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Gwen - GI and General surgery > GI: Colorectal polyps and cancer > Flashcards

GI: Colorectal polyps and cancer Flashcards

1
Q

What is the most common type of colonic cancer?

A

Adenocarcinoma - with variably differentiated glandular epithelium with mucin production

Two main tyoes are: Tubular and Villous

(rest are neuroendocrine (release serotonin) and rarely primary lymphoma)

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2
Q

Describe the adenoma-carcinoma sequence

A

Normal epithelium

Small adenoma (polyp)

Large adenoma/polyp

Invasive adenocarcinoma (occurs in around 10%)

Metastases

This process can take 10-15 years

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3
Q

What proportion of presentation of colorectal cancer are over the age of 60?

A

86%

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4
Q

What are predisposing factors to the development of colorectal carcinoma?

A
  • 85% are sporadic with no gamilai/genetic influence. RF:
    • Age >40
    • Male
    • Inflammatory bowel disease
    • Previous adenoma/CRC/Neoplastic polyps
    • Environmental influences
      • Diet - reduced fibre, low calcium, increased red meat
      • Alcohol
      • Smoking
      • Physical inactivity
      • Obesity
  • Genetic predisposition
    • ​HNPCC
    • FAP
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5
Q

What dietary factors can increase the risk of developing colon cancer?

A
  • Low-fibre
  • High red and processed meat content
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6
Q

What genetic problems can predispose to the development of colorectal cancer?

A
  • Familial adenomatous polyposis (FAP)
  • Hereditary non-polyposis colon cancer (HNPCC; Lynch syndrome)
  • Peutz-Jeghers syndrome
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7
Q

What is familial adenomatous polyposis?

A

An autosomal dominant condition arising from germline mutations of the APC gene located on chromosome 5q21-q22 (tumour supressor gene)

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8
Q

What is the penetrance of FAP?

A

Virtually 100%

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9
Q

What are the main characteristic findings in FAP?

A

Presence of hundreds to thousands of colorectal and duodenal adenomas (excess growth of adenomatous tissue). High risk of amlaignant change in early adulhood.

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10
Q

What is the average age of developing colon cancer from FAP?

A

39

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11
Q

Screening in FAP

A

Annual colonscopy from 10-12 years

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12
Q

What should people affected with FAP be offered?

A

Prophylactic colectomy before the age of 20

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13
Q

What surgical options are available for treating FAP?

A
  • Colectomy + Ileorectal anastamosis
  • Restorative proctocolectomy or pouch procedure with complete removal of rectal mucosa.
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14
Q

What is the commonest cause of death in colectomised patients with FAP?

A

Duodenal adenomas which progress to cancer

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15
Q

What is hereditary non-polyposis colon cancer?

A

Autosomal dominant

A disease caused by a mutation in one of the DNA mismatch repair genes, usually hMSH2 or hMLH1 but others (hMSH6, PMS1 and PMS) have been reported.

The defect in function causes naturally occurring highly repeated short DNA sequences known as microsatellites to be shorter or longer than normal, a phenomenon called microsatellite instability (MSI).

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16
Q

Where do tumours in HNPCC tend to occur?

A

Right colon

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17
Q

Typical onset of CRC in HNPCC

A

<10 years

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18
Q

Screening in HNPCC

A

Biennial colonscopy from age 25

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19
Q

What is the lifetime risk of developing cancer if you have HNPCC?

A

70-80%

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20
Q

What cancers (other than colon cancer) are common in HNPCC?

A
  • Endometrial (COMMONEST)
  • Stomach
  • Small intestine
  • Pancreas
  • Bladder
  • Skin
  • Brain
  • Hepatobiliary
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21
Q

What symptoms might someone with colorectal cancer have?

A
  • Change in bowel habit
    • Rectal bleeding
    • Diarrhoea
    • Tenesmus
  • Tiredness
  • Weight loss/anorexia
  • Abdominal pain (colicky)
  • Iron deficiency anaemia
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22
Q

What features might indicate someone has a colorectal cancer in the left side of their colon?

A
  • PR Exam - bleeding/mucus, Mass
  • Altered bowel habits/Obstruction
  • Tenesmus
  • Mass in the L iliac fossa/PR on exam
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23
Q

What features might suggest a colorectal cancer is on the right side of the colon/caecum?

A

Often asymptomatic

  • Iron deficiency Anaemia
  • Abdominal pain
  • Obstruction less likely
  • Occult bleeding
  • Mass in R iliac fossa
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24
Q

What features can occur in either left or ride sided colon cancer?

