Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Colon, Rectal and Bowel Cancer (Colorectal Cancer) article more useful, or one of our other health articles.
About two thirds of all colorectal tumours develop in the colon and the remainder in the rectum. Most tumours are adenocarcinomas which evolve from polyps, which may be present for ten years or more before malignancy develops. Colorectal cancer is locally invasive but metastatic spread may be evident before local growth produces symptoms. The most common site for metastatic spread is the liver. Other sites (eg, the lungs, brain and bone) are unusual in the absence of liver metastases.
- Colorectal cancer is the fourth most common cancer in the UK after breast, prostate and lung cancer.
- There were 42,300 new cases of bowel cancer registered each year in the UK in 2015-2017.
- Colorectal cancer is the second most common cause of cancer death in the UK.
- 44% of bowel cancer cases in the UK are in females, and 56% are in males.
- Age-specific incidence rates rise steeply from around age 50-54. The highest rates are in the 85 to 89 age group. About 44% of cases of colorectal cancer occur in people aged 75 or over.
- Family history of colorectal neoplasia: carcinoma; adenoma under the age of 60 years.
- Past history of colorectal neoplasm: carcinoma, adenoma.
- Inflammatory bowel disease: ulcerative colitis, Crohn's colitis.
- Polyposis syndromes: familial adenomatous polyposis (Gardner's syndrome), Turcot's syndrome, attenuated adenomatous polyposis coli, flat adenoma syndrome, hamartomatous polyposis syndromes (Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden's syndrome).
- Hereditary non-polyposis colorectal cancer (HNPCC).
- Hormonal factors: nulliparity, late age at first pregnancy, early menopause.
- Diet: rich in meat and fat; poor in fibre, folate and calcium.
- Sedentary lifestyle, obesity, smoking, high alcohol intake.
- Diabetes mellitus.
- Previous irradiation, occupational hazards - eg, asbestos exposure.
- History of small bowel cancer, endometrial cancer, breast cancer or ovarian cancer.
- The presentation depends on the site of the cancer:
- Right colon cancers: weight loss, anaemia, occult bleeding, mass in right iliac fossa, disease more likely to be advanced at presentation.
- Left colon cancers: often colicky pain, rectal bleeding, bowel obstruction, tenesmus, mass in left iliac fossa, early change in bowel habit, less advanced disease at presentation.
- The most common presenting symptoms and signs of cancer or large polyps are rectal bleeding, persisting change in bowel habit and anaemia.
- All patients with symptoms suspicious of colorectal cancer must have a thorough abdominal examination and rectal examination.
- In some patients, symptoms do not become apparent until the cancer is far advanced.
- Jaundice and hepatomegaly indicate advanced disease with extensive liver metastases. Peritoneal metastases with ascites are often also present. 20-25% of patients have clinically detectable liver metastases at the time of the initial diagnosis and a further 40-50% of patients develop liver metastases within three years of primary surgery.
- Rarer clinical signs include: pneumaturia, gastrocolic fistula, ischiorectal or perineal abscesses, deep vein thrombosis.
- Diverticular disease.
- Irritable bowel syndrome.
- Inflammatory bowel disease - eg, Crohn's disease, ulcerative colitis.
- Local rectal pathology - eg, haemorrhoids.
- Anal cancer.
- Ischaemic colitis.
- Pneumatosis coli.
Colonoscopy should be offered to patients without major comorbidity to confirm the diagnosis of colorectal cancer. If a lesion suspicious of cancer is detected, a biopsy sample should be sent for histology. Flexible sigmoidoscopy, then barium enema, can be used as an alternative to colonoscopy but an audit suggests these are much less effective and should be reserved as second-line for patients with major comorbidity.
Computerised tomographic (CT) colonography can also be used as an alternative if the local radiology service can demonstrate competency in this technique. If a lesion suspicious of cancer is detected on CT colonography, a colonoscopy with biopsy to confirm the diagnosis should be performed.
- FBC and LFTs.
- Proctoscopy with or without sigmoidoscopy if available but don't delay referral.
- Flexible sigmoidoscope can reach deep enough into the bowel to detect about 60% of tumours.
- Colonoscopy is the gold standard for diagnosis of colorectal cancer.
