Colorectal Cancer

Question 1

What are hyperplastic adenomas?

Answer 1

• Composed of cells that look like they have more mucin in them than normal

Question 2

What are Gastrointestinal Stromal Tumours (GIST)?

Answer 2

• Spindle cell tumour derived from the interstitial cells of Cajal
• Arise more often in upper GI tract than lower GI tract
• Risk of malignant behaviour depends on mitotic rate and size, but exact criteria varies from site to site
• Majority have abnormalities of tyrosine kinase receptor – can be targeted by Imatinib
• C-kit (CD 117) stain identifies upregulation of tyrosine kinase receptors and predicts drug response

Question 3

What is Familial Adenomatous Polyposos (FAP)?

Answer 3

• APC (AD), via phosphorylation of β-catenin, APC protein controls activation of a variety of transcription factors within cells. This in turn affecting the expression of a variety of genes that can change the proliferation and differentiation of cells
• MUTYH (AR)

Question 4

What is Lynch Syndrome?

Answer 4

• HNPCC gene
• Adenocarcinoma sequence progresses at a faster rate in these patients
• Loss of function of DNAMMR genes results in more rapid development of genetic abnormalities
• Affected genes include MLH1, MSH2, MSH6 and PMS2

Question 5

Presentation of colorectal cancer

Answer 5

• Change in bowel habit
• Weight loss
• PR bleeding
• Tenesmus (feeling of full rectum even after opening bowels)
• IDA
• Bowel obstruction

NB - Most common type is adenocarcinoma.

Question 6

Investigation of colorectal cancer

Answer 6

• Colonscopy - gold standard, visualise lesion, can include biopsy
• CT colonography - consider if patient less fit for colonoscopy
• CT CAP for staging
• Carcinoembryonic Antigen (CEA) - tumour marker for bowel cancer, useful in predicting relapse

Question 7

Dukes classification of colorectal cancer

Answer 7

• A - confined to mucosa and part of the muscle of the bowel wall
• B - extending through the muscle of the bowel wall
• C - lymph node involvement
• D - metastatic disease

Question 8

Management of colorectal cancer

Answer 8

• MDT input
• Surgical resection
• Chemotherapy
• Radiotherapy
• Palliation

Question 9

Covering loop ileostomy

Answer 9

• A temporary ileostomy created to protect a distal anastomosis
• Typically left for 6-8 weeks to allow healing of the anastomosis, after which is it reversed
• “Loop” refers to it being the two ends (proximal and distal) of a section of small bowel being brought out onto skin
• Proximal end (the productive side) has turned inside out to form a spout to protect the surrounding skin
• Usually located lower right side of abdomen

Question 10

Right hemicolectomy

Answer 10

Question 11

Left hemicolectomy

Answer 11

Question 12

Sigmoid Colectomy

Answer 12

Question 13

Anterior Resection

Answer 13

Question 14

Abdominoperineal Resection

Answer 14

Question 15

Follow-up for curative treatment of coloractal cancer

Answer 15

• CT CAP at 1 and 2 or 3 years
• Colonoscopy at 1 and 5 years
• CEA 6 monthly for 3 years
• Thereafter based on local policy