Colorectal Cancer Flashcards
What are the majority of colorectal cancers?
95% adenocarcinomas
What is the distribution of colorectal carcinomas?
2/3 colonic
1/3 rectal
What are the predisposing factors to colorectal carcinoma?
Neoplastic polyps
IBD
Genetic predisposition
Diet
Alcohol intake
Smoking
Previous cancer
What are polyps?
Growths that appear above the mucosa and can be inflammatory, hamartomatous or neoplastic.
Left in situ, polyps carry a risk of malignant transformation
What is the presentation of colorectal carcinoma?
Rectal bleeding
Altered bowel habits
Colonic obstruction
Tenesmus
Palpable mass
Weight loss
Anaemia
Abdominal pain
What are the tests for colonic cancer?
Bloods: FBC, FOBT, LFT
Sigmoidoscopy/Colonoscopy
MRI/CT
What are the 2 methods of staging colorectal cancer?
Dukes Criteria
TNM staging
What is Dukes A?
Confined to submucosa
What is Dukes B?
Invasion through muscularis mucosae without lymph node involvement
What is Dukes C?
Invasion of regional lymph nodes
What is Dukes D?
Presence of distant metastases?
What is the Tumour part of staging?
Tx- tumour can’t be assessed
Tis- in situ
T1- submucosa
T2- muscularis propria
T3- Serosa
T4- Invasion of adjacent structures
What is the Nodal part of staging?
N0- no node spread
N1- metastases in 1-3 regional nodes
N2- metastases in >3 regional nodes
What are the surgical treatments of CRC?
Right hemicolectomy
Left hemicolectomy
Sigmoid colectomy
Anterior resection
Abdomino-perineal resection
What is right hemicolectomy done for?
Caecal tumours
Ascending colon tumours
Proximal transverse colon tumours
What is left hemicolectomy done for?
Distal transverse colon tumours
Descending colon tumours
What is sigmoid colectomy?
Sigmoid tumours
What is anterior resection done for?
Low sigmoid tumours
High rectal tumours
What is abdomino- perineal resection done?
Low rectal tumours
When is endoscopic stenting used in CRC?
Palliation in malignant obstruction
Bridge to surgery in acute obstruction
Describe an ileostomy stoma
Right iliac fossa
Liquid, looser stools
Spouted
Describe a colostomy stoma
Left iliac fossa
Solid stools
No spout
When is radiotherapy used in CRC?
Palliation
Pre-op in rectal cancer
When is chemotherapy used in CRC?
Adjuvant
Palliation of metastatic disease
What tests are involved in population screening for CRC?
FOBT
qFIT
Flexible sigmoidoscopy
Colonoscopy
What is FOBT?
Faecal occult blood test (FOBT)
uses a chemical indicator that shows a colour change in the presence of blood in the stool
What is qFIT?
Quantitative Faecal Immunochemical Test (FIT)
Uses antibodies directed against human haemoglobin to detect blood in the stool
What groups are at high risk of CRC?
Heritable conditions
IBD
Familial risk
Previous adenocarcinoma
Previous Colorectal cancer
What are the genetic conditions associated with CRC?
HNPCC (Lynch syndrome)
FAP
MAP
Peutz- Jeghers syndrome
What is HNPCC?
Hereditary non-polyposis colorectal cancer
Autosomal dominant
Due to mutations in mismatch repair genes
1-3% of CRC
What is FAP?
Familial adenomatous polyposis
Autosomal dominant
Due to mutations in APC tumour suppressor gene
Causes multiple colorectal adenomas (>100) which undergo malignant transformation
What is MAP?
MUTYH- associated polyposis
Autosomal recessive
Due to variants in MUTYH base excision repair gene
What is Peutz- Jeghers syndrome?
Hamartomatous polyps
