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Yr2 GI Joe > Colorectal cancer and screening > Flashcards

Colorectal cancer and screening Flashcards

1
Q

How many people die from colorectal cancer per year in the UK

A

17,000 per year

(second biggest cancer killer in western world)

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2
Q

What histological type of cancer does colorectal cancer tend to be?

A

Adenocarcinoma (95%)

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3
Q

Describe the role of genetics as a risk factor for colorectal cancer

A

85% of CRC is sporadic and has no link to genetics

10% of patients have a ‘familial risk’

Inheritible predisposing conditions such as mutated HNPCC, FAP account for 5%

1% caused by IBD

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4
Q

What are the risk factors for CRC?

A

Old age

Male

Previous adenoma/CRC

Previous IBD

Poor diet / obesity / Lack of exercise

Smoking

Diabetes

Family history

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5
Q

Most colorectal cancers begin as _______

A

Polyps (adenomas)

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6
Q

What are the main histological types of polyp (adenoma)?

A

Tubular (75%)

Indeterminate tubulovillous (15%)

Villous (10%)

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7
Q

What is the difference between a pedunculated and sessile polyp?

A

Pedunculated - polyp has a connective tissue stalk

Sessile - no stalk

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8
Q

What dietary factors can increase the risk of CRC?

A

Low Fibre, fruit & veg and calcium

High red meat and alcohol

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9
Q

What changes occur that allow adenomas to become carcinomas (cancerous)?

A

Activation of oncogene

Loss of tumour suppressor gene

Defective DNA pathway repair genes - microsatellite instability

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10
Q

Give examples of oncogenes that can be activated to allow CRC to develop

A

k-ras

c-myc

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11
Q

Give examples of tumour suppressor genes

A

APC

p53

DCC

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12
Q

What are the main symptoms of Colorectal cancer?

A

Rectal bleeding

Change in bowel habit - looser and more frequent stools

<em>For above^: if 1 then investigate > 60s, if both then investigate > 40</em> <em>year olds</em>

Tenesmus - urge to defecate / rectal fullness

Symptoms of anaemia (iron deficiency): lethargy, breathlessness etc

Weight loss

Systemic symptoms: Weight loss, anorexia

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13
Q

Cancers in the caecum and right colon are often asymptomatic until they present as _________

A

Often asymptomatic until they present as iron deficiency anaemia

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14
Q

What are the main signs of Colorectal cancer?

A

Rectal or abdominal mass may be palpable

Iron deficiency anaemia

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15
Q

How can colorectal cancer present as an emergency?

A

Can cause acute colonic obstruction if the tumour is stenosing

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16
Q

What is the primary investigation for CRC?

A

Colonoscopy - gold standard

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17
Q

What are the benefits and problems with colonoscopies?

A

Pros:

  • Good view
  • Biopsies (mandatory)
  • Can be used therapeutically (polypectomy)

Cons:

  • Requires sedation
  • Risk of perforation, bleeding etc
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18
Q

What radiological imaging can be used to investigate CRC?

A

CT colonography - gives 3D virtual colonoscopy (good for visuals)

Barium enema

CT abdo/pelvis

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19
Q

What investigations are done to stage CRC?

A

CT scan: Chest, abdo, pelvis

MRI scan for Rectal tumours

PET scan / rectal endoscopic ultrasound (in some cases) - i think these are done if to look at anything suspicious (metastasis) on the CT/MRI

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20
Q

What staging system is used in CRC?

A

Dukes’ staging system (which uses TNM)

21
Q

What is the treatment approach to CRC?

A

Surgery used in about 80% of cases

Adjuvant postoperative chemotherapy often used (more later)

Radiotherapy is only useful in rectal cancer

Palliative: Chemo and stenting are options

22
Q

What is Dukes A CRC and how is it treated?

A

A = tumour confined to the mucosa

Treated using endoscopic or local resection

(same with polyps)

23
Q

How are more advanced cancers treated?

A

Operative procedure variable - depending on site, stage and size of tumour

Surgery tends to be laparoscopically but can be done as laparotomy

Some patients require colostomy - stoma formation may be temporary/permanent

Palliative: Chemotherapy, colonic stenting

24
Q

When is chemotherapy indicated for use?

A

Dukes C / sometimes Dukes B

Used adjuvantly (postoperative)

Used if there is positive lymph node histology as it is useful fo ‘mopping up’ micrometastasis

25
Q

What main chemo agent are used for adjuvant treatment of CRC?

A

5-FU (fluorouracil)

+/- others but we dont care about that

26
Q

When is radiotherapy indicated?

