Bowel Cancer

Question 1

Ten year survival rate for bowel cancer

Answer 1

53%

Question 2

Polyp

Answer 2

is a projecting growth of tissue from a surface in the body usually a mucous membrane and can develop in the colon, rectum, ear canal, cervix, stomach, nose, uteruses, throat and bladder

Question 3

Adenomatous polyps in the large bowel are cancerous.

True or False?

Answer 3

False
precancerous but only 5% progress into cancer can be 10 years

Question 4

Colorectal cancer begins with the formation of a

Answer 4

small fixed adenoma

Question 5

Pathogenesis of Bowel Cancer:

Answer 5

• small adenomas could progress into more advances,
  more giant fixed adenomas
• all adenomatous polyps have dysplasia, size is not
  relevant, though larger polyps may be more likely to
  have high grade dysplasia
• some cancers will be seen in very small polyps and
  many large polyps do not have cancer or even high
  grade dysplasia

Question 6

Adenoma-carcinoma sequence

Answer 6

• low grade dysplasia to high grade dysplasia, CRC

***APC inactivation

Question 7

adenoma carcinoma sequence

Answer 7

Question 8

Screening and prevention of bowel cancer (wilson’s criteria):

Answer 8

• identification of a pre-malignant phase (polyp)
• there is a good and acceptable test (colonoscopy)
• there is an agreed and acceptable treatment
  (polypectomy)

Question 9

serrated pathway in colorectal cancer

Answer 9

Question 10

Genetics of colo-rectal cancer:

Answer 10

• 75% are sporadic
• 20% of CRC patients report a family history of the
  disease
• 3-5% are hereditary due to the highly penetrant
  germline mutations

Question 11

Two forms of hereditary colorectal cancer:

Answer 11

• polyposis
• lynch syndrome

Question 12

Polyposis:

Answer 12

• familial adenomatous polyposis (FAP)are caused by
  pathogenic varients in APC gene which is
  chromosome 5q21
• MUTHY-associated polyposis: caused by pathogenic
  variants in the MUYTH gene

Question 13

What does the APC gene do?

Answer 13

• APC gene provides instructions for making the APC
  protein, which is critical in several cellular processes
• the apc protein acts as a tumour suppressor and
  keeps cells from growing and dividing too fast or
  uncontrolled

Question 14

Lynch syndrome (hereditary nonpolyposis colorectal cancer):

Answer 14

• caused by germline pathogenic varients in DNA
  mismatch repair genes (MMR genes and EPCAM)

Question 15

Two Hit Hypothesis

Answer 15

• two genetic abnormalities are required (both copies
  of the affected gene) to develop certain cancers
• those with a hereditary susceptibility to cancer inherit
  a damage chromosme , hence their first hit occurs at
  conception, whereas others may receive their first hit
  at a later stage

Question 16

Two hit theory of cancer causation

Answer 16

Question 17

Familial Adenomatous Polyposis (FAP):

Answer 17

• autosomal dominant
• 25% are new mutations; no family history
• > 100 polyps by late teens
• almost 100% risk of bowel cancer by 30
• surgery is reccomended by the 20s
• screening for cancers/polyps in stomach, small bowel
  and thyroid

Question 18

Lynch syndrome (hereditary nonpolyposis colorectal cancer):
-what % of cases are new mutations?
- does or doesnt follow two hit hypothesis?
- increases risk of what type of cancers?

Answer 18

• 20% are new mutations
• follows two hit hypothesis
• increases risk of endometrial and renal cell cancer,
  sometimes breast, upper GI and prostate

Question 19

Bowel Cancer Staging:

Answer 19

• TNM
• tumour: has the tumour grown into the wall of colon
  or rectum? How many layers (serosa etc)?
• nodes: has the tumour spread to the lymph nodes?
  where and how many?
• metastasis: has the cancer spread to other parts of
  the body? Where and how much?

Question 20

Distant metastasis sites of colorectal cancer?

Answer 20

• brain
• lungs
• liver (most)
• spleen
• mesentery (omentum)
• bone

Question 21

Bowel Cancer: Risk factors:

Answer 21

• higher incidence in western world, and white
• roughly equal in both men and women
• 2/3 occur in those over 60
• genetics: polyposis like FAP
• longstanding inflammatory bowel disease like UC

Question 22

What % of bowel cancer is preventable in the UK?

Answer 22

54%
(meat, alcohol, smoking)

Question 23

High dietary fibre reduces the risk of bowel cancer:

Answer 23

• increases the formation of short chain fatty acids
• reduce stool transit time
• reduces secondary bile acid formation

Question 24

High dietary fibre reduces the risk of bowel cancer: increases the formation of short chain fatty acids:

Answer 24

• promotes healthy gut bacteria, which can induce cell
  differentiation, arrest cell growth and cause apoptosis
• reduce proliferation of neoplastic cells

Question 25

High dietary fibre reduces the risk of bowel cancer: reduce stool transit time:

Answer 25

• carcinogens are common in food, faster transit means
  less time for these to act on the bowel mucosa

Question 26

High dietary fibre reduces the risk of bowel cancer: reduces secondary bile acid formation:

Answer 26

• potentially carcinogenic

Question 27

Clinical features of bowel cancer:

Answer 27

• changes in bowel movements
• gas/bloating
• abdo discomfort
• nausea/vomiting
• fatigue
• weight loss
• loss of appetite
• anaemia
• cramping

Question 28

Clinical features of Rectal cancer:

Answer 28

• rectal bleeding
• change in bowel habits
• rectal pressure or fullness
• thin or ribbon like stools
• anaemia
• cramping
• weight loss
• loss of appetite
• fatigue

Question 29

Clinical presentation of bowel cancer:

Answer 29

• > 60:
  • iron deficiency anaemia
  • change in bowel habit
• > 50:
  • unexplained rectal bleeding
• <50:
  
  • unexplained rectal bleeding
  • abdominal pain
  • change in bowel habits
  • weight loss
  • iron deficiency anaemia
• > 40:
  • weight loss and abdo pain
• any age with abdo or rectal mass

Question 30

Bowel Cancer Screening:

Answer 30

• 60-74
• every two years
• qFIT
• detects human goblin (amount of blood in stool)
• > 75 can request one every two years

Question 31

Limitations of qFIT:

Answer 31

• 50% patients with documented colorectal cancers
  have a negative faecal occult blood test, consistent
  with the intermittent bleeding pattern of these
  tumours

Question 32

If qFIT is positive then definitely cancer/

True or False?

Answer 32

False
follow up tests required to determine the reason for the presence of blood in the stool

Question 33

Further investigations for bowel cancer:

Answer 33

• qFIT
• physical exam
• colonoscopy “goldstandard”
• biopsy
• biomarker testing to identify specific genes, unique
  factors of tumour
• blood tests: anaemia (due to bleeding)
• ultrasound, CXR, CT, MRI