Colorectal cancer

Question 1

Aetiology of colorectal cancer

Answer 1

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

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

Question 2

Risk factors for colorectal cancer

Answer 2

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

Question 3

Epidemiology of colorectal cancer

Answer 3

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

Question 4

Symptoms of colorectal cancer

Answer 4

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

Question 5

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

Answer 5

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

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

Question 6

Signs of colorectal cancer on examination

Answer 6

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)

Question 7

Investigations for colorectal cancer

Answer 7

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

Question 8

What staging is used for colorectal cancer

Answer 8

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

Question 9

Management for colorectal cancer

Answer 9

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)

Question 10

What is the screening programme for colorectal cancer

Answer 10

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

Question 11

Complications of treatment for colorectal cancer

Answer 11

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

Question 12

Prognosis for colorectal cancer

Answer 12

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

Common mets = liver, lung, bone, brain