- Barium enema may be used if colonoscopy fails to visualise the caecum and/or the patient is unable to tolerate the procedure.
- CT colonography is an effective, safe method for examining the colon and rectum to detect abnormalities such as polyps and cancer.
- Liver ultrasound (occasionally intra-rectal ultrasound) and CT or magnetic resonance imaging (MRI) are useful in staging. MRI is more specific than CT in showing liver metastases.
- Positron emission tomography (PET) is valuable for detection of recurrent colorectal cancer, but has little effect on staging of primary cancer.
- No consensus has been reached about the most sensitive method for detection of liver metastases of colorectal cancer. A meta-analysis showed that PET is the most sensitive modality and is also especially valuable for detection of extrahepatic disease. However, no randomised study has yet proved the value of PET in this setting and therefore CT and MRI remain the diagnostic standards.
- Elevated pre-treatment serum levels of carcinoembryonic antigen (CEA) have a negative prognostic significance (CEA is of no use in screening but can be helpful in predicting relapse in patients after surgery suitable for further resection).
Refer patients, using a suspected cancer pathway referral (to be seen within two weeks):
- Aged 40 years and over with unexplained weight loss and abdominal pain; or
- Aged 50 and over with unexplained rectal bleeding; or
- Aged 60 and over with:
- Iron-deficiency anaemia; or
- Changes in bowel habit; or
- Tests show occult blood in their faeces.
- Consider a suspected cancer pathway referral in adults with an abdominal or rectal mass.
- Consider a suspected cancer pathway in adults aged under 50 with rectal bleeding and any of the following unexplained symptoms or findings:
- Abdominal pain.
- Weight loss.
- Change in bowel habit.
- Iron-deficiency anaemia.
Contrast-enhanced CT of the chest, abdomen and pelvis should be used to estimate the stage of disease for patients with colon cancer. MRI should be used to assess the risk of local recurrence (as determined by anticipated resection margin, tumour and lymph node staging) in all patients with rectal cancer. Endorectal ultrasound should be offered if MRI shows disease amenable to local excision or if MRI is contra-indicated.
The Dukes' staging classification is as follows:
- Dukes' A - the cancer is only in the innermost lining of the bowel or slightly growing into the muscle layer.
- Dukes' B - the cancer has grown through the muscle layer of the bowel.
- Dukes' C - the cancer has spread to at least one lymph node close to the bowel.
- Dukes' D - the cancer has metastasised to other areas - eg, the liver, lungs or bones.
The Dukes system is now gradually being replaced by the tumour/node/metastases (TNM) classification:
- TX: primary cannot be assessed:
- T0: no evidence of primary carcinoma in situ (Tis) - intraepithelial or lamina propria only.
- T1: invades submucosa.
- T2: invades muscularis propria.
- T3: invades subserosa or non-peritonealised pericolic tissues.
- T4: directly invades other tissues and/or penetrates visceral peritoneum.
- NX: regional nodes cannot be assessed:
- N0: no regional nodes involved.
- N1: 1-3 regional nodes involved.
- N2: 4 or more regional nodes involved.
- MX: distant metastasis cannot be assessed:
- M0: no distant metastasis.
- M1: distant metastasis present (may be transcoelomic spread).
Colorectal cancer can then be staged as follows:
- Stage 0: carcinoma in situ (CIS).
- Stage 1: cancer growth through the inner lining of the bowel, or into the muscle wall, but no further. There is no cancer in the lymph nodes (T1, N0, M0 or T2, N0, M0).
- Stage 2: further local spread of the cancer but no lymph nodes are affected (N0) and the cancer has not spread to another area of the body (M0):
- Stage 2a: cancer growth into the outer covering of the bowel wall (T3, N0, M0).
- Stage 2b: cancer growth through the outer covering of the bowel wall and into tissues or organs next to the bowel (T4).
- Stage 3: lymph node involvement:
- Stage 3a: cancer growth into the muscle layer, and between 1 and 3 nearby lymph nodes contain cancer cells (T1, N1, M0 or T2, N1, M0).
- Stage 3b: cancer growth into the outer lining of the bowel wall or into surrounding body tissues or organs, and between 1 and 3 nearby lymph nodes contain cancer cells (T3, N1, M0 or T4, N1, M0).
