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MET3A > Colorectal cancer > Flashcards

Colorectal cancer Flashcards

1
Q

Where does the colon start and end?

A

terminal ileum to anal canal

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2
Q

How long is the colon?

A

1-1.5m long

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3
Q

Name the different parts of the colon

A

Caecum -> Ascending Colon -> Hepatic flexure ->Transverse colon -> Splenic flexure -> Descending colon, sigmoid -> Rectum

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4
Q

Which arteries supply which regions of the colon?

A

Superior mesenteric artery (caecum - splenic flexure)

Inferior mesenteric artery (remainder of colon - rectum)

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5
Q

What are the common symptoms of right sided polyps?

A

less overt blood, intussusception (rare, one part of intestines goes into the other),
constipation, diarrhoea, obstruction

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6
Q

What are the symptoms of left sided polyps?

A

frank blood, constipation, diarrhoea,

obstruction

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7
Q

What are inflammatory polyps? Which conditions are the often associated with?

A

Polys caused by repeated cycles of injury and healing

non-neoplastic

They consist of a mix of epithelial and stromal elements

may be associated with inflammatory bowel disease, surgical anastomosis or with other causes of inflammation (eg: ischaemic colitis, infection)

incidence of ~10-20% in patients with ulcerative colitis

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8
Q

What are the histological features of a inflammatory poly?

A

may be relatively normal with a polypoid shape

may have ulceration, erosion and distortion of the normal crypt architecture

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9
Q

What is a hyperplastic poly? How large are they usually and on which side do they most often present?

A 
Serrated polyp (saw tooth appearance)
Due to reduced cell turn over 
Non dysplastic (non cancerous)
asymptomatic 
Most common type of polyp
Up to 5mm in size, rarely greater than 10mm
More common on the Left sided
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10
Q

Hyperplastic lesions are usually not malignant. Under which circumstances are hyperplastic lesions at an increased risk of becoming malignant?

A

If they are sessile

SESSILE SERRATED LESIONS/POLYPS/ADENOMAS

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11
Q

What are hyperplastic sessile serrated polyps? How large are they?

A

They are Neoplastic masses with premalignant features (have the potential to be malignant)
Account for up to 9% of all colorectal polyps
>10mm in size (larger than nomal hyperplastic polyps)

SERRATED architecture, with crypt dilatation and MAY HAVE low-grade or high-grade dysplasia.

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12
Q

Which mutation is hyperplastic sessile serrated polyps associated with?

A 
BRAF mutation (microsatellite
instability)
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13
Q

What are Hamartomatous polyps, which mutations lead to their development, in which age group do they occur in and what do they often look like?

A

Polys that occur due to germ line mutations in tumour suppressor genes or proto oncogenes. They tend to occur in children and young adults. Mostly perduculated?

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14
Q

Name the 2 main types of Hamartomatous polyps?

A

Peutz-Jegher

Juvenile polyps

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15
Q

What are Peutz-Jegher polyps?

A

Autosomal dominant defect
Cuases multiple Hamartomatous polyp and mucocutaneous pigmentation

muscularis mucosa

Usually Manifest early (with first or second decade of life) - but can occur at any age
Does not undergo malignant transformation

But condition causes an increased life time risk of cancer
CAN develop into dysplasia and adenocarcinoma

Increases life time risk of developing breast, cervical, uterine, pancreas, and lung cancer

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16
Q

What is the criteria for the diagnosis of PEUTZ-JEGHER SYNDROME?

A

(a) 3 or more PJ polyps
(b) any number of PJ polyps with family history of PJS
(c) characteristic mucocutaneous pigmentation with family history of PJS
(d) any number of PJ polyps and mucocutaneous pigmentation

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17
Q

Which mutation is responsible for Peutz-Jegher polyps?

A

STK 11 mutation - tumour suppressor gene

On chromosome 19

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18
Q

What are Juvenile polyps, describe histological features, size, and usual age of onset?

A

Polyps which effect children under the age of 5.

Sessile or pedunculated, 5-50mm in size

similar to inflammatory polyps but usually have
cystically dilated crypts

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19
Q

What are the different types of Juvenile polyps ?

A

One polyp (no family history) = Retention polyp

Juvenile polyposis Syndrome= 5 or more juvenile polyps in Colo rectum

Or

Juvenile polyps throughout GI tract or any
number of juvenile polyps + family history.

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20
Q

What is the inheritance patter of Juvenile polyps and Peutz-Jegher polyps?

A

Autosomal dominant

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21
Q

There are 3 types of adenomas, name them

A

Tubular, villous, tubulovillous

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22
Q

What is the most common type of adenoma in colorectal cancer?

