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Colorectal cancer: Difference between revisions
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(Created page with "Colorectal carcinoma (<abbr>CRC</abbr>) refers to all cancers that can affect the colon and rectum. Carcinomas in the colon are the most common malignancy in the <abbr>GI</abbr>-tract, accounting for 95% of all GI cancers. CRC is the third most common type of cancer, but it’s the second most common cause of cancer-related death. It accounts for 10% of the world’s cancers. It’s mostly a disease of elderly, affecting those in their 60s and 70s. >90% of colorectal ca...") |
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Colorectal carcinoma (<abbr>CRC</abbr>) refers to all cancers that can affect the colon and rectum. Carcinomas in the colon are the most common malignancy in the <abbr>GI</abbr>-tract, accounting for 95% of all GI cancers. | '''Colorectal carcinoma''' (<abbr>CRC</abbr>) refers to all cancers that can affect the colon and rectum. Carcinomas in the colon are the most common malignancy in the <abbr>GI</abbr>-tract, accounting for 95% of all GI cancers. | ||
CRC is the third most common type of cancer, but it’s the second most common cause of cancer-related death. It accounts for 10% of the world’s cancers. It’s mostly a disease of elderly, affecting those in their 60s and 70s. >90% of colorectal cancers develop from adenomatous polyps of the colon. | CRC is the third most common type of cancer, but it’s the second most common cause of cancer-related death. It accounts for 10% of the world’s cancers. It’s mostly a disease of elderly, affecting those in their 60s and 70s. >90% of colorectal cancers develop from adenomatous polyps of the colon. | ||
Screening is important to reduce the incidence of CRC. In Europe, screening programs for CRC are in development or recently launched. Generally, people above 50/55 should be screened with colonoscopy, or alternatively, with a faecal occult blood test. | Screening is important to reduce the incidence of CRC. In Europe, screening programs for CRC are in development or recently launched. Generally, people above 50/55 should be screened with [[colonoscopy]], or alternatively, with a [[faecal occult blood test]]. | ||
== Etiology == | == Etiology == | ||
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* Older age | * Older age | ||
* Red meat | * Red meat | ||
* Alcohol | * [[Alcohol]] | ||
* Processed meat | * Processed meat | ||
* Obesity | * [[Obesity]] | ||
* Smoking | * [[Smoking]] | ||
* Lack of physical activity | * Lack of physical activity | ||
NSAIDs on the other hand, especially aspirin, | [[NSAID|NSAIDs]] on the other hand, especially aspirin, may be protective against colorectal cancers as they inhibit the enzyme cyclooxygenase-2 (<abbr>COX</abbr>-2), which is highly expressed in the carcinomas. | ||
We can distinguish multiple types of CRC according to cause: | We can distinguish multiple types of CRC according to cause: | ||
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* Sporadic CRC (95% of cases) | * Sporadic CRC (95% of cases) | ||
* Hereditary CRC | * Hereditary CRC | ||
** | ** Hereditary non-polyposis colorectal cancer | ||
** | ** Familial adenomatous polyposis | ||
* IBD-associated CRC | * [[Inflammatory bowel disease (Crohn disease and ulcerative colitis)|IBD]]-associated CRC | ||
== Pathology == | == Pathology == | ||
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== Clinical features == | == Clinical features == | ||
The most important symptoms are those of lower GI bleeding (haematochezia, melena, iron-deficiency anaemia) or altered bowel habits. Altered bowel habits is more common for left-sided cancers compared to right-sided, due to the smaller lumen of the left-sided colon. Abdominal pain is also a common symptom. Rectal cancers cause tenesmus and incomplete defecation. | The most important symptoms are those of lower [[Gastrointestinal bleeding|GI bleeding]] (haematochezia, melena, [[Iron deficiency anaemia|iron-deficiency anaemia]]) or altered bowel habits. Altered bowel habits is more common for left-sided cancers compared to right-sided, due to the smaller lumen of the left-sided colon. Alternating diarrhoea and constipation is a common sign. Abdominal pain is also a common symptom. Rectal cancers cause tenesmus and incomplete defecation. | ||
Metastases are present at presentation in 20% of cases. Distal rectal cancers may be palpated on DRE. | Metastases are present at presentation in 20% of cases. Distal rectal cancers may be palpated on DRE. | ||
== Diagnosis and evaluation == | == Diagnosis and evaluation == | ||
Colonoscopy is the gold standard investigation for CRC, as it not only allows for diagnosis but also for biopsy (and sometimes complete removal) of the lesion. If a suspicious lesion is found, the whole colon must still be examined, because of the relatively high chance of synchronous primary tumours. | [[Colonoscopy]] is the gold standard investigation for CRC, as it not only allows for diagnosis but also for biopsy (and sometimes complete removal) of the lesion. If a suspicious lesion is found, the whole colon must still be examined, because of the relatively high chance of synchronous primary tumours. | ||
CT colonography (virtual colonoscopy) is an alternative to colonoscopy, but it does not allow for biopsy or removal. | [[CT]] colonography (virtual colonoscopy) is an alternative to colonoscopy, but it does not allow for biopsy or removal. | ||
Once the diagnosis of colon cancer has been made, a CT of the chest, abdomen, and pelvis is required for staging. For rectal cancers, MRI is used. | Once the diagnosis of colon cancer has been made, a CT of the chest, abdomen, and pelvis is required for staging. For rectal cancers, MRI is used. | ||
CEA should be measured upon diagnosis. Elevated CEA is associated with a worse prognosis, and CEA which doesn’t normalise postoperatively is indicative of persistent disease. | [[CEA]] should be measured upon diagnosis. Elevated CEA is associated with a worse prognosis, and CEA which doesn’t normalise postoperatively is indicative of persistent disease. | ||
== Treatment == | == Treatment == | ||
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== Screening == | == Screening == | ||
Screening is important to reduce the incidence of CRC, as most CRCs develop from adenomatous polyps which take years to develop into cancer. In Europe, screening programs for CRC are in development or recently launched. Generally, people above 50/55 should be screened with colonoscopy, or alternatively, with a faecal occult blood test. | Screening is important to reduce the incidence of CRC, as most CRCs develop from adenomatous polyps which take years to develop into cancer. In Europe, screening programs for CRC are in development or recently launched. Generally, people above 50/55 should be screened with [[colonoscopy]], or alternatively, with a [[faecal occult blood test]]. | ||
[[Category:Gastroenterology]] | [[Category:Gastroenterology]] | ||
[[Category:Gastrointestinal surgery]] | [[Category:Gastrointestinal surgery]] | ||