Colorectal Cancer

Question 1

Define

Answer 1

Malignant adenocarcinoma of the large bowel.

60% in the sigmoid and rectum
30% in the descending colon
10% in the rest of the colon

Question 2

What is the staging used in colorectal carcinoma?

Answer 2

DUKES STAGING.

A- confined to the muscularis mucosae. 93% 5 year survival
B- extension beyond the muscularis mucosae. 77% 5 year survival
C- regional lymph node involvement. 48% 5 year survival
D- metastasis. 6.6% 5 year survival

Question 3

Aetiology

Answer 3

Genetic and environmental

Change from normal bowel epithelium to cancerous e.g. APC to COX 2 leading to an over expression of KRAS and P53.

The familial conditions can increase rates - FAP and HNPCC

Question 4

Risk factors:

Answer 4

Family history 
Previous colorectal cancer 
IBD
Smoking 
Western diet (red meat, alcohol and low fibre) 
Colorectal polyps

Question 5

Symptoms of a right sides tumour:

Answer 5

Presents later

Anaemia

Weight loss

Non-specific malaise

Rarely lower abdo pain

Question 6

Symptoms of a left sided tumour:

Answer 6

May be asymp as early presentation.

Change in bowel habit

Rectal bleeding (faeces with blood or mucous)

Tenesmus

Question 7

Why are 20% of tumours an emergency?

Answer 7

Lead to large bowel obstruction

Haemorrhage

Peritonitis

Question 8

Signs

Answer 8

Signs of anaemia

Abdo mass

If metastatic
Hepatosplenomengaly
Ascites (shifting dullness)

Low rectal tumours are palpable on DRE

Question 9

Investigations

Answer 9

FBC (anaemia), LFTs and Tumour markers (CEA)

Stools - FOBT

Sigmoid and colonoscopy

Double contrast enema (show apple core strictures)

Abdominal us for hepatic metastasis

Contrast CT for staging

Question 10

Epidemiology:

Answer 10

2nd most common killer in the west

3rd most common cancer in the UK and the 2nd biggest killer

Average age of presentation = 60-65