Sardelic's pop quiz

Question 1

What are the major risk factors for colorectal cancer?

Answer 1

• Increasing age (>60yrs)
• Western diet (low fibre, high fat)
• Ulcerative colitis
• Polyposis syndromes
  
  • Familial adenomatous polyposis
  • Peutz-jeghers syndrome – hamartomatous polyps
• Hereditary non-polyposis colorectal cancer (HNPCC)
• Central obesity
• Physical activity
• EtOH
• Family hx of colorectal cancer with young age at diagnosis
• Hx of polyps =/- adenomas

Question 2

What method is used for population screening for Colorectal cancer in Australia?

Answer 2

Faecal occult blood test

• 50-74yrs
• For low-risk people with no symptoms
• Screening kits are mailed to residents
• 2 yearly – kits received 6 months within birthday at 50, 52, 54, … ,

Question 3

What is neoadjuvant therapy for rectal cancer?

Answer 3

Chemoradiotherapy to shrink the tumour to improve the chances of surgical removal.

• Offered to Dukes C cancers (stage III)
• Chemoradiotherapy in rectal tumours tethered in the pelvis
• Radiotherapy where rectal cancers extend through the bowel wall anteriorly to reduce local recurrence
• Chemotherapy in large bowel cancer – 5-fluorouracil (5-FU) is the primary agent, given in combination with bimodulator folinic acid.

Question 4

what are the common sites that metastatic disease from a colorectal primary are found?

Answer 4

• Liver most common
• Lungs 2^nd most common
• Bone
• Peritoneum

Question 5

What are the treatment options for a liver metastases from a colorectal primary?

Answer 5

• Majority of patients cannot be cured and intent of treatment is usually palliative
• If mets are localized to one anatomical lobe it may be resected. – partial hepatectomy
  
  • PET scan to esclude extra-hapatic metastases
  • Exclusion criteria
    
    • Extrahepatic metastases
    • Radiographic evidence of involvement of the common hepatic artery, common bile duct or portal vein
    • Extensive liver involvement (>70%, or >6 segments, or involvement of all 3 hepatic veins)
    • Inadequate predicted post-resection functional hepatic reserve
    • Patient not fit for surgery
• Oral dexamethasone may temporarily reduce metastatic tissue edema and relieve symptoms
• Neoadjuvant chemotherapy to allow a tumour to become resectable
• Radiofrequency ablation
• Hepatic intra-arterial chemotherapy
• Radiotherapy

Question 6

What is the adenoma-carcinoma sequence?

Answer 6

• Adenoma-carcinoma sequence refers to a stepwise pattern of mutation in a cell or group of cells that results in cancer
• Mutations include
  
  • Activation of oncogenes from proto-oncogenes (e.g. K-RAS)
  • Inactivation of tumour suppressor genes (e.g. p53, APC)
• The classic adenoma-carcinoma sequence accounts for 80% of sporadic colon tumours and typically includes mutation of APC early in the process
• Supporting evidence of this model [Uptodate]
  
  • Early carcinomas are frequently seen within large adenomatous polyps, and areas of adenomatous change can often be found surrounding human CRCs
  • Adenomas and carcinomas are found in similar distributions throughout the large bowel, and adenomas are typically observed 10 to 15 years prior to the onset of cancer in both sporadic and familial cases.
  • In animal models, adenomas develop before carcinomas, and carcinomas develop exclusively in adenomatous tissue
  • The ability to reduce the incidence of CRC through the removal of polyp shas been shown in controlled trials in humans.