A

Tubular adenomas?

23
Q

Which gene mutation is found in Juvenile polyps?

A

SMAD 4 gene

24
Q

Which type of colorectal adenoma has the highest malignant potential?

A

Villous adenoma

25
Q

What are the features of a colorectal adenoma that indicate it is at risk of malignancy and invasion?

A 
Size: <1% if <1cm vs 10% of >2cm
•
 Number: 3 or more
•
 Architecture: villous component
•
 Dysplasia: high-grade

presence of an invasive carcinoma

26
Q

What is the Adenoma-Carcinoma Sequence and how long does it take to progress?

A

Time for progression: 5 to >20 years
•
Includes various mutations: APC, Beta-catenin, KRAS
and TP53
•
Associated with microsatellite instability

27
Q

Which type of cancer is most commonly responsible for colorectal cancer?

A

ADENOCARCINOMA

28
Q

What is the peak age incidence for colorectal cancer? What which age of presentation would a genetic cause be likely?

A

60-79 years

<20% before age 50

if before age 40, probably related to syndrome

29
Q

On which side of the body is colorectal cancer most common? On which side does colorectal cancer present latest?

A

Left sided more than right sided

Present later on the right side

30
Q

What are the risk factors for colorectal cancer?

A

older age

obesity

Smoking

physical inactivity

alcohol consumption

IBD

family history

Adenomatous polyposis syndromes

FAP (Familial adenomatous polyposis)
lynch syndrome, juvenile polyposis, PJS

DIETARY RISK FACTORS

low fibre, increased beef (red meat)
consumption

31
Q

What are the symptoms of colorectal cancer? (difference between left and right)

A

Right: Often presents late, abdominal pain, anaemia, pain, Mass in right iliac fossa, occult bleeding

Left: change in bowel habit (pencil like stool), rectal bleeding, Presents earlier, may present with bowel obstruction, tenesmus, mass in lower iliac fossa or PR exam

Patient may be asymptomatic

Other include

  • Unintentional weight loss
  • Iron deficiency anaemia
  • Change in bowel habits
  • Abdominal masses
  • Blood in stool
  • Tiredness (malaise)
  • Tenesmus (feeling of incomplete bowel evacuation)
32
Q

Which tests are conducted for colorectal cancer screening?

A

Colonoscopy (Flexible sigmoidoscopy),

Faecal occult blood test,

Faecal Immunochemical Test

33
Q

Which features would require a patient to be referred to the 2 week colorectal cancer pathway?

A

Aged 40 and over with unexplained weight loss and abdominal pain

Aged 50 and over with unexplained rectal bleeding

Aged 60 and over with:
Iron-deficiency anaemia or
Changes in their bowel habit

Patients with tests showing occult blood in their faeces

Patients with rectal or abdominal mass

Consider in any patient under 50 with -

  • Abdominal pain or
  • Change in bowel habit or
  • Weight loss or
  • Iron-deficiency anaemia
34
Q

What are the common metastatic sites for colon cancer?

A 
lymph nodes
 liver (most common)
 peritoneum
 lung
 ovaries
35
Q

What is the general prognosis for someone with colorectal cancer?

A

5 year survival: 40-60%

Most recurrences are within two years

36
Q

What are poor prognostic features of colorectal cancer? (6)

A

High stage,

positive margins - Cancer cells come right out to the edge of the removed tissue

Poor differentiation- Tumour cells no longer look like normal cells - indicates high grade tumour

Tumour budding

Tumour perforation- Tumour has caused a hole in he bowel so cancer cells can spread

Involvement of
peritoneal cavity - Cancer has spread to the peritoneum (metastasis)

37
Q

What is the staging for colorectal cancer?

A 
Tx: Primary tumour cannot be assessed
T0: No evidence of primary tumour
Tis: Ca in-situ
T1: Tumour invades submucosa
T2: Tumour invades muscularis propria
T3: Tumour invades through muscularis propria
T4:
T4a: Tumour invades serosa/visceral peritoneum
T4b: Tumour directly invades or adheres to adjacent organs or structures
Nx: nodes cannot be
assessed
N1: metastasis in 1-3
nodes (N1a=1;
N1b=2,3; N1c: soft
tissue deposit; no
nodes)
N2: metastasis in 4 or
more nodes (N2a:
4-6; N2b: 7 or more)

M0- No distant metastasis by imaging; no evidence of tumor in other sites or organs
M1- instant metastasis

1a - Metastasis confined to 1 organ or site without peritoneal metastasis. Also non regional lymph node spread

M1B Metastasis to 2 or more sites or organs is identified without peritoneal metastasis

M1C - Metastasis to the peritoneal surface is identified alone or with other site or organ metastases

38
Q

Causes of angular stomatitis?

