Colorectal Cancer Flashcards

1
Q

What cause of cancer death is colorectal cancer?

A

2nd leading

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2
Q

What overall cause of cancer is colorectal cancer?

A

3rd

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3
Q

What is the most common histological classification of colorectal cancer?

A

Adenocarcinoma (95%)

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4
Q

What percentage of colorectal cancer is colonic and what is rectal?

A

2/3 is colonic

1/3 is rectal

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5
Q

What genes are associated with colorectal cancer?

A

HNPCC (5%)

FAP (<1%)

Other CRP syndromes

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6
Q

What are risk factors for sporadic cases of colorectal cancer?

A

Age

Male gender

Previous adenoma

Environmental influences (diet, obesity, lack of exercise, smoking, diabetes)

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7
Q

What kind of things in your diet are risk factors for colorectal cancer?

A

Low fibre

Low fruit and veg

Low calcium

High red meat

High alcohol

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8
Q

What percentage of colorectal cancers have no genetic influence?

A

85%

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9
Q

What do majority of colorectal cancers arise from?

A

Pre-existing polyps

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10
Q

What are polyps?

A

Protuberant growths

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11
Q

What are the different kinds of polyps?

A

Epithelial or mesenchymal

Benign or malignant

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12
Q

What is an adenoma?

A

Benign tumour of glandular tissue

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13
Q

What is an adenoma in origin?

A

Epithelial

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14
Q

What are the different histological types of adenoma?

A

Tubular (75%)

Indeterminate tubulovillous (15%)

Villous (10%)

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15
Q

Explain the adenoma-carcinoma sequence?

A

Activation of oncogene, loss of tumour suppresor gene and defective DNA repair pathway genes (microsatelite instability) cause adenoma to become carcinoma by causing cell growth proliferation apoptosis

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16
Q

What are examples of oncogenes?

A

K-ras

C-myc

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17
Q

What is an oncogene?

A

A gene that has the potential to cause cancer

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18
Q

What are examples of tumour suppressor genes?

A

APC

p53

DCC

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19
Q

What are tumour suppresor genes?

A

Ones that control cell growth

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20
Q

What is the presentation of colorectal cancer?

A

Rectal bleeding (especially if mixed in with stool)

Altered bowel opening to loose stools (longer than 4 weeks)

Palpable rectal or right lower abdominal mass

Acute chronic obstruction if stenosing tumour

Weight loss

Anorexia

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21
Q

What investigations are done for colorectal cancer?

A

Colonoscopy

Radiological imaging

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22
Q

What is the investigation of choice for colorectal cancer?

A

Colonoscopy

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23
Q

What can be done with a colonoscopy?

A

Tissue biopsy

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24
Q

What does a colonoscopy require?

A

Sedation

Bowel preparation

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25
Q

What are risks of a colonoscopy?

A

Perforation

Bleeding

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26
Q

What radiological imaging is done for colorectal cancer?

A

CT colonography

Barium enema

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27
Q

What investigations are done to stage colorectal cancer?

A

CT scan of chest/abdomen/pelvis

MRI scan for rectal tumours

PET scan/rectal endoscopic ultrasound in selected cases

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28
Q

For Duke’s staging, what is T1 to T4?

A

T1 - confined to submucosa

T2 - confined to muscularis

T3 - confined to serosa

T4 - breached serosa, invading other structures

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29
Q

For Duke’s staging, what is N0 to N2?

A

N0 - no lymph node involvement

N1 - seen in 3 regional lymph nodes

N2 - seen in 4+ regional lymph nodes

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30
Q

For Duke’s staging, what is M0 to M1?

A

M0 - no metastases to distinct organs

M1 - metastasis to distinct organs

31
Q

What is the treatment for colorectal cancer?

A

Surgery

Chemotherapy

Radiotherapy

32
Q

What are the 2 surgical options for colorectal cancer?

A

Laparotomy vs laparosopic

33
Q

When is radiotherapy used?

A

Only for rectal cancer

34
Q

What is used for palliative care of advanced disease?

A

Chemotherapy

Colonic stenting to prevent colonic obstruction

35
Q

What does the prognosis of colorectal cancer depend on?

A

What stage it is

36
Q

What is 5 year survival of Duke’s stage A?

A

83%

37
Q

What is 5 year survival of Duke’s stage B?

A

64%

38
Q

What is 5 year survival for Duke’s stage C?

A

38%

39
Q

What is 5 year survival of Duke’s stage D?

