26 - Tumours of the Colon Flashcards

1
Q

Neoplasm?

A

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

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2
Q

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

A
Colon cancers
Lung cancer (colon cancers are second)
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3
Q

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

A

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

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4
Q

…. is an uncommon site for benign and malignant neoplasms

A

Small Intestine - despite its length

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5
Q

The 2 major groups of the tumours of the colon are

A

Benign (mainly polyps)

Malignant (mainly adenocarcinomas)

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6
Q

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

A

Background of previous adenoma

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7
Q

Adenoma?

A

Adenoma is a type of non-cancerous tumor or benign

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8
Q

Adenocarcinoma?

A

a malignant tumour formed from glandular structures in epithelial tissue.

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9
Q

Polyps are classed as

A

neoplastic and non-neoplastic polyps

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10
Q

Polyps are

A

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

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11
Q

Require a … to determine nature and pathology

A

Biopsy

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12
Q

Non-neoplastic polyps

A

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

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13
Q

Neoplastic polyps

A

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

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14
Q

Non-neoplastic polyps can be further divided into

A

hyperplastic and inflammatory polyps

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15
Q

What are the most common types of polyps?

A

Hyperplastic non-neoplastic polyps

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16
Q

Hyperplastic polyps?

A

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

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17
Q

Inflammatory Polyps

A

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

18
Q

Adenomas?

A

Adenomas are benign polyps WITH malignant potential

19
Q

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

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

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

20
Q

What is the adenoma to carcinoma sequence

A

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
21
Q

Adenoma malignant risk is determined by

A

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

22
Q

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

A

4-5 mutations

23
Q

Colorectal cancer makes up …. of all cancer deaths

A

15%

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

24
Q

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

A

peak age 60-70

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

25
Q

Are males or females more likely to get rectal cancer

A

Males. Other colorectal cancers are similar amongst males and females

26
Q

What are risk factors for colorectal cancer

A

Environmental factors

Especially diet - high red meat, low fiber, high carbs

27
Q

Colorectal cancer is more common in

A

Undeveloped countries - suggests lifestyle disease

28
Q

Colorectal cancer has a protective factor of … and …

A

Aspirin and NSAIDs

29
Q

Where do colorectal cancers typically occur

A

Anywhere in the colon. Less frequently in the small intestine

30
Q

How does carcinoma differ from benign polyps?

A

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

31
Q

What do colorectal cancers attempt to form in histology

A

Glandular tissue

32
Q

How do we stage colorectal cancers

A

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

33
Q

Why is staging of cancers important

A

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

34
Q

4 stages of cancer

A
  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)
35
Q

Clinical features of colorectal cancer?

A
  • 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
36
Q

How may right sided tumours present and why

A
  • 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
37
Q

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

A

5%

38
Q

What are the 2 main familial colorectal cancer syndromes?

A
  1. Familial polyposis Syndrome

2. Hereditary Non-Polyposis Colorectal Cancer

39
Q

Familial Polyposis Syndrome

A
  • 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
40
Q

Hereditary Non-Polyposis Colorectal Cancer (HNPCC)

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