Development of Neoplasia in the GI Tract Flashcards
What are some of the clinical clues that someone may develop colorectal cancer?
- Colon cancer usually develop from benign polyps.
Explain the relevance of genetics in colorectal cancer.
5% have a known familial syndrome
- Familial adenomatous polyposis (FAP),
- Hereditary non polyposis colorectal cancer (HNPCC)
Another 5-20% have a genetic contribution
Outline familial adenomatous polyposis syndrome:
Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition in which numerous adenomatous polyps form mainly in the epithelium of the large intestine. While these polyps start out benign, malignant transformation into colon cancer occurs when they are left untreated.
FAP is associated with a mutation in what gene?
Apc gene
What is Hereditary non-polyposis colorectal cancer?
Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary colorectal cancer. It is inherited as an autosomal dominant syndrome as a result of defective mismatch repair (MMR) proteins.
H.pylori infection can lead to what different conditions?
Gastritis
Ulcer
Gastric cancer
MALT lymphoma
Summarise of H.pylori infection leads gastric cancer?
H. pylori infection causes chronic gastritis, which eventually leads to atrophic gastritis and pre-malignant intestinal metaplasia.
What is meant by a loss of heterozygosity?
Loss of heterozygosity (LOH) is a cross chromosomal event that results in loss of the entire gene and the surrounding chromosomal region.
What are the two major types of gastric cancer?
Intestinal Type 1
Diffuse Type 2
Explain Intestinal Type 1 gastric cancer.
Intestinal ( type 1 ) with well-formed glandular structures (differentiated). The tumours are polypoid or ulcerating lesions with heaped-up, rolled edges. Intestinal metaplasia is seen in the surrounding mucosa, often with H. pylori . This type is more likely to involve the distal stomach and occur in patients with atrophic gastritis. It has a strong environmental association.
Explain diffuse Type 2 gastric cancer.
Diffuse ( type 2 ) with poorly cohesive cells (undifferentiated) that tend to infiltrate the gastric wall. It may involve any part of the stomach, especially the cardia, and has a worse prognosis than the intestinal type.
What are the clinical signs of upper GI bleeding?
The cardinal features are haematemesis (the vomiting of blood) and melaena (the passage of black tarry stools).
What is the most common cause of gastrointestinal bleeding.
Peptic ulceration is the most common cause of serious and life-threatening gastrointestinal bleeding.
Lynch syndrome aka
HNPCC
What is meant by the adenoma-carcinoma sequence?
The adenoma-carcinoma sequence refers to a stepwise pattern of mutational activation of oncogenes (e.g. K-ras) and inactivation of tumour suppressor genes (e.g. p53) that results in cancer.
