Colorectal Cancer Flashcards
The majority of colorectal cancers are what?
Adenocarcinoma (95%)
What are the risk factors for sporadic colorectal cancer?
Advanced age
Male
Previous adenoma/CRC
Environmental
What are the environmental risk factors for CRC?
Diet (low fibre, calc, high red meat) Alcohol Obesity Low exercise Smoking DM
What are colorectal adenomas?
Colorectal polyps, usually benign
Tubular or villous
What factors make colorectal adenomas high risk?
Size
Number
Degree of dysplasia
Villous architecture
What actions cause an adenoma to become a carcinoma?
Activation of oncogenes
Loss of tumour suppressor genes
Defective DNA repair pathway
What oncogenes are involved in adenocarcinoma formation?
k-ras
c-myc
What tumour suppressor genes are involved in adenocarcinoma formation?
APC
p53
DCC
How does colorectal cancer present?
Rectal bleeding Altered bowel habit Iron deficiency anaemia Palpable rectal/low right mass Acute colonic obstruction Systemic symptoms
What investigations would you give for a patient with suspected colorectal cancer?
Colonoscopy (therapeutic too)
CT abdo - barium enema
How is colorectal cancer staged?
CT scan
MRI
PET/EUS
When is MRI used for staging of a colorectal tumour?
Rectal tumours
What criteria is used for staging colorectal cancer?
TNM
Duke’s
What is Duke’s A criteria?
Confined to submucosa
What is Duke’s B criteria?
Invasion through muscularis without lymphatic involvement
What is Duke’s C criteria?
Invasion through muscularis with regional lymph node involvement
What is Duke’s D criteria?
Presence of distant metastases
How does the T staging work for colorectal cancer
T1 - confined to submucosa
T2 - Confined to muscularis
T3 - confined to serosa
T4 - breached serosa
How does the N staging work for colorectal cancer
N0 - no nodes involved
N1 - Up to 3 regional nodes
N2 - 4+ nodes
How are most colorectal cancers treated?
Surgery
When is colorectal cancer treated endoscopically?
Dukes A
Cancerous polyps
How is chemotherapy used for colorectal cancer?
Dukes C, B
Adjuvant therapy
Micrometastases