Common Colorectal Cancer exam questions for medical finals, OSCEs and MRCP PACES
What are complications of colon cancer?
- Bleeding (and/or iron deficiency anaemia)
- Colovesical fistula
Other than surgery, what treatment would you consider for local colorectal cancer?
- Adjuvant oxaliplatin-based chemotherapy should be given in stage III (node positive) disease, for six months.
- e.g. oxaliplatin plus 5-FU, or oxaliplatin plus capecitabine
- Rectal cancer should be treated with neoadjuvant chemoradiotherapy if locally invasive or node positive
- All other rectal cancer of stage II or higher should be treated with chemoradiotherapy post-operatively
What are the initial investigations used to diagnose colon cancer?
- FBC, U&E, LFT, Calcium
- Clotting, group and save
- Identifies cancers and co-incident second cancers (synchronous lesions), and obtain tissue for histology: brushings, biopsy or resection
- CT colonography may be used in those unlikely to tolerate colonoscopy
- If cancer is confirmed, further imaging for staging should be undertaken
- CT abdomen-pelvis to assess local invasion of the primary, lymphadenopathy, and hepatic metastases
- CT chest is usually undertaken, though only 10% of nodules seen are colorectal metastases
What are the major risk factors for colorectal cancer?
- Demographic risk factors
- Male sex
- Ethnicity (black people have a higher risk but this may be due to confounding variables)
- Family history
- Previous history
- Previous colorectal cancer or previous polyps >1cm exhibiting high grade dysplasia or with villous/tubulovillous histology
- Inflammatory bowel disease (risk increases with extent and duration of colitis)
- Abdominal radiation
- Modifiable risk factors
- Processed meat
What genetic disorders are associated with colorectal cancer?
- Hereditary non-polyposis colorectal cancer (HNPCC)
- Autosomal dominant, due to mutations in various mismatch repair genes and responsible for 3% of colorectal cancers
- Also increases the risk of endometrial cancer, other GI tract cancers and ovarian cancer
- Familial adenomatous polyposis (FAP)
- Autosomal dominant defect in APC gene
- Causes numerous colonic polyps in childhood and colorectal cancer by the age of 45 in 90% of patients
- MUTYH-associated polyposis
- Autosomal recessive condition which may cause polyposis and confers increased colorectal cancer risk
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