Colorectal cancer Flashcards
What are the risk factors for sporadic cases of colorectal cancer?
Age
Male
Previous adenoma/colorectal cancer
Environmental influences- diet, obesity, lack of exercise, smoking, diabetes mellitus
What are the risk factors for colorectal cancer?
Familial risk
Inherited conditions
Underlying IBC
What do the majority of colorectal cancers arise from?
Existing colorectal polyps
What are colorectal polyps?
Protuberant growths with a variety of histological types, which can be epithelial or mesenchymal, benign or malignant
What are adenomas?
Benign, premalignant, epithelial growths which can develop to tumours
How do adenomas develop to tumours?
Activation of oncogenes
Loss of tumour suppressor genes
Defective DNA repair pathway genes
What are the main histological types of adenomas?
Tubular
Villous
What is the usual presentation of colorectal cancer?
Rectal bleeding
Altered bowel habits
Iron deficiency anaemia- in men and non menstruating women
Palpable rectal or lower right abide mass
Acute colonic obstruction
Weight loss, anorexia
What investigations are carried out for colorectal cancer?
Colonoscopy- gold standard
Imaging- barium enema, CT colonography
CT abdo/pelvis
What are the risks of colonoscopy?
Perforation
Bleeding
What are the benefits of a colonoscopy?
Diagnostic and therapeutic-
Biopsy can be taken
Polypectomy can be carried out
How is colorectal cancer staged?
CT
MRI for rectal tumours
PET or rectal endoscopic ultrasound
What classification systems are used for colorectal cancer?
TMN
Dukes
What is Dukes classification of colorectal cancer?
A= tumour confined to mucosa B= tumour extended through mucosa to muscle layer C= involvement of lymph nodes D= distant metastases
What are the treatment options for colorectal cancer?
Surgery
Chemo
Radiotherapy
How is Dukes A cancer treated?
Endoscopic or total resection
What does operative procedure depend on?
Site, size and stage of tumour
What surgical procedures can be used to treat colorectal cancer?
Tumour or bowel resection
Stoma formation
Removal of lymph nodes for histological analysis
Partial hepatectomy for metastases
How is chemotherapy used in colorectal cancer?
Advanced B cancer onwards
Adjuvant therapy
Clears any micrometastases
How is radiotherapy used in colorectal cancer?
Rectal cancer
Neoadjuvant therapy
Shrinks tumour before resection
What is the 5year survival of each of the Dukes classifications?
A 5 year survival 83%
B 5 year survival 64%
C 5 year survival 38%
D 5 year survival 3%
How is screening down in the general population?
5 yearly FOB test for 50-74 year olds
What is the aim of screening in the general population?
Detect premalignant carcinomas and early cancers
Who are high risk groups for colorectal cancer?
Heritable conditions IBD Familial risk Previous adenomas Previous colorectal cancer
What inheritable conditions can cause colorectal cancer?
Familial adenomatous polyposis
Hereditary non polyposis colorectal cancer
What does familial adenomatous polyposis cause?
Multiple adenomas throughout colon
Extracolonic manifestations
What is done for those with familial adenomatous polyposis?
Annual colonoscopy from age 10-12
Prophylactic protocolectomy at age 16-25
NSAIDs chen-prevention- reduces polyp number and prevents re-occurance of higher grade adenomas
What does hereditary non-polyposis cause?
Early onset right sided colorectal cancer
What is hereditary non-polyposis associated with?
Cancers in colorectal Endometrium Geritourinary Stomach Pancreas
What screening is done for those with hereditary non polyposis?
Colonoscopy every 2 years
What screening is done for those with IBD?
Colonoscopy 10 years after diagnosis then repeated at intervals depending on duration, extent and activity of inflammation
What screening is done for those with a high familial risk?
5 yearly colonoscopy from 50 years
What is done for those with a low familial risk?
Colonoscopy at 55
What screening is done for those with a history of colorectal cancer?
5 yearly colonoscopy
