7.6 Cancers of the Digestive System Flashcards
True or false: the mechanism of chronic liver disease is thought to be entirely separate from hepatocellular carcinoma
- False
- Most HCC arises on a background of chronic liver disease, and emerges with development of cirrhosis
List three classes of factors that are thought to predispose to HCC, and give examples
- Toxicity (alcohol, aflatoxin)
- Viral infection (Hep B/C)
- Metabolic disease (hereditary haemochromatosis, alpha 1 antitrypsin deficiency)
List three mutations that may cause Hepatocellular Carcinoma
- Activation of B-catenin
- Inactivation of p53
- Increase in IL-6
List three kinds of lesions that may act as precursors for HCC
- Hepatocellular adenoma
- Dysplastic nodules
- Diffuse cell changes
What are hepatocellular adenomas? Are they more common in men or women? What medication are they associated with?
- Benign lesions of the liver; arise in non-cirrhotic liver
- More common in women
- Associated w/ OCP
What are the two types of dysplastic nodules in the liver? Which is more likely to progress to HCC?
- High grade and low grade nodules
- High grade is more likely to progress
CRC is the _____ most common type of cancer in Australia. It is more common in men/women, and almost all are _______carcinomas
- Third most common
- More common in men
- Almost all are adenocarcinomas
Modifiable risk factors for CRC
- Smoking
- Obesity
- Processed meat
- Alcohol
- Low fibre, high refined carbs
List three protective factors for colorectal cancer
- Vegetarian diet
- High fibre diet
- NSAIDs
What is familial adenomatous polyposis (FAP)? What is its genetic nature? What is the prognosis?
- Genetically, it is autosomal dominant (caused by mutation in APC gene)
- Causes many adenomas of the colon, prophylactic colectomy indicated
Explain the pathophys of Lynch Syndrome. What is it also called?
- Mutation in mismatch repair, causing mutations in microsatellite DNA regions affecting areas of DNA that control cell replication
- Also called Hereditary Non-Polyposis Colorectal Cancer (HNPCC)
What is the genetic basis of HNPCC/Lynch Syndrome?
- Patients inherit one mutant gene (usually of MSH2 or MLH1
- These are mismatch repair genes (what’s the link to pathophysiology?)
- When the second copy is lost, cell growth becomes out of control
Familial Adenomatous Polyposis typifies which aetiological mechanism of CRC?
Adenoma-carcinoma progression
What is the most common mechanism of CRC pathogenesis?
Progression from adenomatous polyps
List some non-modifiable risk factors for colorectal cancer
- Family history (closer = worse)
- FAP/HNPCC
- IBD
- Increasing age
- African descent
General presentation symptoms for all crc
- Changes in bowel habit
- Unexpected weight loss
- Rectal bleeding
- Abdo pain
Common symptoms/signs for right sided crc
- Signs of anaemia (stealthy occult bleeding in proximal colon)
- Right sided abdo pain
- Ielocaecal valve obstruction (late)
Common symptoms/signs for left sided crc
- Rectal bleeding more common
- Rectal mucous
- Lower abdo colic
- Abdo distension (late)
CRC Ix
- Bloods: CBC, EUC, LFT, ?Carcinoembryonic Antigen test (after diagnosis)
- Foecal occult blood test (no point if bleeding)
- Colonoscopy
- Imaging (MRI/CT)
Why do we resect widely in surgical management of colorectal cancer?
- Tumours will drain in lymphovascular manner
- Need to perform lymphovascular clearance (by resecting) as well
What is one consideration if we want to ensure the colon anastomoses after CRC resection?
Must ensure adequate blood supply to prevent necrosis
True or false: due to improvement in surgical tech, stoma are almost never indicated in CRC patients nowadays
- False
- Stoma may be required; not exactly uncommon
Under what circumstances do we screen for a disease?
- Can be detected early
- Accepted treatment exists
- Can be done acceptably, inexpensively, and sensitively
