day 4 - Colorectal cancer

Question 1

types of colorectal polyp

Answer 1

Hyperplastic: non-neoplastic
Inflammatory: non-neoplastic but overlap with adenoma Adenoma: tubular. tubulovillous, villous

Question 2

malignant progression of colorectal polyps

Answer 2

normal mucosa — adenomatous polyp — adenocarcinoma
adenoma –> carcinoma sequence in < 5% but probably accounts for most colorectal carcinomas.

this sequence is the morphological corollary of the multi-step theory of neoplasia

Question 3

metastatic targets of colorectal carcinomas

Answer 3

Metastases: –> lymph nodes; portal vein –> liver

Question 4

define what a polyp is

Answer 4

A polyp: a protrusion of a circumscribed lesion into a hollow viscus

Question 5

different types of adenomatous polyp

Answer 5

dysplastic by definition, i.e. show neoplastic potential

Question 6

Definition Of Dysplasia

Answer 6

Dysplasia is a MICROSCOPIC DIAGNOSIS synonymous with intraepithelial neoplasia and is recognised by a combination of :

1. Cytological atypia
2. Architectural disorder

Question 7

difference in malignant potential of adenomatous polyps based on size

Answer 7

74% of adenoma are 2 cm show malignant change

Question 8

Familial Polyposis Syndromes

Answer 8

familial adenomatous polyposis (FAP)
hereditary nonpolyposis colon cancer (HNPCC)
juvenile polyposis

Question 9

Familial Adenomatous Polyposis (FAP) details

Answer 9

autosomal dominant

Question 10

Hereditary Non - Polyposis Colorectal Cancer (HNPCC)

details

Answer 10

autosomal dominant - DNA mismatch repair genes

Mutational pathway different from that operating in common colorectal adenocarcinomas

Question 11

what is the duke’s staging system?

Answer 11

The Dukes staging system is a classification system for colorectal cancer. This system is now mainly of historical interest as it has largely been replaced by the TNM staging system. It is not recommended for clinical practice.

Dukes A - invasion into but not through the bowel wall (90% 5 year survival)
Dukes B - invasion through the bowel wall but not involving lymph nodes (70% 5 year survival)
Dukes C - involvement of lymph nodes(30% 5-y survival)
Dukes D - widespread metastases

Question 12

TNM staging system

Answer 12

The number of Ts Ns and Ms depend on the tumour/site but in general:

T: Tumour

Tx: primary tumour cannot be assessed
T0: no evidence of primary tumour
Tis: carcinoma in situ
T1: site/tumour specific, generally small
T2: site/tumour specific
T3: site/tumour specific, generally large
T4: site/tumour specific but usually refers to direct extension into adjacent organs/tissues.

N: Nodes

Nx: nodes cannot be assessed
N0: no evidence of nodal involvement
N1: site/tumour specific
N2: site/tumour specific
N3: site/tumour specific

M: Metastases

Mx: presence of metastases cannot be assessed
M0: no evidence of metastases
M1: distant metastases present
Other descriptors

Suffix

m: multiple primary tumours, e.g. T2(m) or T2(5)
In addition TNMs can be combined into stages I , II , III, IV,

Question 13

Colorectal Cancer Screening

Answer 13

WHY? – regular screening can reduce the no. of deaths by 16%
AIM? – detect cancers at an early stage when treatment is more effective
HOW? – FOB tests
WHO? – all men and women between 60 and 69
HOW OFTEN? – every 2 years

Those over the age of 70 can phone up and request a testing kit

Question 14

How Does FOB test work?

Answer 14

• Polyps and Bowel cancers sometimes bleed
• Faecal Occult Blood (FOB) detects microscopic amounts of blood in the faeces


Question 15

What Happens to Positive FOB Tests?

Answer 15

• 2 in 100 tests will be positive – referred for a colonoscopy
• 4 in 100 tests will have an unclear test meaning there is a suggestion of traces of blood and these can be repeated