colorectal cancer

Question 1

commonest location of colorectal cancers

Answer 1

rectal - 40%
sigmoid - 30%

descending colon - 5%
transverse colon - 10%

ascending colon + caecum - 15%

Question 2

genetic causes of colorectal cancer

Answer 2

hereditary non-polyposis colorectal carcinoma (HNPCC) 5%

familial adenomatous polyposis (FAP) <1%

Question 3

hereditary non-polyposis colorectal carcinoma - HNPCC (lynch syndrome)

Answer 3

autosomal dominant
commonest form of inherited colon cancer

commonest genes involved = MSH2, MLH1

amsterdam criteria used to aid diagnosis

Question 4

what other cancer are patients with HNPCC at risk of

Answer 4

endometrial cancer

Question 5

familial adenomatous polyposis (FAP)

Answer 5

rare autosomal dominant
- hundreds of polyps by age 30-40yrs

Question 6

which procedure do patients with familial adenomatous polyposis (FAP) commonly have done

Answer 6

total proctocolectomy with ileal pouch anal anastomosis (IPAA)

-> in their twentites

Question 7

helpful tumour marker for colorectal cancer

Answer 7

carcinoembryonic antigen (CEA)

Question 8

mx of colorectal cancer in caecal, ascending or proximal tranverse colon

Answer 8

right hemiolectomy

• ileo-colic anastamosis

Question 9

mx of colorectal cancer in upper rectum

Answer 9

anterior resection (TME)

• colo-rectal anastomosis

Question 10

mx of colorectal cancer in sigmoid colon

Answer 10

high anterior resection

Question 11

mx of colorectal cancer in anal verge

Answer 11

adomino-perineal excision of rectum

Question 12

emergency surgery where bowel has perforated mx

Answer 12

Hartmann’s (resection of sigmoid + end colostomy)

• do end colostomy - safer, can be reversed later
• risk of anastomosis is much greater

Question 13

colorectal cancer screening

Answer 13

FIT test every 2 years for 60-74 in england, and 50-74 in scotland

• faecal occult blood, antibodies that specificall recognise human haemoglobin