- Stage 3c: cancer growth of any local size but has spread to 4 or more nearby lymph nodes (any T, N2, M0).
- Stage 4: cancer has spread to other parts of the body - eg, liver or lungs - (any T, any N, M1).
Colorectal cancer can also be graded according to the cancer cell differentiation:
- Grade 1 (low grade): well differentiated.
- Grade 2 (moderate grade): moderately differentiated.
- Grade 3 (high grade): poorly differentiated.
Surgery remains the definitive treatment for apparently localised colorectal cancer. Both radiotherapy and chemotherapy can improve survival rates after potentially curative surgery.
If colonic stents are considered for patients presenting with acute large bowel obstruction, CT of the chest, abdomen and pelvis should be offered to confirm the diagnosis of mechanical obstruction, and to determine whether the patient has metastatic disease or colonic perforation.
May be performed either to attempt cure (removing the draining lymphatic field) or to relieve symptoms:
- Right hemicolectomy: for tumours in the caecum, ascending and proximal transverse colon.
- Left hemicolectomy: if in the distal transverse colon or descending colon.
- Sigmoid colectomy: for tumours of the sigmoid colon.
- Anterior resection: if in the low sigmoid or high rectum. Anastomosis is achieved at the first operation.
- Abdomino-perineal (AP) resection: for tumours low in the rectum (less than approximately 8 cm from the anal canal). Permanent colostomy and removal of rectum and anus.
- Laparoscopic surgery has become the gold standard for surgical treatment. However, a recent meta-analysis has shown no difference in oncological outcomes of laparoscopy for treating rectal cancer.
- One of the most important advances for surgery of rectal cancer has been the concept of total mesorectal excision, which reduces local recurrences and peri-operative morbidity. The transanal route seems to be comparable to the laparoscopic route although further research is needed.
- Pre-operative high-dose rate brachytherapy can be used in patients with cancer in the middle or lower third of the rectum to shrink the tumour. There is evidence for short-term safety and efficacy in reducing tumour bulk. However, there is no evidence for any additional benefit when used as a boost to external beam radiotherapy. Evidence on the clinical efficacy if used without external beam radiotherapy is inadequate in quantity.
- All patients with resectable liver metastases should be considered for surgical resection.
- Radiotherapy is an established treatment for locally advanced rectal cancer. However, it has significant adverse effects and there is a range of opinion on its risks and benefits in individual patients.
- The National Institute for Health and Care Excellence (NICE) recommends that radiofrequency ablation should be considered for colorectal liver metastases in patients unfit or otherwise unsuitable for hepatic resection, or in those who have previously had hepatic resection.
- Selective internal radiation therapy (SIRT) for unresectable colorectal metastases in the liver can cause serious complications, but these are well recognised and infrequent. NICE recommends that this procedure should only be used with special arrangements for clinical governance, consent, and audit or research for people who cannot tolerate chemotherapy or have liver metastases that are refractory to chemotherapy, and should only be used in the context of research for people who can have chemotherapy.
- NICE recommends that when offering multiple chemotherapy drugs to patients with advanced and metastatic colorectal cancer, one of the following sequences of chemotherapy should be considered unless contra-indicated:
- FOLFOX (= folinic acid plus fluorouracil plus oxaliplatin) as first-line treatment, then single agent irinotecan as second-line treatment; or
- FOLFOX as first-line treatment, then FOLFIRI (= folinic acid plus fluorouracil plus irinotecan) as second-line treatment; or
- XELOX (= capecitabine plus oxaliplatin) as first-line treatment, then FOLFIRI as second-line treatment.
- Raltitrexed should only be considered for patients with advanced colorectal cancer who are intolerant to 5-fluorouracil and folinic acid, or if these drugs are not suitable.
- NICE has recommended that capecitabine or tegafur with uracil (and folinic acid), to be taken by mouth, should be among the first options considered for a person with metastatic colorectal cancer.
- Capecitabine and oxaliplatin are recommended as possible adjuvant treatments after surgery for stage III (Dukes' C) colon cancer:
- Capecitabine is given on its own.
