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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
What are the features of a colorectal adenoma that indicate it is at risk of malignancy and invasion?
``` Size: <1% if <1cm vs 10% of >2cm • Number: 3 or more • Architecture: villous component • Dysplasia: high-grade ``` presence of an invasive carcinoma
26
What is the Adenoma-Carcinoma Sequence and how long does it take to progress?
Time for progression: 5 to >20 years • Includes various mutations: APC, Beta-catenin, KRAS and TP53 • Associated with microsatellite instability
27
Which type of cancer is most commonly responsible for colorectal cancer?
ADENOCARCINOMA
28
What is the peak age incidence for colorectal cancer? What which age of presentation would a genetic cause be likely?
60-79 years <20% before age 50 if before age 40, probably related to syndrome
29
On which side of the body is colorectal cancer most common? On which side does colorectal cancer present latest?
Left sided more than right sided | Present later on the right side
30
What are the risk factors for colorectal cancer?
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
What are the symptoms of colorectal cancer? (difference between left and right)
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
Which tests are conducted for colorectal cancer screening?
Colonoscopy (Flexible sigmoidoscopy), Faecal occult blood test, Faecal Immunochemical Test
33
Which features would require a patient to be referred to the 2 week colorectal cancer pathway?
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
What are the common metastatic sites for colon cancer?
``` lymph nodes liver (most common) peritoneum lung ovaries ```
35
What is the general prognosis for someone with colorectal cancer?
5 year survival: 40-60% Most recurrences are within two years
36
What are poor prognostic features of colorectal cancer? (6)
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
What is the staging for colorectal cancer?
``` 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
Causes of angular stomatitis?
Iron deficiency anaemia | Crohn's
39
What does Tumour budding mean?
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
Which investigations (imaging)are conducted in someone with suspected colorectal cancer (not screening)
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
What is the difference between a Colonoscopy and a Flexible sigmoidoscopy?
Colonoscopy ends at the terminal ileum Flexible sigmoidoscopy ends at the splenic flexure
42
What are the disadvantages of conducting a CT pneumocolon & CT abdomen/pelvis over a colonoscopy?
Does not allow removal of polyps or biopsy of lesions. Some lesions may be missed.
43
Which FURTHER investigations are conducted on a patient suspected to have colorectal cancer?
``` 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
List the different types of colorectal cancer
``` Adenocarcinoma and subtypes • Adenosquamous carcinoma • Squamous cell carcinoma • Neuroendocrine carcinoma ```
45
Which types of polyps are malignant, which are not and which have the potential to be malignant.
Malignant - All adenomatous polyps Non malignant Inflammatory Hyperplastic Hamartomatous Potential - Sessile hyperplastic polyps
46
What are the hereditary syndromes associated with adenomatous colorectal polyps?
Lynch syndrome - Adenomatous polyposis syndromes including Familial adenomatous polyposis (FAP) Gardner syndrome Turcot syndrome MUTYH polyposis All autosomal dominant conditions
47
Describe lynch syndrome. On which side does it usually present?
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
Describe FAP
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
What is the most common treatment for colorectal cancer?
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
List the different surgical types and when they are used?
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
How can you roughly differentiate a colostomy from an ileostomy?
Colostomy-left hand side | Ileostomy - Right hand side
52
Which gene is responsible for FAP?
adenomatous polyposis coli
53
Which type of polyp is most likley to cause intussusception?
Juvenile polyps
54
List 3 differential diagnosis for colorectal cancer
Diverticulitis IBD Large bowel lymphoma

MET3A (14 decks)

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