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General Surgery > Colorectal cancer > Flashcards

Colorectal cancer Flashcards

1
Q

how common is colorectal cancer?

A

4th most common cancer in UK - 40,000 new cases a year

2nd highest mortality of any cancer

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2
Q

where does colorectal cancer originate from?

A

epithelial cells lining the colon or rectum and is most commonly an adenocarcinoma
(rare lymphoma, carcinoid and sarcoma)

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3
Q

how to most colorectal cancers develop?

A

progression of normal mucosa to colonic adenoma to invasive adenocarcinoma
adenomas can be present for 10 years before they become malignant
progression to adenocarcinoma occurs in 10% of adenomas

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4
Q

what are the genetic mutations associated with predisposing individuals to colorectal cancer?

A

Adenomatous polyposis coli (APC)

Hereditary nonpolyposis colorectal cancer (HNPCC)

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5
Q

what is APC?

A

Adenomatous polyposis coli
tumour suppressor gene, mutation of APC results in growth of adenomatous tissue associated with Familial Adenomatous Polyposis (FAP)

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6
Q

what is HNPCC?

A

DNA mismatch repair gene, mutation to HNPCC leads to defects in DNA repair, associated with Lynch syndrome

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7
Q

risk factors of colorectal cancer

A 
75% are sporadic 
increasing age
family history 
inflmmatory bowel disease 
low fibre diet 
high processed meat intake 
smoking 
high alcohol intake
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8
Q

clinical features of colorectal cancer

A 
change in bowel habit 
rectal bleeding 
weight loss (associated with metastatic disease)
abdominal pain 
iron-deficient anaemia
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9
Q

features of right-sided colon cancer

A

abdominal pain
occult bleeding/anaemia
mass in RIF
often presents late

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10
Q

features of left-sided colon cancer

A

rectal bleeding
change in bowel habit
tenesmus
mass in LIF or on PR exam

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11
Q

what is the NICE guidance on referring ? bowel cancer?

A
  1. ≥40yrs with unexplained weight loss and abdominal pain
  2. ≥50yrs with unexplained rectal bleeding
  3. ≥60yrs with iron‑deficiency anaemia or change in bowel habit
  4. Positive occult blood screening test
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12
Q

what are some differentials for colon cancer?

A

inflammatory bowel disease - average age of onset 20-40 yrs, typically presents with bloody, mucusy diarrhoea
haemorrhoids - bright red rectal bleeding on surface of stool but rarely presents with pain, altered bowel habits or weight loss

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13
Q

when is screening for bowel cancer offered in the uk?

A

every 2 years to men and women aged 60-75

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14
Q

what test is used in bowel cancer screening?

A

faecal immunochemistry test (FIT)
(supersedes faecal occult test)
uses antibodies against human haemoglobin to detect blood in faces

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15
Q

how does the FIT work?

A

uses antibodies against human haemoglobin to detect blood in faces

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16
Q

what happens if a patients FIT sample is positive?

A

offered an appointment with a specialist nurse to further investigate via colonoscopy

17
Q

The NHS Bowel Cancer Screening Programme has increased detection of colorectal cancer in people aged 60-69 by what %?

A

11%

18
Q

what laboratory tests are required?

A

routine bloods - FBC + may show microcytic (iron-deficiency) anaemia, LFTS & clotting
tumour markers NOT USED

19
Q

why is the tumour marker Carcinoembryonic Antigen (CEA) not used as a test?

A

poor sensitivity and specificity

20
Q

what is Carcinoembryonic Antigen (CEA) used for?

A

monitoring disease progression - conducted pre and post treatment

21
Q

what is the gold standard for diagnosis of colorectal cancer?

A

colonoscopy with biopsy

22
Q

why might colonoscopy not be suitable for a patient?

A

frailty
co-morbidities
intolerance

23
Q

what is used in patients who cannot tolerate colonoscopy?

A

flexible sigmoidoscopy

CT colonography

24
Q

what investigations are required for staging once the diagnosis has been made?

A 
CT scan - chest abdo pelvis to look for distant metastases and local invasion full colonoscopy or CT colonogram is required to check for a 2nd (synchronous) tumour if not used initially)
MRI rectum (rectal cancers only)- depth and invasion and potential need fro pre-op chemotherapy 
endo-anal USS (T1 or T2 rectal caner) - asses suitability for trans-anal resection
25
Q

what staging is used for colorectal cancer?

A 
TNM system (like most cancers)
T = depth the tumour invades the bowel wall 
N = extent of spread to local lymph nodes
M = metastasis or not
Dukes staging used in some places
26
Q

what are the Dukes’ stages

A 
A  = Confined beneath the muscularis propria = 90% 5 year survival 
B  = Extension through the muscularis propria = 65% 5 year survival 
C = Involvement of regional lymph nodes = 30% 5 year survival 
D = distant metastasis = <10% 5 year survival
27
Q

what is the curative management of colon cancer?

A

surgery - suitable regional colectomy to ensure removal of the primary tumour with adequate margins and lymphatic drainage followed by primary anastomosis or formation of a stoma

28
Q

what is a right hemicolectomy or extended right hemicolectomy and when is it used?

A

caecal tumours or ascending colon tumours
extended option performed for any transverse colon tumours. During procedure the ileocolic, right colic, and right branch of the middle colic vessels (branches of the SMA) are divided and removed with their mesenteries.

29
Q

what is a left hemicolectomy and when is it used?

A

descending colon tumours Similar to the right hemicolectomy, the left branch of the middle colic vessels (branch of SMA/SMV), the inferior mesenteric vein, and the left colic vessels (branches of the IMA/IMV) are divided and removed with their mesenteries.

30
Q

what is a sigmoidcolectomy

A

sigmoid colon tumours. In this instance, the IMA is fully dissected out with the tumour in order to ensure adequate margins are obtained

31
Q

what is an anterior resection and when is it used?

A

high rectal tumours, typically if >5cm from anus.
This approach is favoured as leaves the rectal sphincter intact if an anastomosis is performed (unlike AP resections). Often a defunctioning loop ileostomy is performed - protects the anastomosis and reduces complications in the event of an anastomotic leak
can then be reversed electively in 4-6 months

32
Q

what is an abdominoperineal resection (AP) and when is it used?

A

low rectal tumours, typically <5cm from the anus. This technique involves excision of the distal colon, rectum and anal sphincters, resulting in a permanent colostomy

33
Q

What is Hartmann’s Procedure and when is it used?

A

emergency bowel surgery - in bowel obstruction of perforation
complete resection of the recto-sigmoid colon with the formation of an end colostomy and the closure of the rectal stump

34
Q

when is chemotherapy indicated?

A

patients with advanced disease

35
Q

what is an example of a chemotherapy regime for patients with metastatic colorectal cancer?

A 
FOLFOX
Folinic acid
Fluorouracil 
Oxaliplatin 
demonstrated to significantly improve 3 year disease free survival for patients with advanced colon cancer
36
Q

why is radiotherapy rarely used in colon cancer and when is it used?

A

risk of damage to the small bowel
used as neo-adjuvant treatment
used fro patients with rectal cancers which look on MRI to have threatened circumferential resection. underfo pre op long course chemo-radiation to shrink tumour - increases chance of complete resection and cure

37
Q

what is the focus of palliative care in colon cancer?

A

reducing cancer growth and ensuring adequate symptom control

38
Q

what are the palliative care options for patients with colon cancer?

A

endoluminal stenting - relieve acute bowel obstruction in patients with left-sided tumours
stoma formation - acute obstruction relief
resection of secondaries - can be done with adjuvant chemotherapy for any liver mets

General Surgery (5 decks)

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