A

Iron deficiency anaemia

Crohn’s

39
Q

What does Tumour budding mean?

A

The presence of single tumour cells or small tumour clusters of up to five cells. These “buds” are detached from the main mass and are

usually located in the stroma at the invasive front of the tumor.

40
Q

Which investigations (imaging)are conducted in someone with suspected colorectal cancer (not screening)

A

Colonoscopy (to the terminal ilium)

Flexible sigmoidoscopy may also be used in individuals not able to undergo colonoscopy, with left sided lesions

In those not suitable for, or declining endoscopy a CT pneumocolon (CT virtual colonoscopy) may be used to identify lesions. Should also be used for the with right sided features when full colonoscopy can not be conducted

In those unable to tolerate a CT pneumocolon, a plain CT abdomen/pelvis (with or without contrast)

41
Q

What is the difference between a Colonoscopy and a Flexible sigmoidoscopy?

A

Colonoscopy ends at the terminal ileum

Flexible sigmoidoscopy ends at the splenic flexure

42
Q

What are the disadvantages of conducting a CT pneumocolon & CT abdomen/pelvis over a colonoscopy?

A

Does not allow removal of polyps or biopsy of lesions.

Some lesions may be missed.

43
Q

Which FURTHER investigations are conducted on a patient suspected to have colorectal cancer?

A 
Bloods-
FBC
Serum iron, transferrin saturation, TIBC
Renal function
LFT
Clotting screen
Tumour markers (NOT FIRST LINE) used to monitor treatment or as a marker of recurrence or to assess disease burden - not specific enough to use for a diagnosis 
Carcinoembryonic antigen (CEA)

CT chest abdo and pelvis with contrast- Assess disease burden and sites of metastasis

MRI Mesorectum rectum- Better stage rectal tumours

Endoanal USS: Better stage rectal tumours

PET/CT - not routinely used, may help with staging when recurrence occurs

MRI liver- Assess liver metastasis

44
Q

List the different types of colorectal cancer

A 
Adenocarcinoma and subtypes
•
 Adenosquamous carcinoma
•
 Squamous cell carcinoma
•
 Neuroendocrine carcinoma
45
Q

Which types of polyps are malignant, which are not and which have the potential to be malignant.

A

Malignant -

All adenomatous polyps

Non malignant

Inflammatory
Hyperplastic
Hamartomatous

Potential -
Sessile hyperplastic polyps

46
Q

What are the hereditary syndromes associated with adenomatous colorectal polyps?

A

Lynch syndrome -

Adenomatous polyposis syndromes including

Familial adenomatous polyposis (FAP)

Gardner syndrome

Turcot syndrome

MUTYH polyposis

All autosomal dominant conditions

47
Q

Describe lynch syndrome. On which side does it usually present?

A

Most common inherited cause (Hereditary nonpolyposis colorectal cancer)

Caused by mutation to DNA mis match repair genes

Does not cause extensive polyps

Usually right sided

Increases risk of other malignancies e.g endometrial, ovary, small bowel, stomach and liver

48
Q

Describe FAP

A

Caused by a mutation in the adenomatous polyposis coli (APC) gene

Usually presents in adolescents

Patients develop many colonic polyps (>100)

If not treated 90% will develop colon cancer before the age of 45

Increases risk of other cancers e.g. thyroid, pancreatic and hepatoblastomas

49
Q

What is the most common treatment for colorectal cancer?

A

Surgical resection with a temporary stoma to to protect the anastomosis between the proximal and distal segments of remaining bowel

Stoma is usually reversed after several months

50
Q

List the different surgical types and when they are used?

A

Tumour in cecum or ascending colon = Right hemi-colectomy

Cancer on the right side involving the transverse colon = Extended right hemicolectomy

Anterior resection and loop iliostomy - used for right recal tumours (greater than 5cm from the anal margin) (loop ileostomy is reversed)

Left hemicolectomy and end colostomy - for left sided tumours

51
Q

How can you roughly differentiate a colostomy from an ileostomy?

A

Colostomy-left hand side

Ileostomy - Right hand side

52
Q

Which gene is responsible for FAP?

A

adenomatous polyposis coli

53
Q

Which type of polyp is most likley to cause intussusception?

A

Juvenile polyps

54
Q

List 3 differential diagnosis for colorectal cancer

A

Diverticulitis
IBD
Large bowel lymphoma

MET3A (14 decks)

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