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Common Colorectal Cancer exam questions for medical finals, OSCEs and MRCP PACES

 

Question 1.

What are complications of colon cancer?

  • Local
    • Obstruction
    • Perforation
    • Bleeding (and/or iron deficiency anaemia)
    • Colovesical fistula
  • Distant
    • Metastasis

Question 2.

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

Question 3.

What are the initial investigations used to diagnose colon cancer?

  • Bloods
    • FBC, U&E, LFT, Calcium
    • Clotting, group and save
  • Colonoscopy
    • 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

Question 4.

What are the major risk factors for colorectal cancer?

  • Demographic risk factors
    • Age
    • 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
  • Comorbidities
    • Inflammatory bowel disease (risk increases with extent and duration of colitis)
    • Abdominal radiation
    • Immunosuppression
    • Diabetes
  • Modifiable risk factors
    • Smoking
    • Obesity
    • Processed meat
    • Alcohol

Question 5.

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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Free colon cancer revision for medical student exams, finals, OSCEs and MRCP PACES

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