Colorectal cancer

Question 1

What type of cancer is colorectal cancer?

Answer 1

Adenocarcinoma because they affect the lining of the bowel (epithelium)

Question 2

What is the significance of the APC gene in colorectal cancer?

Answer 2

Gene responsible for familial adenomatous polyposis coli (FAP)

It predisposes somebody to colorectal cancer

Question 3

What is the significance of K-RAS gene in colorectal cancer?

Answer 3

When there is a mutation in K-RAS, it signals too much and cells grow without being told to, which causes cancer

Along with the APC gene, they increase the risk of developing colorectal cancer

Question 4

What are some risk factors for colorectal cancer?

Answer 4

• Ulcerative colitis
• Familial Adenomatous Polyposis Coli
• Hereditary Non-Polyposis colon cancer (HNPCC, Lynch syndrome)
• Li Fraumeni (p53 mutation)
• Fibre
• Diet

Question 5

What is Hereditary non-polyposis colon cancer (HNPCC)?

Answer 5

Inherited mutation in one of the genes that form a protein complex responsible for checking accurate base pairing in new DNA (A=T, C=G)

Question 6

What is Wilsons criteria?

Answer 6

Used to decide if somebody should be screened for colorectal cancer

Question 7

What are the 2 different approaches to familial predisposition of colorectal cancer?

Answer 7

• Mismatch repair deficient (i.e. like HNPCC)
  Right sided, Large tumours with late metastases (T4N0)
  BRAF mutations worsen prognosis
• Mismatch repair proficient (i.e. like FAP)
  Polyp > cancer progression
  Left sided / Rectal
  Males > Females
  KRAS mutations frequent

Question 8

What is Duke’s criteria?

Answer 8

Used to stage colorectal cancer

-Dukes A: invasion into but not through the bowel wall (90% 5 year survival)
-Dukes B: invasion through the bowel wall but not involving lymph nodes (70% 5 year survival)
-Dukes C: involvement of lymph nodes (30% 5 year survival)
-Dukes D: widespread metastases

Question 9

What are the different types of colorectal cancer and how are they treated?

Answer 9

• Colon: treated with surgery and adjuvant chemotherapy if node positive
• Rectal: treated with MRI staging and neoadjuvant chemo/radio therapy. Much more complex than colon
• Oligometastatic disease: staged with MRI/PET and treated with removal of the metastasis
• Widespread metastatic disease: no treatment. palliative chemotherapy and supportive care is offered

Question 10

What are some methods of reducing recurrence of rectal cancer?

Answer 10

Total mesorectal excision and pre-operative radiotherapy

Question 11

What is meant by the right side of the colon?

Answer 11

The ascending colon

Question 12

How long does it take for the liver to regenerate?

Answer 12

3 months after resection

Question 13

What is the combination of chemotherapy used for metastatic colorectal cancer?

Answer 13

5-Fluorouracil (Capecitabine) + Oxaliplatin / Irinotecan

But it only prolongs life, metastatic adenocarcinomas are palliative

Question 14

What is Capecitabine?

Answer 14

An oral chemotherapy used for colorectal cancer

Must be stopped if patient feel unwell because it can cause things like angina

Question 15

Name some targeted agents for colorectal cancer

Answer 15

• Cetuximab is anti-EGFR (epidermal growth factor receptor)
  EGFR: regulating cell proliferation, survival, differentiation and migration
• Bevacizumab is anti-VEGF (Vascular endothelial growth factor)
  VEGF: responsible for angiogenesis