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10 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
The cancer where screening works best and where immunotherapy can make some tumours disappear entirely; chemotherapy still carries most metastatic disease, now with antibodies and targeted combinations chosen by RAS, BRAF, mismatch repair and which side of the bowel the tumour started on.
Colorectal cancer is the disease where screening works best: removing adenomas at colonoscopy prevents cancer, stool and blood tests catch it early, and localised disease is cured by surgery. It is the third most common cancer worldwide (about 1.9 million cases a year) and, because many are still found late, the second most common cause of cancer death (900,000 a year). Most cases arise through the adenoma-carcinoma sequence driven by APC loss, KRAS mutation, and TP53 loss (chromosomal instability); about 15% arise through mismatch-repair deficiency (dMMR/MSI-high), either sporadically via MLH1 methylation or through Lynch syndrome. Incidence is rising sharply in adults under 50 for reasons that remain unexplained.
How common it is, world and United States. The IARC fact sheets, served with the GLOBOCAN 2024 estimates, count the colon and the rectum separately: 1,206,011 new colon cancers a year (the 4th commonest cancer, age-standardised rate 10.8 per 100,000) with 556,774 deaths (the 5th commonest cause of cancer death, 4.7 per 100,000), and 778,594 rectal cancers (8th, 7.3 per 100,000) with 339,370 deaths (9th, 3.0 per 100,000). Added together that is 1,984,605 new cases and 896,144 deaths a year, which is where the familiar round figures of about 1.9 million cases and about 900,000 deaths come from. Asia has 49.3 percent of colon cases, Europe 27.2 percent, Northern America 10.6 percent, Latin America and the Caribbean 8.3 percent, Africa 3.4 percent and Oceania 1.3 percent. In the United States the SEER programme projects 158,850 new cases (7.5 percent of all cancers) and 55,230 deaths (8.8 percent of cancer deaths) for 2026, making colorectal cancer the 4th commonest cancer diagnosed and the 2nd commonest cause of cancer death; the rate of new cases is 37.6 per 100,000 a year (2019 to 2023) and the death rate 12.7 (2020 to 2024); the median age at diagnosis is 66 and at death 72; about 3.9 percent of Americans will be diagnosed in their lifetime; and 1,478,528 people were living with the disease in 2023. Rates differ by group: 59.5 per 100,000 in non-Hispanic American Indian and Alaska Native men and 50.1 in non-Hispanic Black men against 42.9 in non-Hispanic White men (SEER).
| Setting | Approach | Guideline |
|---|---|---|
| The operation and what a stoma means: temporary or permanent | Removing the cancer with a rim of healthy bowel, and joining the two ends back together, is what cures most bowel cancer. The operation depends on where the tumour sits. Macmillan names the colon operations as a right or left hemi-colectomy, a sigmoid colectomy (also called a high anterior resection), a transverse colectomy or a total colectomy, and the rectal ones as a local excision for a very small stage 1 cancer, an anterior resection or low anterior resection for the upper or middle rectum, usually with a total mesorectal excision, and it says that if the cancer is very low in the rectum and close to the anus you are more likely to need a permanent stoma. NICE NG151 recommends laparoscopic (keyhole) resection as an alternative to open resection for both colon and rectal cancer when both are suitable, says to consider open surgery for locally advanced tumours or after previous abdominal or pelvic surgery, and to use robotic surgery only within established programmes with audited outcomes. It sets volume floors for rectal surgery: at least 10 major resections a year per hospital and at least 5 per surgeon. On the stoma, NICE asks teams to advise people of the likelihood of having one, why it might be necessary and for how long it might be needed, and to have a trained stoma professional provide information on care and on learning to live with it. Bowel Cancer UK puts it plainly: a reversible stoma is formed to let the join heal and a permanent one when the two ends cannot be joined, and the surgeon may not know for certain until the operation has started. A colostomy is formed from the large bowel and the output is more solid; an ileostomy is formed from the small bowel, the output is looser and more fluid and salt are lost. The NHS says recovery from a colostomy usually takes about 8 weeks, with no heavy lifting in that time, and that permanent colostomy supplies come free on prescription. Prehabilitation before the operation and an enhanced recovery programme after it are both worth asking about: NICE says to explain what recovery protocols involve and their value, and Bowel Cancer UK says prehabilitation reduces anxiety, improves fitness and can shorten the stay. | not mapped |