A

3%

40
Q

What can prognosis of colorectal cancer be improved by?

A

Prevention (changing lifestyle factors)

Screening (high risk groups and average risk population)

41
Q

What is the aim of population screening?

A

Detect pre-malignant adenomas/early cancers in the general population

42
Q

What are some modalities of screening?

A

Faecal occult blood test (FOBT)

Faecal immunochemical (FIT)

Flexible sigmoidoscopy

Colonoscopy

CT colonography

43
Q

When does the Scottish population start getting an FOBT every 2 years?

A

Between age 50 to 74

44
Q

What happens if a FOBT is positive?

A

Colonoscopy

45
Q

What does FOBT stand for?

A

Faecal occult blood test

46
Q

Does FOBT have a greater positivity in men or woman?

A

Men

47
Q

What does faecal immunochemical testing check?

A

Specific for human haemoglobin

48
Q

What are examples of high risk groups for colorectal cancer that require screening?

A

Heritable conditions (FAP and HNPCC)

Inflammatory bowel disease

Familial risk

Previous adenomas/colorectal cancer

49
Q

What does FAP stand for?

A

Familial adenomatous polyposis

50
Q

What does HNPCC stand for?

A

Hereditary non-polyposis colorectal cancer

51
Q

What kind of genetic condition if FAP?

A

Autosomal dominant

52
Q

What gene is FAP a mutation of?

A

ACP gene on chromosome 5

53
Q

What do people with FAP have a high risk of?

A

Malignant change in early adulthood, in almost all cases by age 40 years if left untreated

54
Q

What screening is done for people with FAP?

A

Annual colonoscopy from age 10-12

55
Q

Other than screening, what else is often done for people with FAP to reduce the risk of colorectal cancer?

A

Prophylactic proctocolectomy usually age 16 to 25

56
Q

What is proctocolectomy?

A

Surgical removal of all of the rectum and part of the colon

57
Q

What are extracolonic manifestations of FAP?

A

Benign gastric fundic cystic hyperplastic

Duodenal adenomas with periampullary cancer

58
Q

What kind of chemoprevention is often given to people with FAP?

A

NSAIDs chemoprevention

59
Q

What does NSAIDs chemoprevention do?

A

Reduces the number of polyps and prevent recurrence of higher grade adenomas in the retained rectal segment

60
Q

What kind of genetic condition is HNPCC?

A

Autosomal dominant condition

61
Q

What gene causes HNPCC?

A

Mutation in DNA mismatch repair (MMR) genes

62
Q

What are examples of DNA mismatch repair genes (MMR) that cause HNPCC?

A

MLH1

MSH2

63
Q

What characteristics do tumours caused by HNPCC usually have?

A

Microsatellite instability (MSI) which are frequent mutations in short repeated DNA sequences (microsatellites)

64
Q

Where in the colon does HNPCC usually cause cancer?

A

Right sided

65
Q

Other than the colon, what other sites can HNPCC cause cancer?

A

Endometrial

Genitourinary

Stomach

Pancreas

66
Q

How is HNPCC diagnosed?

A

Clinical criteria (Amsterdam/Bethesda)

Genetic testing

67
Q

What is done for people with HNPCC to reduce the change of them developing colorectal cancer?

A

Screening is given every 2 years as a colonoscopy

68
Q

In terms of a family history of colorectal cancer, who is considered a high moderate risk?

A

Colorectal cancer in 3 first degree relatives where none <50

or

Colorectal cancer in 2 first degree relatives mean age <60

69
Q

What is done for people who are considered a high moderate risk with a family history of colorectal cancer?

A

5 yearly colonoscopy from age 50 years

70
Q

In terms of a family history of colorectal cancer, who is considered to be low moderate risk?

A

Colorectal cancer in 2 first degree relatives >60

or

Colorectal cancer in 1 first degree relative <50 years

71
Q

What is done for people with a family history of colorectal cancer who are considered low moderate risk?

A

Once only colonoscopy at 55 years

72
Q

What are people with IBD given to reduce change of getting colorectal cancer?

A

Index surveillance colonoscopy 10 years post diagnosis, then dependent on duration, extent and activity of inflammation and presence of dysplasia

73
Q

What are people with previous colorectal cancer given to reduce the chance of getting it again?

A

5 yearly colonoscopy

74
Q

What are people with previous adenomas given to reduce the chances of developing colorectal cancer?

A

Colonoscopy dependent on number of polyps, size and degree of dysplasia