Colorectal Cancer

Question 1

Rank the most common sites for colorectal cancer.

Answer 1

Rectum: 27%
Sigmoid colon: 20%
Caecum: 14%
Rectosigmoid junction: 7%
Asc. colon: 7%
Transverse colon: 5%
Desc. colon: 3%
Hepatic flexure: 3%
Splenic flexure: 2%
Anus: 2% 
Appendix: 1%

Question 2

Describe the aetiology of colorectal cancer.

Answer 2

2nd most common cancer
Colon: female>male, Rectum: male>female
Median age = 72yrs (6% below 40yrs)
APC gene —> FAP

Question 3

What are the signs and symptoms of colon cancer?

Answer 3

• vague ill health
• acute/chronic obstruction
• perforation
• left-sided: rectal bleeding —> anaemia
• right-sided: melaena —> anaemia
• tenesmus
• diarrhoea (liquid moves past obstruction and irritation of bowel causes fluid loss)
• pain (rare)

Question 4

What are the signs and symptoms of rectal cancer?

Answer 4

• rectal bleeding
• incomplete evacuation —> urgency & change in bowel habit (diarrhoea)
• tenesmus
• colic
• root pain (rare)

Question 5

Reminder: define tenesmus.

Answer 5

Painful sensation of need to defecate with incomplete evacuation, urgency, and desire to strain

Pathognomonic of rectal cancer

Question 6

What investigations are appropriate for colorectal cancer?

Answer 6

IMAGING:

• CT scan: thorax/abdo/pelvis = “apple-core” strictures
• DRE
• MRI pelvis

FUNCTIONAL:
- flexible sigmoidoscopy

Question 7

Reminder: define an ulcer.

Answer 7

Persistent non-healing break in epithelium/endothelium

Question 8

Reminder: define metaplasia. How does it differ from neoplasia?

Answer 8

Change from one cell line to another

+ differentiation = neoplasia

Question 9

What is the staging system for colorectal cancer?

Answer 9

Dukes' staging 
A = confined to muscle 
B = through muscle 
C = into lymph nodes
- C1 = 5 lymph nodes 
D = distant metastases 

note: the larger the polyp, the greater the risk of malignant transformation

Question 10

What is the management of colorectal cancer?

Answer 10

Colon: hemicolectomy
Rectum: anterior resection if >5cm from anus (avoid damaging sacral plexus), abdomino-perineal resection with end colostomy if