[2] Colorectal Cancer Flashcards Preview

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Flashcards in [2] Colorectal Cancer Deck (108)
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1
Q

How does the incidence of colorectal cancer differ from other cancers?

A

It is the third most common cancer in the UK

2
Q

How does the mortality of colorectal cancer differ from other cancers?

A

It has the second highest mortality figures of any cancer

3
Q

What is the occurrence of colorectal cancer strongly associated with?

A

Age

4
Q

What % of presentations of colorectal cancers are in patients in those >60 years?

A

85%

5
Q

Can colorectal cancers occur in patients 20-30 years of age?

A

Yes, particularly in inherited cancer syndromes

6
Q

Where do colorectal cancers originate from?

A

The epithelial cells lining the colon or rectum

7
Q

What is the most common type of colorectal carcinoma?

A

Adenocarcinomas

8
Q

What are the rarer types of colorectal carcinoma?

A

Lymphoma
Carcinoid
Sarcoma

9
Q

How do most colorectal cancers develop?

A

Via a progression of normal mucosa to colonic adenoma (colorectal polyps), to invasive adenocarcinoma

10
Q

How long can adenomas be present before becoming malignant?

A

10 years or more

11
Q

What % of adenomas progress to adenocarcinomas?

A

10%

12
Q

What genetic mutations have been implicated in predisposing individuals to colorectal cancer?

A

Adenomatous polyposis coli (APC) gene

Hereditary non-polyposis colorectal cancer (HNPCC)

13
Q

What is the APC gene?

A

A tumour suppressor gene

14
Q

What does early APC gene mutation and inactivation result in?

A

Growth of adenomatous tissue

15
Q

What condition is APC mutation responsible for the development of?

A

Familial adenomatous polyposis (FAP)

16
Q

What happens in HNPCC?

A

Mutation to DNA mismatch repair genes lead to defects in DNA repair

17
Q

What does HNPCC commonly account for?

A

The familial risk associated with colorectal cancer

18
Q

What % of colorectal cancers are sporadic?

A

Approximately 75%

19
Q

What is meant by sporadic in colorectal cancer?

A

Developing in people with no specific risk factors

20
Q

What are the risk factors for colorectal cancer?

A
Age >60 years
Family history
Inflammatory bowel disease
Low fibre diet
High processed meat intake
High alcohol intake
Smoking
21
Q

What are the common clinical features of bowel cancer?

5

A
Change in bowel habit
Rectal bleeding
Weight loss
Abdominal pain 
Iron-deficiency anaemia
22
Q

When is progressive weight loss present in colorectal cancer?

A

Only with associated metastasis, or rarely sub-acute bowel osbtruction

23
Q

What symptoms may be present with a right-sided colon cancer?

A

Abdominal pain
Occult bleeding
Mass in right iliac fossa

24
Q

What symptoms may be present with a left-sided colon cancer?

A

Rectal bleeding
Change in bowel habit or tenesmus
Mass in left iliac fossa/mass on PR exam

25
Q

When should patients be referred for urgent investigations for suspected bowel cancer?

A

40 or older with unexplained weight loss and abdominal pain
50 or older with unexplained rectal bleeding
60 or older with iron-deficiency anaemia or changes in bowel habit
Positive occult faecal blood test

26
Q

What are the differential diagnoses for colorectal cancer?

A

Inflammatory bowel disease
Haemorrhoids
Diverticulitis

27
Q

How can inflammatory bowel disease be differentiated from colorectal cancer?

A

The average age of onset is younger (20-40years)

Typically presents with diarrhoea containing blood and mucus

28
Q

How is haemorrhoids differentiated from colorectal cancer?

A

Bright red rectal bleeding covering the surface of the stool

Rarely presents with abdominal discomfort or pain, altered bowel habits, or weight loss

29
Q

How can diverticulitis be differentiated from colorectal cancer?

A

It is likely to cause systemic features of inflammation

30
Q

What is the UK screening programme for colorectal cancer?

A

In the UK, screening is offered every 2 years to men and women aged 60-75 years using faecal occult blood home testing kits

31
Q

How many samples are required for analysis with faecal occult blood home testing kits?

A

3 separate stool samples

32
Q

What happens if any of the stool samples in screening are positive?

A

The patient is offered an appointment with a specialist nurse, and further investigation is conducted with colonoscopy

33
Q

How effective is the colorectal cancer screening programme at detecting cancer?

A

Since its induction, it has increased the detection of colorectal cancer in people aged 60-69 by 11%

34
Q

What investigations might be done in suspected colorectal cancer?

