Colorectal Cancer Flashcards
What are the principles of surgery in cancer?
To remove the cancer completely without damage to surrounding structures, have to remove the lymph nodes which drain the cancer and so the arteries must be removed so end up taking away more bowel than where the tumour is.
What is colorectal cancer?
Occurrence of malignant lesions in the mucosa of the colon and rectum. They are adenocarcinomas.
What is the aetiology/ pathology of colorectal cancer?
Mainly polyps but also: diet, family history, IBD, previous cancer, obesity, smoking, alcohol
What are polyps?
They are macroscopic protuberant growth from the mucosa. They can be pedunculated or sessile.
They are mainly adenomas – benign epithelial tumour of cells derived from glandular epithelium. They are all dysplastic and have dysregulated proliferation. They fail to fully differentiate and are all premalignant.
What is the evidence for adenoma carcinoma sequence?
Distribution of polyps matches cancer and background polyps in cancer.
Carcinomas found in adenomas
Coexistence in high risk groups
Follow up of patients declining polypectomy
What are the modes of spread of colorectal cancer?
Direct – invades other structures,
Lymphatic – critical, run with the blood vessels and are a critical aspect of surgery
Haematogenous – portal vein to the liver
Transcoelomic – spread through the peritoneal cavity. Classically to ovaries.
Implantation – structure line, wound, laparoscoptic ports sites
What are genetic syndromes of colorectal cancer?
HNPCC and FAP
Important inherited bowel cancer syndromes
Associated with other cancers
Screening of patient and family
What is HNPCC?
Slight distinction between them in terms of MMR status.
Inherited colon cancer.
A germline mutation in mismatch repair gene which is a tumour suppressor gene which corrects wrong base pairing. Leads to microsatellite instability and DNA repeats.
What is FAP?
APC mutation in 5q – beta catenin and wnt pathways.
Autosomal dominant inheritance.
Multiple extra intestinal manifestations
Originally defined by the presence of >100 colorectal adenomas.
What are the symptoms of colorectal cancer?
Originally defined by the presence of >100 colorectal adenomas.
Anorexia
Weight loss
Anaemia
Fatigue
What is endoscopy?
Colonoscopy, flexible fiber optic tubes.
Can biopsy and treat
what are the risks of colorectal cancer surgery?
Bleeding
Infection
Stoma
Death
What is oncogenetics?
The mapping of body compartments established during early embryologic development.
Ontogenetic theory of local tumour spread claims that local dissemination is facilitated in the ontogenetic compartment of origin, but suppressed at is borders in the early stages of cancer development.
What is adjuvant chemotherapy in colorectal cancer?
Designed to reduce the risk of developing mestases
Given to Dukes C patients
Usually 5FU based for 3 to 6 months
Works on DNA, but has toxicity problems
What are common chemotherapeutic drugs?
5FU – interferes with RNA synthesis and DNA replication
Leucovorin – potentiates 5FU
Oxaliplatin – cross links DNA, inhibiting synthesis
Irinotecan – topoisomerase inhibitor
Becacizumab – VEGF inhibitor
Cetuximab – EGFR inhibitor only for Ras wild type
