Colorectal Cancer Flashcards

1
Q

What are the 3 red flag symptoms for bowel cancer?

A
  1. rectal bleeding
  2. weight loss
  3. family history
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2
Q

What is significant to ask if there is a family history of colorectal cancer?

A

the age of the family members when they were affected

this is more concerning if they were younger

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3
Q

If a GP suspects potential colorectal cancer, who do they refer to?

What does this person do when they meet the patient for the first time?

A

they refer for a secondary care opinion to a colorectal surgeon

the surgeon takes a full clinical history and performs a full clinical examination, including a digital rectal examination

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4
Q

What are the 3 main risk factors for colorectal cancer?

A
  1. increased age
  2. male gender
  3. family history
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5
Q

What are the other 6 risk factors for colorectal cancer?

A
  1. obesity and sedentary lifestyle
  2. smoking and drinking alcohol
  3. eating too much red meat
  4. eating too little fruit/vegetables
  5. idiopathic inflammatory bowel disease
  6. previous polyps/cancers in the bowel
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6
Q

How can the risk of colorectal cancer be reduced?

A
  1. increasing fibre intake
  2. having a healthy diet including fruit and vegetables
  3. aspirin reduces the risk of developing polyps
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7
Q

What are the 2 types of colorectal cancer?

A

sporadic CRC - accounts for 90-95% of cases

hereditary CRC - accounts for 5-10% of cases

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8
Q

What may suggest that someone has sporadic colorectal cancer?

A

there is no evidence of a hereditary syndrome

there may still be a familial component

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9
Q

What are the 2 main hereditary syndromes responsible for causing hereditary colorectal cancer?

A
  1. familial adenomatous polyposis (FAP)
  2. Lynch syndrome
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10
Q

What type of inheritance is seen in FAP?

What gene is affected?

A

autosomal dominant inheritance

the affected gene is the adenomatous polyposis coli (APC) gene

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11
Q

When do tumours tend to develop in FAP?

Are these cancerous?

A

tumours develop very early (2nd decade)

the bowel becomes covered with a minimum of 100 polyps

carcinoma occurs inevitable by 40 years

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12
Q

What is the major preventative treatment in FAP?

A

prophylactic colectomy is performed in late teens/early 20s

this involves removal of the entire large bowel

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13
Q

What is the Vogelstein sequence?

A

the idea that cancer is caused by sequential mutations of specific oncogenes and tumor suppressor genes

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14
Q

How is the mutation in the APC gene in FAP related to the Vogelstein sequence?

A

it is the first mutation in the sequence

having the APC mutation means the patient’s bowel is in a primed state for hyperproliferation

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15
Q

What is significant about the number of polyps in the bowel of someone with FAP?

A

the risk of any one adenoma (polyp) undergoing malignant transformation is 5%

the excessive number of polyps greatly elevates the combined risk

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16
Q

What type of inheritance is seen in Lynch syndrome?

What mutation is involved?

A

autosomal dominant inheritance

it is caused by a mutation in one of the six DNA mismatch repair genes that are part of the microsatellite instability pathway

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17
Q

What is the role of a mismatch repair gene?

A

they code for proteins that repair any damage to the genome

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18
Q

How is Lynch syndrome related to the Vogelstein sequence?

A

IT ISNT

Mutations in DNA mismatch repair genes follow an alternative pathway for CRC development outside of the Vogelstein sequence

this accounts for around 15% of cases

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19
Q

Why is a colonoscopy the “gold standard” test when further investigating a patient?

A

biopsies can be taken during the procedure to make a tissue diagnosis

this cannot be done on imaging

20
Q

What is a CT colonography?

A

a colonoscopy is recreated virtually

this is less invasive than a colonoscopy which is significant if there are comorbidities present

if something is identified on the scan, biopsies then need to be taken

21
Q

If a polyp is identified on a colonoscopy, what is done to it?

A

the polyps are removed by polypectomy

this is because there is a chance that they may develop into a cancer

22
Q

What type of polypectomy is used for a pedunculated polyp?

A

this is a polyp that hangs from the colon wall on a stalk of bowel tissue

it is removed by snare polypectomy

23
Q

What type of polypectomy is used for sessile polyps?

