Colorectal cancer Flashcards

1
Q

Aetiology of colorectal cancer

A

90% adenocarcinoma
Rare types: carcinoid, GI stromal, lymphoma

71% arise in the colon and 29% in the rectum

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2
Q

Risk factors for colorectal cancer

A

Increasing age (90% >40yo)
Genetic syndromes e.g. FAP, HnPCC, MAP, PJS, JP)
IBD (Specifically UC)
Obesity
Smoking
Alcohol consumption
Acromegaly, limited physical activity, lack of dietary fibre

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3
Q

Epidemiology of colorectal cancer

A

Third most common cause of cancer death
Third most common cancer
Lifetime risk is 4.4% in men and 4% in women (1 in 20)
Incidence and mortality lower in Hispanic/Asians compared to white/black

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4
Q

Symptoms of colorectal cancer

A

Change in bowel habit e.g. increased frequency, looser stools
Rectal bleeding (mixed in)
Abdominal pain
Weight loss
Loss of appetite
Anaemia → fatigue, SOB
DVT
ABdominal lump or distension

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5
Q

What is the difference in presentation between right and left sided colorectal cancer

A

Right: presents later, anaemia much more likely (90%), weight loss, malaise

Left: presents earlier with change in bowel habit, rectal bleeding, tenesmus

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6
Q

Signs of colorectal cancer on examination

A

Inspection
- Anaemia: conjunctival pallor (R-sided)
- Palpable lymph nodes (late)
Abdo
- Abdominal mass (late)
- Abdominal distensions (late)
- Metastases: shifting dullness, hepatomegaly
DRE
- Rectal mass on DRE (L-sided)

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7
Q

Investigations for colorectal cancer

A

Consider referral

Unexplained weight loss/loss of appetite/DVT/anal mass/occult blood/rectal mass → 2ww
IDA, non-IDA >60yo, change in bowel habit → FIT

faecal immunochemical testing (FIT): >10 mcg Hb/g → 2WW

FBC: ?anaemia
LFTs: normal
Renal: may be deranged if compression
CEA: raised (40%, non-specific)

Sigmoidoscopy/colonoscopy + biopsy
Barium enema (double contrast): colonic mass lesion, apple core lesion
CT colonography: if colonoscopy not possible, cannot obtain biopsy
CT CAP: ?Mets
Pelvic MRI

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8
Q

What staging is used for colorectal cancer

A

Previously: Duke’s

A: Tumour confined to the mucosa
Nodes -ve
95% 5ys

B1: Tumour growth into the muscularis proposa
Nodes -ve
80%

B2: Tumour growth through the muscularis proposa and serosa
Nodes -ve
80%

C1: Tumour spread to 1-4 regional lymph nodes
Apical +ve
65%

C2: Tumour spread to >4 regional lymph nodes
Apical +ve
65%

D: Distant metastases (liver, lung, bone)
5% (20% if resectable)

Now uses TNM staging
T1: invades innermost layer
T2: Muscle layer invasion
T3: outer lining invasion
T4: invades outside of the bowel wall

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9
Q

Management for colorectal cancer

A

Dependent on site of lesion/stage/grade etc.

For surgery → resection
Sigmoid colectomy + remove entire IMA
- Stage 1-3: post-op chemo
- Stage 4: pre-op chemo (neoadjuvant)

Not for surgery:
- Chemo (FOLFOX/FLOX)
- VEGF-i/EGFR-i
- Stenting of sigmoid/rectum
- Immunotherapy e.g. pembrolizumab (checkpoint inhibitor)

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10
Q

What is the screening programme for colorectal cancer

A
  1. One off flexible sigmoidoscopy for all at 55yo
  2. Faecal immunochemical test (FIT)/Faecal occult blood test (FOBT) every 2 years for all 60-74

Anything +ve → colonoscopy

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11
Q

Complications of treatment for colorectal cancer

A

Post-operative complications:
- Ileus: peristalsis halted → fluids stop moving in intestine → electrolytes diffuse into lumen → low electrolytes in blood and dehydrated picture DESPITE positive fluid balance; mx: NG + IV fluids
- Anastomotic dehiscence: 10% of colorectal anastomoses (“day 6, fever, septic picture)
- Low anterior resection syndrome
- Bladder dysfunction, erectile dysfunction

Chemo: bone marrow suppression, hepatotoxicity, gastrointestinal toxicity, alopecia, neuropathy, pulmonary fibrosis

Radiotherapy: faecal incontinence

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12
Q

Prognosis for colorectal cancer

A

CRC: 5 year survival approx. 60%
Anal cancer: 60%

Common mets = liver, lung, bone, brain

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