Large Bowel

Question 1

Colorectal cancer

Answer 1

Causes - idiopathic, adenomatous polyposis coli gene, hereditary non-polyposis colorectal cancer
RF - >60, FHx, IBD, low fibre diet
Change in bowel habit, rectal bleeding, weight loss (usually only if there are metastases), abdominal pain, and iron-deficiency anaemia
Right sided - abdominal pain, occult bleeding, or mass in RIF
Left sided - rectal bleeding, change in bowel habit or tenesmus, or mass in LIF/mass on PR exam
Ix - FBC (microcytic anaemia), U&E, LFTs, coagulation screen, CEA (for disease progression not diagnostic), CT CAP
Mx - MDT, surgery (curative), chemotherapy (pts with metastases), radiotherapy (rectal cancer)

Question 2

Dukes staging

Answer 2

A - confined beneath muscularis mucosa (5 year survival 90%)
B - extension through muscularis mucosa (5 year survival 65%)
C - involvement of regional lymph nodes (5 year survival 30%)
D - distant metastases (5 year survival <10%)

Question 3

Surgical options for colorectal cancer

Answer 3

Right hemicolectomy - for caecal or ascending colon tumours; during the procedure the 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 - for any transverse colon cancers
Left hemicolectomy - for descending colon tumours; 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
Sigmoidcolectomy - for sigmoid colon tumours; the IMA is fully dissected out with the tumour in order to ensure adequate margins are obtained
Anterior resection - for high rectal tumours (>5cm from the anus); favoured in rectal carcinoma as it leaves the rectal sphincter intact and functioning if anastamosis performed, unlike AP resections; a defunctioning loop ileostomy is performed to protect the anastomosis and reduce complications in the event of an anastomotic leak which is then reversed electively about four to six months later
Abdominoperineal (AP) resection - for low rectal tumours (<5cm from the anus); excision of the distal colon, rectum and anal sphincters, resulting in a permanent colostomy
Hartmann’s procedure - used in emergency bowel surgery (bowel obstruction/perforation); complete resection of the recto-sigmoid colon with the formation of an end-colostomy and the closure of the rectal stump