A

Rectal cancer only

Is used Neoadjuvantly (before surgery) +/- chemotherapy to control primary tumour prior to surgery

27
Q

Why is stenting used in palliative care for CRC?

A

To prevent colonic obstruction (large bowel obstruction)

To improve patients remaining time as much as possible

28
Q

What is the prognosis for each Dukes stage?

(ignore the photo if the answers are different)

A

A - 83% 5 year survival

B - 64%”

C - 38%”

D - 3%”

29
Q

What lifestyle advice should be given to patients to reduce their chances of developing CRC?

A

30 mins physical activity on most days

BMI 18.5-25.0 kg/m2

5 or more portions fruit and veg

Dont smoke / quit smoking

30
Q

What is the aim of population screening for CRC?

A

Detect pre-malignant / early cancers in the general population

31
Q

What modalities are used for screening for CRC?

A

Faecal occult blood test (FOBT)

Faecal immunochemical test (FIT)

Flexible sigmoidoscopy

Colonoscopy

CT colonography

32
Q

What is the scottish screening programme for CRC in 2007?

A

50-74 year olds

FOBT every 2 years

If FOBT positive then receive colonoscopy

33
Q

What test is currently being used in scotland (as of 2017) to screen for CRC and what are it’s advantages?

A

Faecal immunochemical testing (FIT)

Automated, quantitive and more user friendly than FOBT

34
Q

What high risk groups are screened for CRC?

A

Those with Heritable conditions:

  • FAP (familial adenomatous polyposis)
  • HNPCC (hereditary non-polyposis colorectal cancer)

Inflammatory bowel disease

Familial risk

Previous adenomas / colorectal cancers

35
Q

What is FAP?

A

Familial adenomatous polyposis

Autosomal dominant condition in which the epithelium of the colon becomes covered in adenomas (polyps)

Caused by mutation of APC gene on chromosome 5

36
Q

How are FAP patients managed?

A

Screening - annual colonoscopy from ages 10-12 up

Prophylactic proctocolectomy usually at age 16-25 years old

37
Q

What are the extracolonic manifestations of FAP?

A

Benign gastric fundic cystic hyperplastic (not a clue what this is meaning)

Duodenal adenomas in 90% with periampullary cancer in around 5% (surveillence endoscopy)

Desmoid tumours (10-20%) - noncancerous CT growths

CHRPE - congenital retinal hypertrophy of the pigment epithelia

38
Q

What drugs group can be used to help patients with FAP and how?

A

Some NSAIDs work as chemoprevention

E.g. Sulindac reduces polyp number and prevents recurrence of high grade adenomas in the retained segment after a proctectomy

39
Q

What is HNPCC?

A

Hereditary nonpolyposis colorectal cancer (HNPCC) - most common form of hereditary colorectal cancer

Autosomal dominant syndrome - defective mismatch repair (MMR) proteins:

  • MLH1
  • MSH2

HNPCC, accounts for 2-5% of all colorectal carcinomas

40
Q

What is different about HNPCC tumurs compared to other tumours?

A

Typically have molecular characteristic called microsatellite instability

(frequent mutations in short repeated DNA sequences (microsatellites))

41
Q

How would a patient with HNPCC present with cancer?

A

Early onset colorectal cancer which tends to be right sided (Ascending colon)

May have cancer in other sites: endometrial, genitourinary, stomach, pancreas

42
Q

How is HNPCC diagnosed and managed?

A

Diagnosed through genetic testing - clinical criteria (Amsterdam / Bethesda)

Screening from age 25: colonoscopy every 2 years

43
Q

How are patientsd with a familial risk of CRC screened?

A

CRC in 3 FDRs with mean age <60

  • -> High moderate risk
  • -> 5 yrly colonoscopy from age 50

CRC in 2 FDRs over 60 or in 1 FDR <50

  • -> Low Moderate Risk
  • -> One Colonoscopy at age 55
44
Q

How is CRC screened for in patients with IBD?

A

A surveillance colonoscopy 10yrs post diagnosis
Then further investigations dependant on duration, extent, dysplasia and activity of the IBD

45
Q

How often are patients with a history of CRC screened and how?

A

Colonoscopy every 5 years

46
Q

What determines the screening programme for patients with previous adenomas?

A

Dependant on number of polyps, size and degree of dysplasia

47
Q

What new investigations are surfacing for screening/detection of CRC

Why are these good?

A

Faecal haemoglobin testing - could be a good ‘rule out test’ for significant bowel disease and would avoid unnecessary colonoscopy

48
Q

Summarise the primary care investigation for a patient suspicious for CRC

(before imaging n all that shite)

A

Full blood count

U+E’s

FIT test (stool test)

49
Q
A

Yr2 GI Joe (28 decks)

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