Colorectal cancer Flashcards
Colorectal carcinoma
95% adenocarcinomas
Most commonly rectal or sigmoidal
Risk factors for colorectal carcinoma
- Diet: ↓ fibre
- IBD
- Familial: FAP, HNPCC - FHx
- Smoking and alcohol
- Male
Presentation of colorectal carcinoma
Left: • Altered bowel habit • PR mass • Obstruction • Bleeding / mucus PR • Tenesmus
Right (late presentation)
• Anaemia and Wt. loss
• Abdominal pain
Both: • Abdominal mass • Perforation • Haemorrhage • Fistula
Examination of colorectal carcinoma
- Palpable mass: per abdomen or PR
- Perianal fistulae
- Hepatomegaly
- Anaemia
- Signs of obstruction
Investigations of colorectal carcinoma
• Bloods
- FBC: Hb
- LFTs: mets
- Tumour Marker: CEA
• Imaging
- CXR: lung mets
- USS liver: mets
- CT CAP - staging
- MRI (depth) - rectal cancers only
- Endoanal USS: staging early rectal tumours
§ Ba / gastrograffin enema: apple-core lesion
• Endoscopy + Biopsy - gold standard
- Flexi sigmoid
- Colonoscopy (right side)
MRI imaging in CRC
Best for rectal Ca and liver mets
What score is used to stage CRC
Dukes staging
Surgery for rectal carcinoma
• Neo-adjuvant radiotherapy - shrink size
• Anterior resection: tumour 4-5cm from anal verge
- Defunction with loop ileostomy
• Abdominal Perineal resection: <4cm from anal verge
• Total mesorectal excision for tumours of the
middle and lower third
Surgery of other tumours
- Sigmoid: high anterior resection or sigmoid colectomy
- Left: left hemicolectomy
- Transverse: extended right hemicolectomy
- Caecal / right: right hemicolectomy
CRC screening
- FIT Testing for 60-75yrs
- every 2yrs
- Colonoscopy if +ve
Familial Adenomatous Polyposis
- Autosomal dominant
- APC gene
- 100-1000s of adenomas which leads to CRC
Hereditary Non-Polyposis Colorectal Cancer
- Autosomal dominant
* Mutation of mismatch repair enzymes
Referral
- ≥40yrs with unexplained weight loss and abdominal pain
- ≥50yrs with unexplained rectal bleeding
- ≥60yrs with iron‑deficiency anaemia or change in bowel habit
- Positive occult blood screening test
Why is a Endo-anal ultrasound done
Assess suitability for trans-anal resection
Right Hemicolectomy
Surgical approach for caecal to ascending colon tumours
Ileocolic, right colic, and right branch of the middle colic vessels (branches of the SMA) are divided and removed with their mesenteries
Extended Right Hemicolectomy
Performed for distal colon tumours
Left Hemicolectomy
Descending colon tumours
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
Sigmoidcolectomy
Sigmoid colon tumours
IMA is fully dissected out
Anterior Resection
High rectal tumours typically >5cm from anus
- renal sphincter intact
Defunctioning loop ileostomy is performed
Abdominoperineal (AP) Resection
Low rectal tumours, typically <5cm from the anus
Excision of the distal colon, rectum and anal sphincters, resulting in a permanent colostomy
Hartmann’s Procedure
Emergency bowel surgery
- bowel obstruction
- perforation
Involves a complete resection of the recto-sigmoid colon
Formation of an end colostomy and the closure of the rectal stump
Colorectal cancer presenting with bowel obstruction
Can be relieved by either a decompressing colostomy or endoscopic stenting
Staging and mx after
Radiotherapy
Used in rectal cancer
Not given in colon cancer due to the risk of damage to the small bowel
Neo-adjuvant treatment
Can be given alongside chemotherapy.
In a pt with rectal bleeding what Hb level needs a transfusion of packed red blood cells
< 70