A

these are flat polyps that are directly attached to the bowel wall

they are removed by endoscopic mucosal resection

24
Q

What is the definition of a polyp?

What are the 2 different categories of polyps found in the bowel?

A

a polyp is a tissue mass that protrudes into the bowel lumen

hyperplastic & inflammatory polyps:

  • these do not have a chance of turning into a cancer

adenomatous polyps:

  • there is a 5% chance that these could turn into cancer
25
Q

What is the definition of an adenoma?

How are colonic adenomas classified?

A

a benign neoplasm of glandular epithelium

they are classified by:

architecture:

  • this is whether they are tubular, villous or tubulovillous

degree of dysplasia:

  • this is either low-grade or high-grade
26
Q

Why are polyps clincally significant?

A

they can be precursors to colorectal cancer

27
Q

What 3 factors increase the risk of malignant transformation of a polyp?

A

size:

  • > 1cm means high risk

histological architecture:

  • villous adenomas have a high risk

severity of dysplasia:

  • high-grade dysplasia links with high risk
28
Q

What is the first location that bowel cancer often metastasizes to and why?

A

once cancer cells access the venous system in the bowel, they metastasize to the liver

blood from the bowel is drained to the liver

29
Q

What is the current NHS bowel cancer screening programme in the UK?

A

screening every 2 years for men and women aged 60-74

(this is being lowered to 50)

this is performed by faecal immunochemical test (FIT) to observe hidden blood in the stool

any positive tests are invited for colonoscopy

30
Q

What is the benefit to the NHS bowel cancer screening programme?

A

cancers can be picked up before they are symptomatic

this means they can be treated before there is a risk of the cancer spreading

31
Q

What are the main risks associated with colonoscopy?

A

1 in 1,500 chance of bowel perforation

1 in 10,000 risk of death

32
Q

What are the most common locations for bowel cancers to develop?

A

the sigmoid colon and the rectum

these can be accessed by slightly less invasive procedures

33
Q

What is meant by an adenocarcinoma?

A

a malignant gland-forming tumour of epithelial origin

34
Q

Typically, what actually is the definition of colorectal cancer?

A

cancer affecting the terminal part of the gut

35
Q

What are the treatment options available for colorectal cancer?

A

surgical resection +/- other preoperative therapies

  1. right hemicolectomy
  2. left hemicolectomy
  3. anterior resection
  4. transverse colectomy
36
Q

When may CT scans be used in colorectal cancer patients?

A

CT scans are important in staging

this involves ensuring that the tumour has not spread elsewhere

37
Q

What are the following parts of the large bowel?

A
38
Q

In a hemicolectomy, what other structures are removed?

A

the associated lymph nodes and venous drainage

39
Q

What is meant by “staging” of colorectal cancer?

What are the 2 types of staging and why is it important?

A

it is the determination of the extent of spread of a tumour at presentation

There is TNM and Duke’s staging

It determines treatment and prognosis

40
Q

What is involved in TNM staging?

A

TUMOUR NODES METASTASIS

  • T shows how far through the bowel wall the cancer has spread
  • N shows the number of lymph nodes the cancer has spread to
  • M represents distant metastases
41
Q

How does staging influence treatment options?

A

staging determines whether patients are given additional chemotherapy

stage 3 or 4 cases are given chemotherapy to improve chances of survival

42
Q

What type of blood test is usually used as a follow-up treatment for colorectal cancer patients?

A

CEA (carcinoembryonic antigen) blood test

it is used to help diagnose and manage certain types of cancers

using this blood test can show whether a particular cancer treatment is working

43
Q

What is Hartmann’s procedure and why is it used in colorectal cancer?

A

it is also known as a proctosigmoidectomy

surgical resection of the rectosigmoid colon with closure of the anorectal stump and formation of an end colostomy

44
Q

What are metastases?

A

metastasis is when cancer spreads to a different body part from where it started

metastases is the pleural of metastasis

45
Q

What routes do tumours metastasize by?

A

cancer cells break away from the main tumour and enter the blood or lymphatic system

cancer cells may also break off of the primary tumour and grow in a nearby area