A
  • Abdominal mass
  • Signs of perforation
  • Signs of haemorrhage
  • Signs of fistula formation
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25
Q

Differentials of colorectal cancer

A
  • Inflammatory bowel disease
    • Average onset younger (40-60), typically presents with diarrhoea continuing blood/mucous
  • Haemorrhoids
    • Bright red rectal bleeding on stool - rarely presents with abdo discomfort, weight loss, altered bowel habits
  • Diverticulitis
    • Can present with blood in stool and changed bowel habit but likely to have systemic signs of inflammation
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26
Q

Refer for immediate investigation of bowel cancer if

A

>40 with unexplained weight loss and abdo pain

>50 unexplained rectal bleeding

>60 iron defieincy anaemia or changes in bowel habit

+ve occult faecal blood test

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27
Q

What type of bowel habit change most commonly occurs in colon cancer?

A

Diarrhoea, although can have constipation if obstructed

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28
Q

Where does colorectal cancer most commonly spread?

A
  • Liver
  • Lungs
  • Brain
  • Bone
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29
Q

What is the pathology of colorectal cancer?

A

Polypoid mass with ulceration, which directly infiltrates through the bowel wall

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30
Q

What investigations might you consider doing in someone with suspected colorectal cancer?

A
  • Faecal occult blood test
  • Sigmoidoscopy/colonoscopy
  • Bloods - FBC (microcytic), LFT (liver mets), Raised CEA (not diagnostic due to poor specifity but should be monitored for disease progression)
  • Imaging
    • Radiology
      • CT colonography
      • Barium enema
      • CT abdo pelvis
      • Liver MRI/US
      • PET scan
    • Endoscopy
      • COLONOSCOPY AND BIOPSY (flexible sigmoidoscopy if comorbidities/intolerance)
  • Consider DNA test if FAP
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31
Q

What is faecal occult blood testing used for?

A

Mass population screeing

(Screening = FOBT, colonoscopy)

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32
Q

What might FBC show in someone with colorectal cancer?

A

Iron deficiency anaemia

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33
Q

What might LFTs show in someone with colorectal cancer?

A

Deranged if liver mets present

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34
Q

What is CEA?

A

Carcinoembryonic antigen

Used for follow-up, rising levels suggest recurrence

35
Q

What is the gold standard for investigation of someone with features of colorectal cancer?

A

Colonoscopy/Sigmoidoscopy

36
Q

What is PET scanning used for when investigating someone for colorectal cancer?

A
  • Looking for distant mets
  • Evaluation of suspicious lesions on CT/MRI
37
Q

Why might you do a liver MRI/US in colorectal cancer?

A

Look for liver mets

38
Q

What are red flag symptoms which would raise your suspicion of colorectal cancer?

A
  • Palpable rectal mass (any age)
  • Iron deficiency anaemia in men of any age/non-menstruating women of any age
  • Rectal bleeding and change of bowel habit for more than six weeks in patients > 60
  • Rectal bleeding for 6 weeks or more in anybody over 50
39
Q

What do adenomcarcinomas of the bowel arise from?

A

Adenomas

40
Q

What are adenomas?

A

An adenoma is a benign, dysplastic tumour of columnar cells or glandular tissue. They have tubular, tubulovillous or villous morphology. The vast majority of adenomas are not inherited and are termed ‘sporadic’

41
Q

How do adenomas progress to cancers?

A

Progress via increasing grades of dysplasia due to progressive accumulation of genetic changes

42
Q

What is a polyp?

A

Abnormal growth of tissue from the colonic mucosa

43
Q

What percentage does removing polyps and subsequent surveillance reduce the risk of developing cancer by?

A

80%

44
Q

Polyps in which section of the colon can present with rectal bleeding?

A

Rectum and sigmoid colon - most others are asymptomatic

45
Q

What are the main modes of spread of a colorectal cancer?

A
  • Local
  • Lymphatic
  • Haematogenous - lung, liver, bone
  • Trancoelomic
46
Q

What does Tis stand for in terms of TNM staging?

A

Carcinoma in situ

47
Q

What does T1 stand for in terms of staging of colorectal carcinoma?

A

Invasion into the submucosa

48
Q

What does T2 represent in terms of colorectal cancer staging?

A

Invading muscularis propria

49
Q

What does T3 staging mean in colorectal cancer?

A

Invading subserosa and beyond

50
Q

What does T4 staging of a colorectal cancer mean?

A

Invasion of adjacent structures

51
Q

What does N1 staging of colorectal cancer indicate?

A

1-3 regional lymph nodes affected

52
Q

What does N2 indicate in terms of staging of a CRC?

A

>3 regional nodes affected

53
Q

What is stage 0 CRC?

A

Carcinoma in situ (Tis)

54
Q

What is stage 1 CRC?

A
  • T1, N0, M0 - submucosa
  • T2, N0, M0 - muscularis propria
55
Q

What is stage II CRC?