A

Routine bloods
Coloscopy with biopsy
Other imaging

35
Q

What blood tests should be performed for suspected colorectal cancer?

A

FBC
U&Es
LFTs
Coagulation screens

36
Q

What might FBC show in colorectal cancer?

A

May be microcytic anaemia, especially if cancer is on right side of colon

37
Q

What is the use of CEA in colorectal cancer?

A

It should not be used as a diagnostic test, but can be used to monitor disease progression

38
Q

When should CEA be performed in other to screen for recurrence?

A

Pre- and post-treatment

39
Q

Why should CEA not be used for diagnosis of colorectal cancer?

A

Due to poor sensitivity and specificity

40
Q

What is the gold standard for diagnosis of colorectal cancer?

A

Colonoscopy with biopsy

41
Q

What can be used if coloscopy is not suitable for the patient?

A

CT colography or flexible sigmoidoscopy

42
Q

Why may a patient not be suitable for colonoscopy?

A

Frailty
Co-morbidities
Intolerance

43
Q

What is the disadvantage of CT colography or flexible sigmoidoscopy compared to colonoscopy?

A

It is not as sensitive or specific as colonoscopy

44
Q

What other imaging investigations are required once the diagnosis is made?

A

CT chest/abdo/pelvis
MRI rectum
Endo-anal ultrasound

45
Q

What is the purpose of the CT chest/abdo/pelvis in colorectal cancer?

A

Look for distant metastasis and local invasion

46
Q

How can full colonoscopy or CT colonogram be used in confirmed diagnoses of colorectal cancer?

A

To check for a 2nd tumour, if not used initially

47
Q

When is a MRI rectum required in confirmed cases of colorectal cancer?

A

Rectal cancers only

48
Q

What is the purpose of MRI rectum in colorectal cancers?

A

To assess the depth of invasion, and hence the need for pre-operative chemotherapy

49
Q

When is an endo-anal ultrasound required in confirmed colorectal cancer?

A

Early-rectal cancers (T1 or T2) only

50
Q

What is the purpose of an endo-anal ultrasound in early rectal cancers?

A

To assess suitability for trans-anal resection

51
Q

How can colorectal cancers be staged?

A

TNM

Dukes staging

52
Q

What does TNM staging stage cancers depending on in colorectal cancer?

A

The depth the tumour invades the bowel wall
The extent of spread to local lymph nodes
If distant mets are present

53
Q

Is the Duke’s staging system used?

A

It has been largely superseded, but is still used at some centres for additional staging detail

54
Q

What constitutes a Dukes A?

A

Confined beneath the muscularis mucosa

55
Q

What is the 5 year survival of Dukes A cancer?

A

90%

56
Q

What constitutes a Dukes B?

A

Extension through the muscularis mucosa

57
Q

What is the 5 year survival of Dukes B cancer?

A

65%

58
Q

What constitutes a Dukes C?

A

Involvement of regional lymph nodes

59
Q

What is the 5 year survival of Dukes C cancer?

A

30%

60
Q

What constitutes a Dukes D?

A

Distant metastasis

61
Q

What is the 5 year survival of a Dukes D cancer?

A

<10%

62
Q

What are the treatment options for colorectal cancer?

A

The only definitive curative treatment is surgery, yet chemotherapy and radiotherapy have an important role as neoadjuvant/adjuvant treatment, as well as pallitation

63
Q

Where is surgery the mainstay of curative management of colorectal cancer?

A

For localised malignancy in the bowel

64
Q

What is the general plan in most surgical management for colorectal cancer?

A

Suitable regional colectomy followed by primary anastomosis or formation of a stoma

65
Q

What is the purpose of a regional colectomy in colorectal cancer?

A

To ensure removal of the primary tumour with adequate margins and lymphatic drainage,

66
Q

What is the purpose of primary anastomosis or formation of a stoma in colorectal cancer?

A

To restore bowel function

67
Q

What are the types of regional colectomy?

A
Right hemicolectomy and extended right hemicolectomy
Left hemicolectomy
Sigmoidcolectomy
Anterior resection
Abdominoperineal resection
68
Q

Where is a right hemicolectomy used?

A

For caecal or ascending colon tumours

69
Q

What happens to the vessels during a right hemicolectomy?

A

The ileocolic, right colic, and right branch of the middle colic vessels are divided and removed with their mesenteries

70
Q

What is an extended right hemicolectomy typically performed for?

A

Any transverse colon cancers

71
Q

Where is a left hemicolectomy used?

A

For descending colon cancers

72
Q

What happens to the vessels during a left hemicolectomy?

