynch syndrome mutation, changes screening age and interval.
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Red flag: bowel obstruction
Cramping abdominal pain with vomiting and no stool or wind — call 999 or attend an emergency department.
Treatment
How colorectal cancer is treated in the UK.
Surgery is the mainstay for cure; chemotherapy, radiotherapy, targeted therapy and immunotherapy are added according to stage and molecular profile.
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Endoscopic resection (early T1)
Small, early tumours confined to the mucosa can be removed at colonoscopy — no abdominal surgery needed.
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Colonic resection
Right or left hemicolectomy removes the affected segment with its blood supply and draining lymph nodes.
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Rectal cancer TME surgery
Total mesorectal excision — the meticulous surgery that transformed rectal cancer survival.
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Neoadjuvant chemoradiotherapy
For locally advanced rectal cancer, given before surgery to shrink the tumour and clear the margins.
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Adjuvant chemotherapy (stage III)
Given after surgery when lymph nodes are involved, to reduce the risk of recurrence.
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Metastatic chemotherapy
FOLFOX and FOLFIRI regimens are the mainstays for stage IV disease, often combined with a targeted agent.
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Targeted therapy
Anti-EGFR (cetuximab, panitumumab) for RAS wild-type tumours; anti-VEGF (bevacizumab) for many stage IV patients.
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Immunotherapy (MSI-H tumours)
Checkpoint inhibitors are now first-line for the ~5% of colorectal cancers with mismatch-repair deficiency.
What this guide is based on
The sources behind every claim on this page.
UK national guidance, European oncology guidance and specialist society standards, current at the time of last review.
Key references
Guidelines and standards we relied on.
A quiet reminder
This guide is for information, not medical advice.
Your GP or oncology team knows your history and can tell you which parts apply to you. If you have symptoms, get seen — don’t wait.
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National Institute for Health and Care Excellence (NICE). Colorectal cancer (NG151).
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European Society for Medical Oncology (ESMO). Localised and metastatic colorectal cancer clinical practice guidelines.
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Bowel Cancer UK. Patient information and support resources.
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Association of Coloproctology of Great Britain and Ireland (ACPGBI). Position statements and standards.
Red flags
When colorectal cancer becomes an emergency.
Most of the pathway is planned. These are the moments when the plan needs to change today.
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Bowel obstruction
Cramping abdominal pain, vomiting, distension and no stool or wind — call 999 or attend an emergency department.
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Massive PR bleeding
Heavy fresh rectal bleeding with dizziness or collapse needs same-day emergency assessment.
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New anaemia with fatigue
Unexplained iron-deficiency anaemia in an adult warrants an urgent 2-week-wait referral for colonoscopy.
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Weight loss with new bowel symptoms
Unintentional weight loss alongside a change in bowel habit should never be ignored, at any age.
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Family with Lynch syndrome
If a relative has a confirmed mismatch-repair mutation, cascade testing and earlier surveillance are indicated.
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Persistent pain from known metastases
New bone or liver pain in someone with a colorectal cancer history — arrange urgent oncology review.
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Post-operative anastomotic leak
Fever, tachycardia and abdominal pain in the first two weeks after bowel surgery — return to hospital immediately.
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Neutropenic sepsis on chemotherapy
Temperature 38 °C or above during chemotherapy is a medical emergency — call the oncology hotline or 999.
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Cauda equina from spinal metastases
New leg weakness, saddle numbness or bladder/bowel changes need same-day MRI — do not wait.
Living with it
A serious diagnosis, but a structured pathway.
Four things that make the biggest difference through and beyond treatment — recovery, tolerance, surveillance and family.
A quiet reminder
Flag symptoms early — always.
Small changes reported early can be managed. Ignored, they can derail an otherwise successful treatment plan.
- 01 After surgery
Bowel function will settle
It is normal for stool frequency and urgency to change for weeks to months after resection — a colorectal nurse specialist can help.
- 02 On chemotherapy
Small changes, large impact
Neuropathy, fatigue and mouth ulcers are common on FOLFOX — flag them early so doses can be adjusted before permanent harm.
- 03 Surveillance
A structured follow-up plan
CEA blood tests, CT scans and surveillance colonoscopy at agreed intervals catch recurrence at a treatable stage.
- 04 Family
Screening matters for relatives
First-degree relatives may need earlier screening — ask about genetic testing if the tumour was mismatch-repair deficient.
Frequently asked
Everything we get asked about colorectal cancer.
Quick answers on FIT, staging, survival, chemotherapy, Lynch syndrome and rising rates in younger adults.
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What is the FIT test and how accurate is it?
The faecal immunochemical test measures tiny amounts of blood in the stool. At a threshold of 10 µg Hb/g faeces it picks up the majority of colorectal cancers and now guides which symptomatic patients need an urgent colonoscopy.
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How is colorectal cancer staged?
The TNM system is used: T for tumour depth, N for lymph-node involvement and M for distant metastases. Staging combines colonoscopy findings, CT of the chest, abdomen and pelvis, and — for rectal cancer — MRI of the pelvis.
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What is the survival rate for bowel cancer in the UK?
Around 90% of people diagnosed at stage I are alive at five years. Survival falls sharply with later stages, which is why FIT screening and prompt investigation of symptoms matter so much.
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Do I need chemotherapy after surgery?
Adjuvant chemotherapy is usually recommended for stage III disease (lymph-node involvement) and for high-risk stage II. Your oncology team weighs the benefit against side effects and your general health.
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What is Lynch syndrome and should I be tested?
Lynch syndrome is an inherited condition that raises the lifetime risk of colorectal, endometrial and other cancers. All colorectal tumours in the UK are now tested for mismatch-repair deficiency, and confirmed cases lead to cascade testing of relatives.
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Why is colorectal cancer rising in people under 50?
Rates have been climbing in adults under 50 for the last two decades. The cause is not fully understood — diet, obesity and gut microbiome changes are all implicated. The practical point: new symptoms should not be dismissed because of age.
Related content
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The reference test for colorectal cancer, step by step.
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FIT bowel screen
The stool test now central to UK bowel screening.
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CT colonography
The imaging alternative when colonoscopy is incomplete.
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