Colorectal Cancer

Question 1

What is the relevant epidemiology of colorectal cancer?

Answer 1

4th most common cause of cancer in the UK
2nd larges cause of cancer related deaths
Peak incidence between 65-74yrs of age

Question 2

What site in the colon is colorectal cancer most common?

Answer 2

Rectum
Sigmoid
Ceaecum
Ascending

Question 3

What is the basic pathophysiology underpinning colorectal cancer?

Answer 3

1. 85% have chromosomal instability - progressice accumulation of mutations in oncogenes and TSGs, results in slow transformations are adenomas into carcinomas. Commonly seen in FAP.
2. 15% develop through microsatellite instability - due to methylation or mutations in repair genes (MMR genes, MLH1 or MSH2) seen in Lynch syndrome.

Question 4

What are some commonly mutated genes in colorectal cancer?

Answer 4

Oncogenes - KRAS
TSGs - APC, TP53, MLH1 or MSH2

Question 5

What is Lynch syndrome?

Answer 5

Hereditary non-polyposis colorectal cancer
Most common cause of hereditary colorectal cancer
Increased risk of lots of cancers before 50yrs, including endometerial, stomach, liver, kidney and brain.
Autosomal dominant mutation in DNA mismatch repair genes - results in increased risk of mutation in driver genes - few polyps each with a high chance of becoming cancerous.

Question 6

What bowel screening programe exists with the UK?

Answer 6

Everyone 60 to 74yrs reg with GP in Englands is automatically invited to screening every 2 yrs
FIT test
If have lynch syndrome offered colonoscopy every 2 years/

Question 7

What happens in colorectal cancer screening after a positive FIT test?

Answer 7

Offered an appt with the surgical team for possible colonscopy.

Question 8

What are the key clinical features of colorectal cancer?

Answer 8

Weight loss
Fever
Night sweats
Fatigue
Abdominal discomofrt (Can present similar to diverticulitis especially in carcinoma of rectosigmoid or descending colon)

Question 9

What are the key clinical features of a right sides colon cancer?

Answer 9

Occult bleeding or melena
Manifestation of iron deficient anaemia (due to chronic bleeding)
Iron defieiciny anarmia in men >50yrs and postmenopausal women should raise suspicions for colorectal cancer

Question 10

What are the key clinical features of a left sided colon cancer?

Answer 10

Changes in bowel habits
Colicky abdominal pain (due to obstruction)

Question 11

What are the key clinical features of rectal cancer?

Answer 11

Fresh PR bleeding
Reduced Stool caliver (pencil-shaped stool)
Rectal pain
Tenesmus

Question 12

What investigations should be ordered for suspected colorectal cancer?

Answer 12

Bloods:
FBc - anaemia
Acute Phase Reactants - inflammation
CEA - prognostic not screening
AFP - tumour marker - norm in liver cancer or germline cancers
Stool sample for FIT testing
DRE
Flexible sigmoidoscopy
Colonscopy

Question 13

What are the two different staging systems used for colorectal cancer?

Answer 13

Dukes Staging
TMN staging

Question 14

What are the different stages of colorectal cancer by Dukes staging methods?

Answer 14

A - cancer confined to innermost lining of GIT
B - cancer grown into muscle layer of wall of GIT
C - spread to lymph nodes surrounding the colon/rectum
D - metastasixed to other body parts.

Question 15

At what stage of colorectal cancer are most patients diagnosed? And how does this affect their five year survival?
(Dukes Staging)

Answer 15

A - 10% patietns - 80% survival
B - 35% patients - 65% survival
C - 25% patietns - 45% survival
D - 30% patients - only 15% survive up to 2years.

Question 16

Explain how to calculate TNM scores for colorectal cancer

Answer 16

T - size and invasion of primary tumour into nearby tissue, 1 = submucosa, 2 = muscularis propia, 3 = beyond muscularis propia, 4 = invades adjacent organs
N - regional lymph node involvement, 0=no, 1 = any
M- distant metastasis, 0 = no, 1 = any

Question 17

How does the stage of colorectal cancer relate to the TNM stage?

Answer 17

Stage 0 = alls cores zero
Stage 1 = cancer that is localised, just into the muscularis propia
Stage 2 = cancer invades through the muscularis propia, no lymph node involvement
Stage 3 = any T with lymph node involvement
Stage 4 = distant metastasis, any T/N.

Question 18

What factors affect the choice of surgical treatment for a colorectal cancer?

Answer 18

Location and spread of cancer (other organs and nodes)
Blood supply
Lymphatic drainage
Patient fitness
Patient choice.

Question 19

Identify what typical tumour location in the colon leads to what type of bowel resection.

Answer 19

Cecum = right hemicolectomy
Hepatic flexure = extended right hemicolectomy
Transver colon = transverse colectomy
Descending colon = left hemicolectomy
Sigmoid colon = sigmoidectomy

Question 20

When might other surgical procedures (not resection or colonoscopy) be indicated in colorectal cancer?

Answer 20

Metastatic disease
Presents as bowel obstruction or palliative care - colon stenting
Defunctioning stoma - temporary, to prevent anastamotic leak after surgery.

Question 21

What are some different types of stomas?

Answer 21

Right colostomy
Ileostomy
Transverse coloestomy
Jejunostomy
Left colostomy

Question 22

What is the relevant terminaology relating to a stoma/colostomy/ileostomy?

Answer 22

Stoma - the hole/opening in the skin
Colostomy = the bad if opening in large intestine
Ileostomy = the bad if opening in the small intestine

Question 23

What is meant by an end stoma?

Answer 23

Exteriorization of the proximal end of the bowel
Distal end if sutured or stapled closed and remains as a blind pouch in the abdomen.

Question 24

What is meant by a loop stoma?

Answer 24

Protects distally located parts of the intestine
Entire loop of bowel is brought outside, then cut and exteriozied.
Is easily joined back together.
Both distal and proximal section have a common stoma

Question 25

What is a double barrerl stoma?

Answer 25

Results in two stoma sites, often in close proximity to each other
Bowel is cut in half, both proximal and distal sections are used to create a stoma
This tends not to be reversible.

Question 26

What is the difference between adjuvant and neo-adjuvant therapy?

Answer 26

Adjuvant - given at same time or after
Neo-adjuvant - given before

Question 27

What are the five year survival rates after surgical resection only treatment for colorectal cancer?

Answer 27

99% for stage 1
Around 75% for stage 2
Around 55% for stage 3.