For introduction, epidemiology, etiology, and pathomechanism, see the corresponding pathology 2 topic.
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.
Metastases are present at presentation in 20% of cases.
Distal rectal cancers may be palpated on DRE.
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.
CT colonography 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.
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.
The gold standard treatment for CRC is radical surgery. Options include left or right hemicolectomy, sigmoid colectomy, or total or subtotal colectomy. This may be performed open, laparoscopically, robot-assisted, etc. At least 12 regional lymph nodes must be removed for proper surgical staging.
Rectal cancer is treated with total mesorectal excision (TME) in most cases, or more modern techniques like transanal endoscopic microsurgery (TEM).
CRC is one of the few cancers in which M1 cancers can be cured, as surgical resection of liver and/or lung metastases may allow for cure.
Surgery may also be used palliatively, either by resection, bypass operation, stoma formation, or by stenting.
B12. Diverticulosis and diverticulitis
B18. Malignant tumors of the stomach