| Chemotherapy after surgery for stage 2 and stage 3, and how the benefit is worked out | Chemotherapy after the operation is given to kill cells that have already left the bowel but are too few to see, and the whole decision is about how large that risk is against what the treatment costs you. For stage 3 (cancer in the lymph nodes), NICE NG151 is explicit and the same for colon and for rectal cancer treated with short-course radiotherapy or no preoperative treatment: offer capecitabine with oxaliplatin (CAPOX) for 3 months, or if that is not suitable either oxaliplatin with fluorouracil and folinic acid (FOLFOX) for 3 to 6 months, or a single-agent fluoropyrimidine such as capecitabine for 6 months. It then says to base the choice on the person's histopathology (giving pT1 to T3 with pN1 against pT4 or pN2 as the example), performance status, personal preferences, comorbidities and age, which is the guideline's way of saying that three months of a doublet and six months of a single tablet are both defensible and the balance is yours to weigh. For stage 2 (no nodes involved) NICE NG151 makes no adjuvant recommendation at all, so the conversation runs on individual risk features, on the mismatch repair result, and increasingly on whether circulating tumour DNA is detectable after surgery; the ctDNA-guided studies on this record (DYNAMIC and the others) are where that question is being settled, and a trial is a reasonable answer. Two practical points NICE puts in writing: monitor prolonged sensory symptoms after platinum chemotherapy, because they are a sign the dose needs reducing to prevent permanent neuropathy, and a DPD blood test comes before fluorouracil or capecitabine because low DPD raises the risk of severe toxicity. The OnCo decision aid at /tools/colorectal-adjuvant-chemotherapy/ lays the NICE wording out by site, stage and fitness for oxaliplatin. | not mapped |
| Rectal cancer: surgery or chemoradiotherapy first, and watch and wait if the tumour disappears | Rectal cancer is the part of bowel cancer where the order of treatment is a real choice. NICE NG151 says not to offer preoperative radiotherapy for early rectal cancer (cT1 to T2, cN0, M0) outside a clinical trial, and to offer preoperative radiotherapy or chemoradiotherapy where the cancer is cT1 to T2 with involved nodes, or cT3 to T4 with any node status. Two forms are used: a short course of radiotherapy on its own, and a longer course of radiotherapy given together with chemotherapy (Macmillan says the drug most commonly used is capecitabine tablets, started on the first morning of radiotherapy and taken throughout it, with a DPD test first), and in recent practice both are often followed by several months of chemotherapy before surgery (total neoadjuvant therapy, tested in RAPIDO, PRODIGE 23 and OPRA on this record; PROSPECT asked the opposite question, whether chemotherapy alone can replace radiotherapy in selected tumours). The reason this matters to a patient is that treatment before surgery shrinks the tumour, improves the chance of a clear margin, and in a minority makes the tumour disappear altogether on examination, MRI and endoscopy. NICE NG151 covers that case directly: inform people with a complete clinical and radiological response who wish to defer surgery that there is a risk of recurrence, and that there are no prognostic factors to guide selection for deferral; for those who choose to defer, encourage participation in a clinical trial and ensure data is collected via a national registry. Watch and wait is therefore not less treatment but a different commitment, to frequent examination and scans for years. For early rectal cancer NICE offers a shared decision between transanal excision, endoscopic submucosal dissection and total mesorectal excision, and gives a table comparing them on exactly the points a patient asks about: whether bowel is removed, whether a stoma is possible, hospital stay, scarring and the complications of each. | not mapped |
| Which first treatment when the cancer has spread, by RAS, BRAF, mismatch repair and which side of the bowel | When bowel cancer has spread, the first treatment is chosen by three test results and one piece of anatomy. NICE NG151 says to test for RAS and BRAF V600E mutations in all people with metastatic colorectal cancer suitable for systemic anticancer treatment, and separately recommends immunotherapy where the tumour is MSI-high or mismatch repair deficient. If RAS is wild-type, NICE recommends cetuximab or panitumumab with FOLFOX or FOLFIRI; if RAS is mutated, those antibodies do not work and bevacizumab with fluoropyrimidine-based chemotherapy is recommended where targeted treatment or immunotherapy is unsuitable. The anatomy is sidedness: cancers that start on the left (descending colon, sigmoid, rectum) respond better to the EGFR antibodies than cancers that start on the right, which is why the standard-of-care rows put anti-EGFR treatment with left-sided RAS wild-type disease and bevacizumab with right-sided or RAS-mutant disease (PARADIGM tested that question head to head; CRYSTAL and FIRE-3 are the older comparisons). BRAF V600E is its own group, with encorafenib and cetuximab added to chemotherapy (BREAKWATER). What this means at the appointment is that the first question is not which drug but which result, and that a treatment plan made before the molecular report is back may change. Two further decisions sit alongside: whether the primary tumour should be removed when it is causing no symptoms (NICE says consider it, and supplies a table of advantages and disadvantages to share), and when to take a break from oxaliplatin before the nerve damage becomes permanent. | not mapped |
