Colorectal cancer

Question 1

Most common locations of colorectal cancer

Answer 1

40% rectal
30% sigmoid colon
15% ascending and caecum
10% transverse 
5% descending

Question 2

CRC screening

Answer 2

Faecal immunochemical test, FIT test every 2 years for 60-74 year olds.

Abnormal result -> colonoscopy.
5/10- normal
4/10- premalignant polyps which can be removed
1/10- cancer

New program for one off flexible sigmoidoscopy for 55 year olds.

Question 3

CRC referral guidelines

Answer 3

USC:
> 40 with weight loss and pain
> 50 with bleeding
> 60 with anaemia or a change in bowel habit.
Rectal or abdominal mass.

Question 4

Genetic conditions causing CRC- HNPCC

Answer 4

5% due to Lynch syndrome, HNPCC. Autosomal dominant condition, 90% develop cancers, highly aggressive. Also at risk of endometrial cancer.

Amsterdam criteria- 3 family CRC, spanning 2 generations, 1 < 50 yrs.

Question 5

Genetic conditions causing CRC- FAP

Answer 5

1% due to familial adenomatous polyposis. Mutation in APC gene. Autosomal dominant condition, hundreds of polyps. Usually have total colectomy and ileoanal pouch formation in 20s. Still at increased risk of duodenal tumours.

Variation- Gardner’s syndrome also causes osteomas of skull and mandible, thyroid carcinomas and epidermoid skin cysts.

Question 6

Treatment

Answer 6

Surgical resection. End stoma may be safer than anastomoses if surrounding sepsis, unstable patient, inexperienced surgeons.
Anastomoses need adequate blood supply, mucosal apposition and no tissue tension.

Obstructing lesion- stent or resection.

Adjuvant chemotherapy.

Rectal cancer- radiotherapy prior to resection surgery.

Question 7

CRC surgeries - 5

Answer 7

Right hemicolectomy- remove cancer in the caecum, ascending and transverse colon. Form ileocolic anastomosis.

Left hemicolectomy- for cancer in the distal transverse or descending colon. Form colo-colon anastomosis.

High anterior resection- for cancer in sigmoid colon, colo-rectal anastomosis.

Anterior resection- upper rectal and lower rectal cancers. Colo-rectal +/- refunctioning stoma.

Hartmann’s procedure- emergency setting for perforation. Risk of anastomosis too high. Resection of sigmoid colon and end colostomy formed