Colorectal cancer

Question 1

Describe colorectal neoplasia

Answer 1

Benign - adenoma

Malignant - adenocarcinoma

Question 2

Describe colorectal polyps

Answer 2

inflammatory
hamartomatous
metaplastic
neoplastic (adenoma)

Question 3

Genes associated with cancer

Answer 3

Oncogenes - excess cell growth and division

Tumour suppressor genes - mutated allow cell growth and division (loss of function)

Question 4

Microscopic appearances of colorectal cancer

Answer 4

Polypoidal
ulcerative
annular

Question 5

Histology of Colorectal neoplasia

Answer 5

Adenomas - tubular, villous

Question 6

Adenocarcinoma

Answer 6

well/moderately/poor differentiated

Question 7

Pathology staging

Answer 7

Dukes - A, B, C, D
TNM
T= tumour
N= (lymph) nodes
M= metastases

Question 8

What are the T stages?

Answer 8

T1 = submucosa only
T2 = into muscle 
T3 = through muscle
T4 = adjacent structures (including peritoneum)

Question 9

What are the N stages?

Answer 9

N0 = no lymph nodes
N1 = 3 nodes involved

Question 10

What are the M stages?

Answer 10

M0 = no distant metastases 
M1 = distant metastases

Question 11

Describe the spread of colorectal cancer

Answer 11

Local - adjacent structures
Lymphatic - pericolic/perivascular nodes
Blood - liver and lungs
transcoelomic - peritoneal cavity

Question 12

What is the Aetiology of colorectal cancer?

Answer 12

Environment, genetic and predisposing conditions

Question 13

How does LKB1 work?

Answer 13

LKB1 and Exercise –> AMPK –> glucose uptake by muscle + decreased cell turnover

Question 14

Describe FAP and HNPCC

Answer 14

FAP - mutation in APC gene, 1-3% of all colorectal cancer

HNPCC - mutation in DNA mismatch repair gene, 5-10% of all colorectal cancer

Question 15

What are the predisposing factors?

Answer 15

Adenomatous polyps
Ulcerative colitis
Crohn’s disease

Question 16

What are symptoms of colorectal cancer?

Answer 16

Anaemia
Pain
Bowel habit change
rectal bleeding
tenesmus

Question 17

Clinical findigns of colorectal cancer?

Answer 17

general - anaemia, cachexia, lymphadenopathy
Abdomen - mass, hepatomegaly, distension
Rectum - mass, blood

Question 18

What investigations are used to diagnose colorectal cancer?

Answer 18

Barium enema
CT colography
Sigmoidoscopy
colonoscopy

Question 19

What is FOBT?

Answer 19

detects around 70% of cancers
not useful in symptomatic patient
used in screening

Question 20

What staging investigations are used?

Answer 20

Lungs - CXR or CT
Liver - ultrasound or CT
Primary rectal cancer - CT or MRI

Question 21

What emergency presentations may arise for colorectal cancer ?

Answer 21

Obstruction - distension, constipation, pain and vomiting

bleeding and perforation

Question 22

What treatments are there for obstructions

Answer 22

Colostomy alone
Resection + colostomy
stenting

Question 23

Treatments of colorectal cancer

Answer 23

Surgery
radiotherapy
chemotherapy

Question 24

Surgery for colonic cancer

Answer 24

Right hemicolectomy 
extended right hemicolectomy 
transverse colectomy 
left hemicolectomy
sigmoid colectomy 
subtotal colectomy

Question 25

Surgery for rectal cancer

Answer 25

Abdomino-perineal excision
anterior resection
(local excision)

Question 26

Radiotherapy for rectal cancer

Answer 26

Adjuvant - pre/post operative
reduces local recurrence after rectal excision
palliative - inoperable primary rectal cancer
recurrent rectal cancer

Question 27

Chemotherapy for colorectal cancer

Answer 27

5-fluorouracil (5-FU)
Adjuvant for stage C - 5/-10% improvement in survival
For advanced disease - medial survival advantage of ~5 months
new drugs - oxaliplatin, irinotecan
biological agents -cetuximab, bemab

Question 28

Colorectal improved survival chances

Answer 28

diet and lifestyle
awareness and screening
high quality surgeon
appropriate use of RT and chemo
new agents for advanced disease