A
  • T3, N0, M0 - invades subserosa
  • T4, N0, M0 - invading other organs
56
Q

What is stage III CRC?

A

Any T, N1, MO - regional lymph node involvement

57
Q

What is stage IV CRC?

A

Any T, any N, M1 - distant metastases

58
Q

What are the top 3 most common locations for colorectal cancers to occur?

A
  1. Rectum - 27%
  2. Sigmoid colon - 20%
  3. Caecum - 14%
59
Q

Overveiw of surgical maangement of colorectal cancer

A

Regional colectomy with adequate margins. Primary anastomosis or stoma.

60
Q

What surgical management would you consider to treat caecal colorectal cancer?

A

Right hemicolectomy

61
Q

What surgical management would you consider to treat colorectal cancer of the ascending colon?

A

Right hemicolectomy

62
Q

What surgical management would you consider to treat colorectal cancer of the proximal transverse colon?

A

Right extended hemicolectomy

63
Q

What surgical management would you consider to treat colorectal cancer of the descending colon?

A

Left hemicolectomy

64
Q

What surgical management would you consider to treat colorectal cancer of the distal transverse colon?

A

Left hemicolectomy

65
Q

What surgical management would you consider to treat colorectal cancer of the sigmoid colon?

A

Sigmoid colectomy

66
Q

What surgical management would you consider to treat colorectal cancer of the lower sigmoid (lower rectum)?

A

Abdomino-perineal resection

(AP resection) - permanent colostomy and removal of retum and anus

67
Q

What surgical management would you consider to treat colorectal cancer of the rectum (high rectal, low sigmoid)?

A

Anterior resection

68
Q

What surgical management would you consider to treat colorectal cancer of the rectum?

A

Anterior resection

69
Q

What will someone have permanently following a abdomino-perineal resection?

A

Colostomy

70
Q

What procedure would you consider doing in someone with emergency bowel obstruction or perforation?

A

Hartmann’s procedure - involves surgical resection of the rectosigmoid colon with closure of the anorectal stump and formation of an end colostomy.

71
Q

When would endoscopic stening be used to manage colorectal cancer?

A
  • Palliation of malignant obstruction
  • Bridge to surgery in acute obstruction
72
Q

When is radiotherapy used in colorectal cancer?

A
  • Most for palliation in colonic cancer
  • Pre-op in RECTAL CANCER (risk of damage to small bowel in colon cancer)
  • Post-op rectal with risk of high recurrence
73
Q

When would you consider using chemotherapy in treating colorectal cancer?

A

Potentially post-op stage III and some stage II, positive LN histology

74
Q

What chemotherapy is typically used in CRC

A

5-FU (Fluorouracil)

75
Q

How could you manage a rectal coloractal cancer?

A
  • Pre-op radiotherapy
  • Abdomino-perineal resection
76
Q

Why is radiotherapy not helpful for in colorectal cancer?

A

Cancer proximal to the rectum - difficulty delivering sufficient dose

77
Q

What would you use endoscopic or local resection to treat?

A

Polyps and Stage I cancer

78
Q

How would you screen for colorectal cancer?

A
  • Faecal occult blood test
  • Colonoscopy
  • Flexible sigmoidoscopy
  • CT colonography
79
Q

What are features of a rectal cancer?

A
  • Rectal bleeding
  • Changes in bowel habit
  • Tenesmus
  • Anal/perianal pain
  • Faecal incontinence
  • Fistula formation
80
Q

What is the general resection margin used in surgery for colorectal tumours?

A

2cm either side of the main tumour, unless rectal which they use 5cm as cut off

81
Q

Describe the Scottish Bowel Screening Programme

A

Age 50-74 years

If age >75, you can still take a test every 2 years if you want

FOBT every 2 years

If FOBT +ve then colonoscopy

Approx 15% decrease in relative risk of CRC mortality

82
Q

Describe Dukes classificaiton for CRC

A

A: Invasion confined to muscosa - 90% 5 year survival

B: Infiltration through muscle - 70% 5 year survival

C: Lymph node involvement - 30% 5 year survival

D: Distant metastases - 5% 5 year survival

83
Q

High risk groups for developping CRC

A
  • FAP
  • HNPCC
  • FH CRC
    • High risk = CRC in 3 family members, mean age <60: 5 year colonscopy from age 50
    • Moderate risk = CRC in 2 family memebrs >60 or 1 family memebr <50: once only colonscopy at age 55
  • IBD
    • Surveillance colonscopy 10 years post diagnosis
  • Previous CRC
    • 5 yearly colonscopy
  • Previous adenomas
    • Dependant on number of polyps, size, degree of dysphasia

Gwen - GI and General surgery (44 decks)

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