Colorectal cancer Flashcards
Aetiology of colorectal cancer
90% adenocarcinoma
Rare types: carcinoid, GI stromal, lymphoma
71% arise in the colon and 29% in the rectum
Risk factors for colorectal cancer
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
Epidemiology of colorectal cancer
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
Symptoms of colorectal cancer
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
What is the difference in presentation between right and left sided colorectal cancer
Right: presents later, anaemia much more likely (90%), weight loss, malaise
Left: presents earlier with change in bowel habit, rectal bleeding, tenesmus
Signs of colorectal cancer on examination
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)
Investigations for colorectal cancer
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
What staging is used for colorectal cancer
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
Management for colorectal cancer
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)
What is the screening programme for colorectal cancer
- One off flexible sigmoidoscopy for all at 55yo
- Faecal immunochemical test (FIT)/Faecal occult blood test (FOBT) every 2 years for all 60-74
Anything +ve → colonoscopy
Complications of treatment for colorectal cancer
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
Prognosis for colorectal cancer
CRC: 5 year survival approx. 60%
Anal cancer: 60%
Common mets = liver, lung, bone, brain