A

The left branch of the middle colic vessels, the inferior mesenteric vein, and the left colic vessels are divided and removed with their mesenteries

73
Q

Where is a sigmoidcolectomy used?

A

For sigmoid colon tumours

74
Q

What happens to the vessels during a sigmoidcolectoym?

A

The IMA is fully dissected out with the tumour to ensure adequate margins are obtained

75
Q

Where is an anterior resection used?

A

For high rectal tumours, typically if >5cm from anus

76
Q

Why is an anterior resection approach favouring in rectal carcinoma?

A

As resection leaves the rectal sphincter in tact and functioning if anastomosis is performed, unlike AP resections

77
Q

What is often performed with anterior resections?

A

A defunctioning loop ileostomy

78
Q

Why is a defunctioning loop ileostomy often performed with anterior resections?

A

To protect the anastomosis, and reduce complications in the event of an anastomotic leak

79
Q

What happens to a defuntioning loop ileostomy long term?

A

It is reversed electively approx. 4-6 months later

80
Q

Where is an abdominoperineal resection performed?

A

Low rectal tumours, typically <5cm from anus

81
Q

What does an abdominoperineal resection involve?

A

Excision of the distal colon, rectum, and anal sphincters

82
Q

What does an abdominoperineal resection result in long-term?

A

A pernament colostomy

83
Q

Why are bowel resections often performed laparoscopically?

A

As this offers faster recovery times, reduced surgical site infection risk, and reduced post-operative pain, with no difference in disease recurrence or overall survival rates when compared to open surgery

84
Q

Where is a Hartmann’s procedure used?

A

In emergency bowel surgery, such as bowel obstruction or perforation

85
Q

What does a Hartmann’s procedure involve?

A

A complete resection of the recto-sigmoid colon with the formation of an end-colostomy and the closure of the rectal stump

86
Q

Where is chemotherapy typically indicated in colorectal carcinoma?

A

In patients with metastatic disease

87
Q

How the decision on what chemotherapy agents to use made in colorectal cancer?

A

Will be decided by MDT

88
Q

Give an example of a chemotherapy regime used for patients with metastatic colorectal cancer?

A

FOLFOX - folinic acid, fluorouracil, and oxaliplatin

89
Q

What kind of colorectal cancer can radiotherapy be used in?

A

Rectal cancer

90
Q

What is the role of radiotherapy in rectal cancer?

A

Most often as a neo-adjuvant treatment

91
Q

Why is radiotherapy rarely given in colon cancer?

A

Due to the risk of damage to the small bowel

92
Q

Where is radiotherapy of particular use?

A

In patients with rectal cancers which look in MRI to have a ‘threatened’ circumferential resection (i.e. within 1mm)

93
Q

What can be done in patients with rectal cancers with a ‘threatened’ circumferential resection?

A

They can undergo a pre-operative long-course chemo-radiotherapy to shrink the tumour, thereby increasing the chance of complete resection and cure

94
Q

How will many high staging colorectal cancers be managed?

A

Palliatively

95
Q

What is the purpose of the palliative management of colorectal cancer?

A

Reducing cancer growth and ensuring adequate symptom control

96
Q

What are the important surgical options for palliative care available?

A

Endoluminal stenting
Stoma formation
Resection of secondaries

97
Q

What is the purpose of endoluminal stenting in colorectal cancer?

A

It can be used to relieve acute large bowel obstruction in patients with left sided tumours

98
Q

Why can endoluminal stenting not be used in low rectal tumours?

A

Due to the unpleasant side-effects of intractable tenesmus

99
Q

What are the main side-effects of endo-luminal stenting?

A

Perforation
Migration
Incontinence

100
Q

What is the purpose of stoma formation in colorectal cancer?

A

Relieve acute obstruction

101
Q

How is stoma formation usually performed to relieve acute obstruction in colorectal cancer?

A

Either a defunctioning stoma or pallative bypass

102
Q

When can resection of metastases be done?

A

With adjuvant chemotherapy for any liver mets

103
Q

When should patients receiving curative treatment for colorectal cancer first be followed up?

A

4-6 weeks after finishing treatment

104
Q

How many CT CAP’s should a patient receive in the first 3 years after curative treatment for colorectal cancer?

A

At least 2

105
Q

What should patient be offered 1 year after surgery for colorectal cancer?

A

Colonoscopy

106
Q

If the colonoscopy is normal after surgery for colorectal cancer, when should the patient have another?

A

5 years

107
Q

When should follow-up following treatment for colorectal cancer be stepped down?

A

When patient and clinician agree risk of further testing outweighs the benefits

108
Q

What should patients who have suspected return of colorectal cancer be offered?

A

Same level of testing as they had the first time