- Oxaliplatin is given together with 5-fluorouracil and folinic acid.
- Cetuximab in combination with FOLFOX or FOLFIRI is recommended for the first-line treatment of metastatic colorectal cancer only when all of the following criteria are met:
- The primary colorectal tumour has been resected or is potentially operable.
- The metastatic disease is confined to the liver and is unresectable.
- The patient is fit enough to undergo surgery to resect the primary colorectal tumour and to undergo liver surgery if the metastases become resectable after treatment with cetuximab.
- Bevacizumab in combination with oxaliplatin and either fluorouracil plus folinic acid or capecitabine is not recommended for the treatment of metastatic colorectal cancer.
- Over 50% of patients with colorectal cancer will develop liver metastases but only a minority of patients present with technically resectable disease.
- Liver resection, with neoadjuvant and adjuvant chemotherapy, is the optimal treatment for colorectal metastases. Around 40% of those undergoing surgical resection are alive five years after their diagnosis.
- Recurrence rate is significant and may require further resection.
- The lungs are the second most common site of metastasis for colorectal cancer after the liver. Management is multidisciplinary and therapeutic options include systemic therapy, radical local treatment (eg, surgical resection, stereotactic radiation therapy, and ablation therapy), and local palliative treatment.
Follow-up after apparently curative resection
- A minimum of two CT scans of the chest, abdomen, and pelvis in the first three years; and
- Regular serum CEA tests (at least every six months in the first three years).
Current research centres on the identification of specific biomarkers which could be used to tailor chemotherapy to the individual patient.
Around half of people diagnosed with colorectal cancer survive for at least five years after diagnosis:
- 60% are amenable to radical surgery and 70% of these will be alive at seven years (or will have died from non-tumour-related causes).
- Survival rates relative to age-matched groups without colorectal cancer, are now about 45% at five years after diagnosis. Beyond five years, relative survival rates decline only slightly (most of those who live this long are cured).
- Survival rates in the UK have been rising steadily over a period of three decades.
Lower risk has been linked with:
- Lifestyle: infrequent consumption of meat, matching calorie consumption to need, low dietary fat, active lifestyle, not smoking, frequent consumption of vegetables and possibly fruit, high-fibre diet.
- Nutritional supplements and medication: vitamin supplements containing folic acid, selenium, calcium, regular use of non-steroidal anti-inflammatory drugs (NSAIDs), hormone replacement therapy[23, 24, 25].
- A UK general practice study found that patients starting low-dose aspirin therapy (75-300 mg daily) have a reduced risk of stages B-D colorectal cancer, suggesting a role for low-dose aspirin in the progression of established disease; a substantial reduction in the risk of Dukes' A colorectal cancer may occur after five years of therapy.
Further reading and references
Recio-Boiles A et al; Cancer, Colon, 2019.
Chang H, Lei L, Zhou Y, et al; Dietary Flavonoids and the Risk of Colorectal Cancer: An Updated Meta-Analysis of Epidemiological Studies. Nutrients. 2018 Jul 2310(7). pii: nu10070950. doi: 10.3390/nu10070950.
Li D; Recent advances in colorectal cancer screening. Chronic Dis Transl Med. 2018 Sep 174(3):139-147. doi: 10.1016/j.cdtm.2018.08.004. eCollection 2018 Sep.
White A, Ironmonger L, Steele RJC, et al; A review of sex-related differences in colorectal cancer incidence, screening uptake, routes to diagnosis, cancer stage and survival in the UK. BMC Cancer. 2018 Sep 2018(1):906. doi: 10.1186/s12885-018-4786-7.
Bowel Cancer Statistics; Cancer Research UK, 2018
Bowel Cancer Risk; Cancer Research UK, 2019
Beebe-Dimmer JL, Yee C, Paskett E, et al; Family history of prostate and colorectal cancer and risk of colorectal cancer in the Women's health initiative. BMC Cancer. 2017 Dec 1317(1):848. doi: 10.1186/s12885-017-3873-5.
Colorectal cancer (management in people aged 18 and over); NICE Guidance (January 2020)
Kuipers EJ, Grady WM, Lieberman D, et al; Colorectal cancer. Nat Rev Dis Primers. 2015 Nov 51:15065. doi: 10.1038/nrdp.2015.65.
