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

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2
Q

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

A

86%

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3
Q

What are predisposing factors to the development of colorectal carcinoma?

A
  • Neoplastic polyps
  • IBD
  • Genetic predisposition
  • Diet
  • Increased alcohol
  • Smoking
  • Previous cancer
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4
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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5
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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6
Q

What is familial adenomatous polyposis?

A

An autosomal dominant condition arising from germline mutations of the APC gene located on chromosome 5q21-q22.

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7
Q

What is the penetrance of FAP?

A

Virtually 100%

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8
Q

What are the main characteristic findings in FAP?

A

Presence of hundreds to thousands of colorectal and duodenal adenomas

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9
Q

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

A

39

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10
Q

What should people affected with FAP be offered?

A

Prophylactic colectomy before the age of 20

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11
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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12
Q

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

A

Duodenal adenomas which progress to cancer

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13
Q

What is hereditary non-polyposis colon cancer?

A

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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14
Q

Where do tumours in HNPCC tend to occur?

A

Right colon

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15
Q

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

A

70-80%

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16
Q

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

A
  • Stomach
  • Small intestine
  • Bladder
  • Skin
  • Brain
  • Hepatobiliary
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17
Q

What symptoms might someone with colorectal cancer have?

A
  • Rectal bleeding
  • Diarrhoea
  • Tiredness
  • Weight loss/anorexia
  • Abdominal pain
  • Tenesmus
  • Obstruction
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18
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
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19
Q

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

A

Often asymptomatic

  • Weight loss
  • Iron deficiency Anaemia
  • Abdominal pain
  • Obstruction less likely
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20
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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21
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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22
Q

Where does colorectal cancer most commonly spread?

A
  • Liver
  • Lungs
  • Brain
  • Bone
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23
Q

What is the pathology of colorectal cancer?

A

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

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24
Q

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

A
  • Bloods - FBC, LFT
  • Faecal occult blood test
  • Sigmoidoscopy/colonoscopy
  • CT colonography
  • Liver MRI/US
  • PET scan
  • Consider DNA test if FAP
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25
Q

What is faecal occult blood testing used for?

A

Mass population screeing

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26
Q

What might FBC show in someone with colorectal cancer?

A

Iron deficiency anaemia

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27
Q

What might LFTs show in someone with colorectal cancer?

A

Deranged if liver mets present

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28
Q

What is CEA?

A

Carcinoembryonic antigen

Used for follow-up, rising levels suggest recurrence

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29
Q

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

A

Colonoscopy/Sigmoidoscopy

30
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
31
Q

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

A

Look for liver mets

32
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
33
Q

What do adenomcarcinomas of the bowel arise from?

A

Adenomas

34
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’

35
Q

How do adenomas progress to cancers?

A

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

36
Q

What is a polyp?

A

Abnormal growth of tissue from the colonic mucosa

37
Q

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

A

80%

38
Q

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

A

Rectum and sigmoid colon - most others are asymptomatic

39
Q

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

A
  • Local
  • Lymphatic
  • Haematogenous - lung, liver, bone
  • Trancoelomic
40
Q

What does Tis stand for in terms of TNM staging?

A

Carcinoma in situ

41
Q

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

A

Invasion into the submucosa

42
Q

What does T2 represent in terms of colorectal cancer staging?

A

Invading muscularis propria

43
Q

What does T3 staging mean in colorectal cancer?

A

Invading subserosa and beyond

44
Q

What does T4 staging of a colorectal cancer mean?

A

Invasion of adjacent structures

45
Q

What does N1 staging of colorectal cancer indicate?

A

1-3 regional lymph nodes affected

46
Q

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

A

>3 regional nodes affected

47
Q

What is stage 0 CRC?

A

Carcinoma in situ (Tis)

48
Q

What is stage 1 CRC?

A
  • T1, N0, M0 - submucosa
  • T2, N0, M0 - muscularis propria
49
Q

What is stage II CRC?

A
  • T3, N0, M0 - invades subserosa
  • T4, N0, M0 - invading other organs
50
Q

What is stage III CRC?

A

Any T, N1, MO - regional lymph node involvement

51
Q

What is stage IV CRC?

A

Any T, any N, M1 - distant metastases

52
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%
53
Q

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

A

Right hemicolectomy

54
Q

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

A

Right hemicolectomy

55
Q

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

A

Right extended hemicolectomy

56
Q

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

A

Left hemicolectomy

57
Q

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

A

Left hemicolectomy

58
Q

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

A

Sigmoid colectomy

59
Q

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

A

Abdomino-perineal resection

60
Q

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

A

Anterior resection

61
Q

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

A

Anterior resection

62
Q

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

A

Colostomy

63
Q

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

A

Hartmann’s procedure

64
Q

When would endoscopic stening be used to manage colorectal cancer?

A
  • Palliation of malignant obstruction
  • Bridge to surgery in acute obstruction
65
Q

When is radiotherapy used in colorectal cancer?

A
  • Most for palliation in colonic cancer
  • Pre-op in rectal cancer
  • Post-op rectal with risk of high recurrence
66
Q

When would you consider using chemotherapy in treating colorectal cancer?

A

Potentially post-op stage III and some stage II

67
Q

How could you manage a rectal coloractal cancer?

A
  • Pre-op radiotherapy
  • Abdomino-perineal resection
68
Q

Why is radiotherapy not helpful for in colorectal cancer?

A

Cancer proximal to the rectum - difficulty delivering sufficient dose

69
Q

What would you use endoscopic or local resection to treat?

A

Polyps and Stage I cancer

70
Q

How would you screen for colorectal cancer?

A
  • Faecal occult blood test
  • Colonoscopy
  • Flexible sigmoidoscopy
  • CT colonography
71
Q

What are features of a rectal cancer?

A
  • Rectal bleeding
  • Changes in bowel habit
  • Tenesmus
  • Anal/perianal pain
  • Faecal incontinence
  • Fistula formation
72
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