Lower GI Neoplasia Flashcards
How many sections make up the large bowel?
5: Ascending colon transverse colon descending colon sigmoid colon rectum
Where do most cases of lower GI neoplasias occur and why?
On the left in the sigmoid colon and rctum because this is where food (and carcinogens) sit
What is a colorectal carcinoma?
Cancer in the colon or rectum
What are the risks associated with colorectal cancer?
Aged 60 yrs + Family history Weight Diet Alcohol
What are the two types of colorectal cancer?
HNPCC (hereditary non polyposis colorectal cancer)
FAP (familial adenomatous polyposis)
What is HNPCC?
Hereditary non polyposis colorectal cancer
The healthy form of this gene helps DNA repair itself. If you have the gene you’re at higher risk- poor DNA repair
90% M. 70% F with gene get bowel cancer by age 70
What are the risks for HNPCC?
Ashkenazijews
Benign polyps in bowel
What is FAP?
Familial adenomatous polyposis Causes small non cancerous growths (benign poylps) to develop in the large bowel. Some can develop to cancer Surgery by age 25 to remove colon Epidermoid cysts are common Subtype is Gardners syndrome
What is Gardners syndrome?
Subtype of FAP
Mutation in APC gene, sebaceous cysts, dermoid cysts, fibromas, desmoid tumours, osteomas - bony growths on the jaw
What are the three causes of polyps?
Metaplastic - localised hyperplastic proliferation
Neoplastic - atypical epithelial proliferation
Harmatoma - formed from elements of lamina propria
How does an adenoma - carcinoma sequence progress?
Benign - acquire dysplasia - carcinoma in situ - invasive disease
What is dysplasia?
Abnormalities in maturation of epithelial cells (premalignant)
What is malignancy?
Invasion into soft tissue - process can metastasize to lymph/ distant sites
What is the link with ulcerative colitis and crohn’s disease to bowel cancer?
Higher risk of bowel cancer due to damage in the bowel lining and need to always repair itself so their is high cell turnover
How does diet impact bowel cancer?
High fibre diet lowers the risk of poylps and cancer
Red/ processed meat increases the risk
Alcohol, weight and exercise increase irsk
