Case 21 - CRC, Infective Diarrhoea and Diverticular Disease Flashcards
What is CRC?
More prevalent in the developed world
Most common in the recto-sigmoid junction
Most are found when they are at a late stage
Pathophysiology of CRC?
Can have a polyp that can become cancerous
Ulcer that can become malignant
Mutations lead form polyp > adenoma > carcinoma
Average of 5y difference between adenoma found and CRC
What are the genetic predispositions to CRC?
FAP Familial adenomatous polyposis Mutation in APC allele When there is a predisposition to many polyps forming in the colon Some eventually will become malignant
p53
Regulates apoptosis in cells - if there is a mutation in this then the cell will not undergo apoptosis when malignant
TSG
HNPCC
Hereditary non-polyposis
When there is a mutation in the mis-match repair mechanism gene
This means that base pair errors will not be corrected, leading to a higher likelihood of mutation and therefore malignancy
Linked with other cancers in Lynch syndrome
K-RAS
Makes missense base pair change
Proto-oncogene
RFs for CRC?
Age IBD HNPCC FAP Obesity
Symptoms of CRC?
Red flags: Abdo/rectal mass Rectal bleeding Unexplained anaemia Unexplained Weight loss FHx Change in bowel habit >60y
Screening for CRC?
Done in everyone over 55y - one off colonoscopy
At 60y offered bowel cancer stool screening every 2 years, until 75y
Differentials for CRC?
Haemorrhoids
Proctitis
IBD
Anal fissure
Investigations for CRC?
Imaging:
- Colonscopy
- Barium enema
- CT/MR virtual colonscopy
- Staging CT/PET
Staging of CRC?
T1 = in the submucosa T2 = in the muscularis T3 = in the adventitia T4 = spread to other adventitia (T4a), perforation of the bowel (T4b)
M0-1
N0-2
Dukes staging of CRC?
A = T1N0M0, T2N0M0
B=T3N0M0, T4N0M0
C= Any N1 or 2
D=Any M1
Treatment for CRC
Surgical resection
Adjuvant chemotherapy
What is a hemicolectomy?
Removal of the R colon by surgery
Will try and leave 5cm healthy bowel either side of the resection margin
What is an anterior resection?
Removal of the L colon
Try and leave 5cm healthy bowel either side of the malignancy
May have to have a defunctioning loop ileostomy
Contrast enema X-ray determines if can be anastamosed
What is an abdominoperineal resection?
Removal of part of the colon and rectum, excision of the anus
Will have to have permanent colostomy
What is rectal surgery based on staging?
T1 = surgical resection through anus T2 = resection open T3 = radiotherapy and anterior resection T4 = Lt radiotherapy, assess need for surgery