Than M, Witherspoon J, Shami J, et al; Diagnostic miss rate for colorectal cancer: an audit. Ann Gastroenterol. 2015 Jan-Mar28(1):94-98.
Computed tomographic colonography (virtual colonoscopy); NICE Interventional Procedures Guidance, June 2005
Suspected cancer: recognition and referral; NICE Clinical Guideline (2015 - last updated July 2017)
Bowel cancer (colorectal cancer); Cancer Research UK
Diagnosis and management of colorectal cancer; Scottish Intercollegiate Guidelines Network - SIGN (December 2011, revised August 2016).
Malczak P, Mizera M, Torbicz G, et al; Is the laparoscopic approach for rectal cancer superior to open surgery? A systematic review and meta-analysis on short-term surgical outcomes. Wideochir Inne Tech Maloinwazyjne. 2018 Jun13(2):129-140. doi: 10.5114/wiitm.2018.75845. Epub 2018 May 16.
Rubinkiewicz M, Nowakowski M, Wierdak M, et al; Transanal total mesorectal excision for low rectal cancer: a case-matched study comparing TaTME versus standard laparoscopic TME. Cancer Manag Res. 2018 Nov 110:5239-5245. doi: 10.2147/CMAR.S181214. eCollection 2018.
Preoperative high dose rate brachytherapy for rectal cancer; Interventional Procedure Guidance, August 2015
Kim JH; Controversial issues in radiotherapy for rectal cancer: a systematic review. Radiat Oncol J. 2017 Dec35(4):295-305. doi: 10.3857/roj.2017.00395. Epub 2017 Dec 29.
Radiofrequency ablation for the treatment of colorectal liver metastases; NICE Interventional Procedure Guideline, December 2009
Selective internal radiation therapy for unresectable colorectal metastases in the liver; NICE Interventional Procedure Guidance, March 2020.
Guidance on the use of capecitabine and tegafur with uracil for metastatic colorectal cancer; NICE Technology Appraisal, May 2003
Capecitabine and oxaliplatin in the adjuvant treatment of stage III (Dukes' C) colon cancer; NICE Technology Appraisal, April 2006
Bevacizumab in combination with oxaliplatin and either fluorouracil plus folinic acid or capecitabine for the treatment of metastatic colorectal cancer; NICE Technology Appraisal, December 2010
Jones RP, Kokudo N, Folprecht G, et al; Colorectal Liver Metastases: A Critical Review of State of the Art. Liver Cancer. 2016 Nov6(1):66-71. doi: 10.1159/000449348. Epub 2016 Nov 29.
Li J, Yuan Y, Yang F, et al; Expert consensus on multidisciplinary therapy of colorectal cancer with lung metastases (2019 edition). J Hematol Oncol. 2019 Feb 1412(1):16. doi: 10.1186/s13045-019-0702-0.
Lech G, Slotwinski R, Slodkowski M, et al; Colorectal cancer tumour markers and biomarkers: Recent therapeutic advances. World J Gastroenterol. 2016 Feb 722(5):1745-55. doi: 10.3748/wjg.v22.i5.1745.
Kolligs FT; Diagnostics and Epidemiology of Colorectal Cancer. Visc Med. 2016 Jun32(3):158-64. doi: 10.1159/000446488. Epub 2016 Jun 16.
Du W, Fang JY; Nutrients Impact the Pathogenesis and Development of Colorectal Cancer. Gastrointest Tumors. 2016 May2(4):203-7. doi: 10.1159/000441212. Epub 2015 Oct 10.
Tsioulias GJ, Go MF, Rigas B; NSAIDs and Colorectal Cancer Control: Promise and Challenges. Curr Pharmacol Rep. 2015 Oct 11(5):295-301. doi: 10.1007/s40495-015-0042-x. Epub 2015 May 14.
Garcia Rodriguez LA, Soriano-Gabarro M, Bromley S, et al; New use of low-dose aspirin and risk of colorectal cancer by stage at diagnosis: a nested case-control study in UK general practice. BMC Cancer. 2017 Sep 717(1):637. doi: 10.1186/s12885-017-3594-9.