Colorectal Carcinoma

Question 1

What are the different types of colorectal tumours?

Answer 1

• Majority are adenocarcinomas.
• Other epithelial tumours include neuroendocrine, squamous cell, metastatic.
• Non epithelial tumours such as gastro-intestinal stromal tumours (GISTs) or melanoma/lymphomas.

Question 2

What is the adenocarcinoma sequence

Answer 2

• Process of the development of an adenocarcinoma. Occurs due to accumulation of genetic mutations. Early mutatations include APC and KRAS mutations. In later stages numerous mutations occur such as p53 or PIK3

Question 3

What are some of the risk factors for colorectal carcinoma?

Answer 3

• Size, number and villous adenomas.
• History of IBD (especial UC),
• Increasing age,
• Obesity,
• Sedentary lifestyle,
• High fat and low fibre diet,
• Smoking and alcohol use
• Family history

Question 4

What are the different hereditary risk factors for colorectal carcinoma?

Answer 4

• Familial Adenomatous Polyposis (APC mutation)
• Lynch Syndrome (previously HNPCC - mismatch repair defect)

Question 5

What is a polyp?

Answer 5

Exophytic protuberant growth.

Question 6

Name examples of colorectal polyps

Answer 6

Hamartomatous polyps, inflammatory polyps, hyperplastic polyps and adenomas. All of which are dysplastic by nature. (dysplasia = disordered growth)

Question 7

What are the different architecture types of colorectal adenomas?

Answer 7

They can be villous, tubulovillous or tubular

Question 8

What is the histological appearence of adenocarcinoma of the bowel?

Answer 8

• Can present with an ulcerated surface and irregular glands (malignant).
• Desmoplastic stroma

Question 9

How can muscular invasion be shown histologically in colorectal carcinomas?

Answer 9

With elastic H and E stain

Question 10

What staging is used in colorectal cancer?

Answer 10

TNM 8:
T1 = Invasion into submucosa.
T2 = Invasion into muscularis propria (not through it).
T3 = Invasion through muscularis propria into sub serosa.
T4 = Invasion of peritoneum (a) or other organs (b)
N0 = no lymphnode mets
N1 = 1-3 LN mets
N2 = 4+ regional LN mets
M0 = no distant mets
M1 = distant mets

Question 11

What are the methods for improving early detection of bowel cancer?

Answer 11

• Bowel cancer screening = qFIT ever 2 years for patients over 50.
• Patient education of symptoms eg, PR bleeding and a change in bowel habit.