26 - Tumours of the Colon

Question 1

Neoplasm?

Answer 1

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should.

Question 2

What cancer is most common and most common cause of cancer death?

Answer 2

Colon cancers
Lung cancer (colon cancers are second)

Question 3

What type of malignancy makes up most of the malignancies in the GI tract?

Answer 3

Adenocarcinomas - these make up 70% of malignancies/cancers of the GI tract

Question 4

…. is an uncommon site for benign and malignant neoplasms

Answer 4

Small Intestine - despite its length

Question 5

The 2 major groups of the tumours of the colon are

Answer 5

Benign (mainly polyps)

Malignant (mainly adenocarcinomas)

Question 6

The adenocarcinomas of the colon typically arise on a … … …

Answer 6

Background of previous adenoma

Question 7

Adenoma?

Answer 7

Adenoma is a type of non-cancerous tumor or benign

Question 8

Adenocarcinoma?

Answer 8

a malignant tumour formed from glandular structures in epithelial tissue.

Question 9

Polyps are classed as

Answer 9

neoplastic and non-neoplastic polyps

Question 10

Polyps are

Answer 10

Polyps are benign circumscribed growths/tumors that project above the surrounding mucosa

Question 11

Require a … to determine nature and pathology

Answer 11

Biopsy

Question 12

Non-neoplastic polyps

Answer 12

Non-neoplastic polyps – benign overgrowths of mucosa that have no association with an increased risk of developing carcinoma/ don’t develop into malignancy

Question 13

Neoplastic polyps

Answer 13

Neoplastic polyps – adenomas that are benign tumors but if left have the potential to progress and develop into adenocarcinomas (need to biopsy)

Question 14

Non-neoplastic polyps can be further divided into

Answer 14

hyperplastic and inflammatory polyps

Question 15

What are the most common types of polyps?

Answer 15

Hyperplastic non-neoplastic polyps

Question 16

Hyperplastic polyps?

Answer 16

Overgrowths of normal mucosa so look like normal mucosa cells (no dysplasia or abnormality of cells)
Benign, asymptomatic and NO malignant potential
Most common
Small less than 1cm

Question 17

Inflammatory Polyps

Answer 17

REACTIVE overgrowths of the mucosa driven by cytokines released by inflammation
Seen in IBD (ulcerative colitis and Chrohn’s)
Benign

Question 18

Adenomas?

Answer 18

Adenomas are benign polyps WITH malignant potential

Question 19

What are the 3 types of adenomas and which has the highest predisposition to a malignant change and which are the largest?

Answer 19

1. tubular adenomas
2. villous adenomas
3. tubulovillous adenomas

Villous adenomas have highest predisposition to malignant change and are the largest

Question 20

What is the adenoma to carcinoma sequence

Answer 20

There is a distinct sequence and progression from a benign adenoma to malignant carcinoma by epithelial proliferation

1. Hyperproliferation
2. Small and large adenomas
3. Severely dysplastic pre-cancerous polyp
4. Adenocarcinoma
   5 Carcinoma/cancer invades mucosa through the wall of the bowel to spread to local nodes, lung etc

Question 21

Adenoma malignant risk is determined by

Answer 21

Size (larger worse - biggest risk of carcinoma progression i.e. villous)
Architecture (villous or tubular)
Degree of dysplasia

Question 22

A minimum of …. mutations in cancer causing/preventing genes are required to complete the molecular transition and dysplastic changes from normal mucosa to carcinoma

Answer 22

4-5 mutations

Question 23

Colorectal cancer makes up …. of all cancer deaths

Answer 23

15%

Second most common cause of cancer death and most common cancer in NZ

Question 24

What is the peak age of diagnosis of colorectal cancer? What if patients present earlier than this?

Answer 24

peak age 60-70

If onset younger than this consider familial cancers in the same way you do for pre-menopausal breast cancer

Question 25

Are males or females more likely to get rectal cancer

Answer 25

Males. Other colorectal cancers are similar amongst males and females

Question 26

What are risk factors for colorectal cancer

Answer 26

Environmental factors | Especially diet - high red meat, low fiber, high carbs

Question 27

Colorectal cancer is more common in

Answer 27

Undeveloped countries - suggests lifestyle disease

Question 28

Colorectal cancer has a protective factor of ... and ...

Answer 28

Aspirin and NSAIDs

Question 29

Where do colorectal cancers typically occur

Answer 29

Anywhere in the colon. Less frequently in the small intestine

Question 30

How does carcinoma differ from benign polyps?

Answer 30

Polyps are benign circumscribed mucosal overgrowths that protrude from the mucosa Cancer is larger, has ulceration, invade and have necrotic tissue

Question 31

What do colorectal cancers attempt to form in histology

Answer 31

Glandular tissue

Question 32

How do we stage colorectal cancers

Answer 32

TNM T = Extent of invasion in bowel wall N = Number of lymph nodes invaded M = metastic disease present or not

Question 33

Why is staging of cancers important

Answer 33

To determine the diagnosis, prognosis, treatment and curability of the tumor

Question 34

4 stages of cancer

Answer 34

1. Tumour only involves mucosa. No invasion into mucosal wall 2. Invasion of mucosal wall and muscle 3. Invasion/perforation through mucosal wall 4. Spread to local lymph nodes so potential for lymphatic and haematological spread (metastatic growth)

Question 35

Clinical features of colorectal cancer?

Answer 35

- abdominal pain - mucus discharge - PR bleeding - change in bowel habit - weight loss - symptoms if spread to local lymph nodes i.e. liver, lung, bone - may have bowel obstruction

Question 36

How may right sided tumours present and why

Answer 36

- asc/caecum - can present with iron deficiency anaemia due occult blood loss - don't see in stool/rectum - slow bleeding due to ulceration or lesion

Question 37

What percentage of colorectal cancers do familial/inherited cancers make up

Answer 37

5%

Question 38

What are the 2 main familial colorectal cancer syndromes?

Answer 38

1. Familial polyposis Syndrome | 2. Hereditary Non-Polyposis Colorectal Cancer

Question 39

Familial Polyposis Syndrome

Answer 39

- autosomal dominant - family of polyposis syndromes - sheets of polyps throughout large bowel with high risk of developing into adenocarcinoma - linked to APC gene - phenotype varies with the mutation

Question 40

Hereditary Non-Polyposis Colorectal Cancer (HNPCC)

Answer 40

- more common (5%) - no polyps but increase risk of progression from adenoma to adenocarcinoma - young onset/familial history - mutation in DNA mismatch repair gene