| Surgery or ablation when the cancer has spread to the liver | Bowel cancer that has spread to the liver is one of the few settings in which surgery for metastatic disease is done with the intention of cure, and a meaningful number of people live many years after it. NICE NG151 says to consider resection, either simultaneous with the bowel operation or sequential, after discussion by a multidisciplinary team with expertise in resection of disease in all involved sites, and to consider perioperative systemic anticancer therapy where liver resection is a suitable treatment. Where the liver disease is not resectable, it says to consider chemotherapy with local ablative techniques after discussion by a specialist multidisciplinary team, and not to offer selective internal radiation therapy as first-line treatment for liver metastases unsuitable for local treatment except under the arrangements its HealthTech guidance sets out. The same logic extends to the lungs: consider metastasectomy, ablation or stereotactic body radiation therapy for lung metastases suitable for local treatment, after discussion by a team including a thoracic surgeon and a specialist in non-surgical ablation, and consider a biopsy for a single lung lesion to exclude a primary lung cancer. For disease limited to the peritoneum, NICE says to offer systemic therapy and, within the multidisciplinary team, to discuss referral to a nationally commissioned specialist centre to consider cytoreductive surgery with heated intraperitoneal chemotherapy. The practical consequence for a patient is that the answer to whether an operation is possible depends on which team is looking, so asking whether a specialist liver or peritoneal unit has seen the scans is a fair question, and a second opinion is a recognised step (Bowel Cancer UK has a page on it). | not mapped |
| Immunotherapy when the tumour is mismatch repair deficient | A small minority of bowel cancers that have spread have lost the mismatch repair machinery that proof-reads DNA, which leaves the tumour carrying very many mutations and makes it visible to the immune system. For those people, immunotherapy has replaced chemotherapy as the first treatment. NICE NG151 recommends nivolumab with ipilimumab as an option for untreated unresectable or metastatic colorectal cancer with high microsatellite instability or mismatch repair deficiency, and pembrolizumab as an option for untreated metastatic disease with the same markers, stopped after 2 years or earlier if the disease progresses; after fluoropyrimidine-based combination chemotherapy it recommends nivolumab with ipilimumab, and pembrolizumab only if that combination cannot be used. KEYNOTE-177 and CheckMate 8HW are the trials behind those recommendations and are on this record. The same biology is being tested before surgery, where a few weeks of immunotherapy has cleared the tumour in a large fraction of mismatch repair deficient colon cancers (NICHE-2) and of rectal cancers (the dostarlimab work and the registrational AZUR-1), but outside those trials NICE does not recommend it, so the question at the clinic is whether a trial is open. Everything therefore turns on the test: ask whether mismatch repair immunohistochemistry or microsatellite instability testing has been done and what the result was, because a mismatch repair deficient result also starts the Lynch syndrome pathway for your family. | not mapped |
| Later lines, when chemotherapy stops working | When the cancer grows through the first and second lines, there is still a recognised sequence, and knowing it in advance makes each step less sudden. NICE NG151 points to its appraisals for metastatic colorectal cancer previously treated with fluoropyrimidine-based chemotherapy, anti-VEGF or anti-EGFR therapy: trifluridine with tipiracil plus bevacizumab after 2 systemic treatments (the SUNLIGHT combination), fruquintinib after 2 systemic treatments if trifluridine with tipiracil plus bevacizumab is not suitable (FRESCO-2), regorafenib, and trifluridine with tipiracil alone. It also lists what is not recommended at this point, including aflibercept with irinotecan and fluorouracil after oxaliplatin, and cetuximab or panitumumab monotherapy after first-line chemotherapy. Where a rarer change is present the sequence changes: encorafenib with cetuximab for BRAF V600E after previous systemic treatment, larotrectinib through the Cancer Drugs Fund for NTRK fusion-positive tumours when there are no other satisfactory options, and the HER2 and KRAS G12C options on this record's other rows. These drugs are given to hold the cancer and protect quality of life rather than to cure, so the honest questions are what each is likely to buy, what it costs in side effects and hospital visits, how progression will be recognised, and what the stopping rule is. Bowel Cancer UK has pages on treating advanced bowel cancer and on taking a break from treatment; both are legitimate choices, and so is a trial. | not mapped |
| Lynch syndrome testing, and what it means for your family | Around 3 in 100 UK bowel cancers are caused by Lynch syndrome, an inherited fault in one of the mismatch repair genes, and Bowel Cancer UK says testing should be offered to everyone at diagnosis because the result changes treatment as well as family risk. The route runs in order: the tumour is stained for the mismatch repair proteins (or tested for microsatellite instability); where MLH1 is lost, the laboratory checks for MLH1 promoter methylation, which usually means the loss is sporadic rather than inherited; and where the pattern still suggests an inherited cause, a germline blood test is offered through the genomics service. A positive result has three consequences. For you, immunotherapy becomes an option in advanced disease, and lifelong colonoscopy surveillance begins. For your relatives, each child, brother and sister has a one in two chance of carrying the same change, and Bowel Cancer UK says they should be offered the same test, which it calls cascade testing; it estimates that most of the 175,000 to 200,000 people in the UK with Lynch syndrome do not know. For prevention, NICE NG151 says to consider aspirin, taken daily and for a period of more than 2 years, to reduce the risk of colorectal cancer in people with Lynch syndrome, noting that in January 2020 this was an off-label use and that NICE has produced a patient decision aid to support the discussion. Bowel Cancer UK says surveillance means colonoscopy every 18 months to two years and can reduce the chance of dying from bowel cancer by as much as 72 percent. | not mapped |