Colorectal Cancer Flashcards

1
Q

Two categories of colorectal neoplasia?

A

Benign (adenoma)

Malignant (adenocarcinoma)

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2
Q

Types of colorectal polyps?

A

Inflammatory, e.g: in IBD

Hamartomatous are juvenile polyps

Metaplastic (change in mature mucosal type)

Neoplastic (ADENOMAS)

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3
Q

2 types of neoplastic polyps (adenomas) and which is assoc. with an increased malignancy risk?

A

Tubular - formation of glands and tubules

Villous - formation of villi (increased risk of malignancy)

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4
Q

Explain the steps in the adenoma-carcinoma sequence

A
  1. Small adenoma forms when there is the 1st mutation, usually in the APC gene (adenomatous polyposis coli)
  2. Large adenoma forms when other mutations occur, e.g: commonly in the Kras gene
  3. Mutations occur in p53 and other important genes; also, there can be chromosomal deletions
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5
Q

Which chromosomal deletion is assoc. with invasive cancer?

A

18q loss

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6
Q

4 gene types assoc. with cancer and their role?

A

Oncogenes - promote cell growth and division but, when mutated, cause excess growth and division

Tumour suppressor genes - suppress growth and division but, when mutated, allow cell growth and division

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7
Q

Macroscopic appearance of colorectal cancer?

A

Polypoidal - tumor arranged as finger-like processes or as a solid spherical nodule projecting from an epithelial surface

Ulcerative -

Annular - grow centripetally (ring-like) forming what radiologists call an apple core lesion, that constricts the colon

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8
Q

In which regions does colorectal carcinoma tend to occur?

A

Rectum, distal sigmoid colon and then caecum

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9
Q

3 types of adenocarcinoma, in relation to differentiation, and that these phrases mean?

A

Well differentiated - there are still normal features of the tissue, e.g: mucin producing

Moderately differentiated

Poorly differentiated - can no longer determine original tissue

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10
Q

Two staging methods of colorectal cancer?

A

Dukes’ - A, B, C and D

TNM (Tumour, Node, Metastases)

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11
Q

What do Dukes A, B, C and D mean?

A

A - limited to muscularis mucosae

B - extension through muscularis mucosae

C - involvement of regional lymph nodes

D - distant metastases

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12
Q

Explain the TNM staging?

A

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

N0 - no lymph node involvement
N1 - 3 nodes involved

M0 - no distant metastases
M1 – distant metastases

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13
Q

What does local spread mean?

A

To adjacent structures

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14
Q

What does lymphatic spread of colorectal cancer mean?

A

To pericolic nodes and/or perivascular nodes

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15
Q

What does blood spread of colorectal cancer mean?

A

Usually, to liver and lungs

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16
Q

What does transcoelomic spread of colorectal cancer mean?

A

Peritoneal cavity

17
Q

3 factors contributing to colorectal cancer development?

A

Environment, genetic factors and predisposing conditions

18
Q

Protective factors against development of colorectal cancer?

A

Vegetable, fibre and EXERCISE

19
Q

Causative factors against development of colorectal cancer?

A

Red and processed meat, smoking, alcohol and OBESITY

20
Q

Describe the role of AMP kinase (AMPK) in colorectal cancer development

A

LKB1 (a tumour suppressor) activates AMPK, which increases glucose uptake my muscle cells and decreases cell turnover

21
Q

How does exercise affect AMPK?

A

Exercise increases the activity of AMPK and so there is less cell turnover (and increased glucose uptake by muscle cells)

22
Q

Two types of autosomal dominant inheritance of colorectal cancer?

A

FAP (Familial Adenomatous Polyposis)

HNPCC (Hereditary Non-Polyposis Colorectal carcinoma)

23
Q

Describe FAP

A

Germ-line mutation in APC gene that dramatically increases colorectal cancer risk

24
Q

Describe HNPCC

A

Mutation in DNA mis-match repair gene that also increases risk of colorectal cancer

25
Q

Differences between FAP and HNPCC?

A

FAP - many polyps forms (100s)

HNPCC - do not form as many polyps

26
Q

Diseases that predispose to colorectal cancer?

A

Adenomatous polyps

UC

Crohn’s disease

27
Q

Main symptoms of rectal carcinoma?

A

Rectal bleeding

Tenesmus

28
Q

Main symptoms of left-sided colorectal carcinoma?

A

Pain
Change in bowel habit
Rectal bleeding

29
Q

Main symptoms of right-sided colorectal cancer?

A

Anaemia (bleeding small amounts for a long time)

30
Q

Clinical findings in colorectal carcinoma?

A

General - anaemia, cachexia, lymphadenopathy

Abdomen - mass, hepatomegaly, distension (ascites or obstruction)

Rectum - mass and blood

31
Q

Main Ix for diagnosis of primary colorectal carcinoma?

A

Barium enema

CT colography

Sigmoidoscopy

Colonoscopy (gold standard)

32
Q

Screening tests for blood in stool?

A

Faecal Occult Blood Testing (FOBT)

Immunochemical testing (antibodies to human Hb)

33
Q

Describe FOBT

A

Detection of cancer depends on sensitivity; it may be useful in symptomatic patients, at high-sensitivity, as a rule-out method

For screening programmes, it is used at a lower sensitivity (otherwise, too many false positives are detected)

34
Q

Investigations required to stage colorectal carcinoma?

A

Lungs and liver require a CT scan; for primary rectal cancer, an MRI is used

35
Q

How does colorectal cancer present as an emergency?

A

With OBSTRUCTION, i.e: there will be distension, constipation, pain and vomiting

Bleeding

Perforation

36
Q

4 treatment options for obstructive colorectal carcinoma?

A

Colostomy alone

Resection + colostomy

Resection + anastamoses

Stenting

37
Q

Elective treatment options for colorectal cancer?

A

Surgery (usually, the only curative option) - draining lymph nodes must also be removed

Radiotherapy - can be adjuvant (pre or post-operative) and reduces local recurrence after rectal excision; or can be palliative

Chemotherapy - can be used as an adjuvant, in addition to surgery, or for advanced disease (e.g: oxaliplatic, irinorecan, cetuximab, bevacizumab)

38
Q

Surgery types for rectal cancer?

A

APER - excision of rectum through the abdomen and perineum

Anterior resection - for low sigmoid/high rectal tumours

39
Q

Surgery types for colonic cancer?

A

Right hemicolectomy

Extended right hemicolectomy

Transverse colectomy

Left hemicolectomy

Sigmoid colectomy

Subtotal colectomy