GI Cancers Flashcards
Describe types of oesophageal cancer
Squamous cell carcinoma - upper 2/3. From normal oesophageal squamous epithelium. Goes through acetaldehyde pathway (ethanol broken down by alcohol dehydrogenase into oxidised acetaldehyde and then oxidised to acetate by acetaldehyde dehydrogenase). More common in less developed world.
Adenocarcinoma - lower 1/3. Related to acid reflux and develops from metaplastic epithelium. More common in more developed world.
Describe progression from reflux to cancer
Oesophagitis (inflammation - GORD). Barrett’s (metaplasia). Oesophageal cancer (neoplasia).
Describe progression from Barretts to cancer
Barrett’s leads to low grade dysplasia, then high grade, then adenocarninoma. Surveillance guidelines are:
No dysplasia → Every 2-3 years
LGD → every 6 months
HGD → intervention
Who does oesophageal cancer mainly affect?
Elderly, more males than females (adenocarcinoma), late presentation includes weight loss and dysphagia, management pathway (endoscopy and biopsy to diagnose, laparoscopy and CT to stage, surgery to cure)
How is an oesophagectomy carried out?
Using Ivor Lewis approach. Esophageal tumor is removed through an abdominal incision and a right thoracotomy (a surgical incision of the chest wall)
Who does colorectal cancer affect?
More men than women, people over 50, most common GI cancer in western society
What are forms of colorectal cancer?
Sporadic - no Fx, isolated lesion, older person
Familial - has family history, closer relative and younger family diagnosis means more risk
Hereditary - specific gene defect. Familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome)
Describe colorectal cancer development
Normal becomes hyperproliferative epithelium then small adenoma, large adenoma and finally carcinoma.
What are risk factors for colorectal cancer?
Past history - adenocarcinoma, ulcerative colitis
Family history - first degree relative below 55, relatives with genetic predisposition
Smoking, obesity, socioeconomic status
What is clinical presentation of caecal and right sided colon cancer?
Iron deficiency anaemia (most common) Change of bowel habit (diarrhoea) Distal ileum obstruction (late) Palpable mass (late)
What is clinical presentation of left sided and sigmoid carcinoma?
PR bleeding, mucus Thin stool (late)
What is clinical presentation of rectal carcinoma?
PR bleeding, mucus
Tenesmus
Anal, perineal, sacral pain (late)
What are late clinical signs of a metastases?
Liver (hepatic pain, jaundice) Lung (cough) Regional lymph nodes Peritoneum Sister Mary Joseph nodule
What are signs of primary cancer?
Abdominal mass
DRE: most <12cm dentate and reached by examining finger
Rigid sigmoidoscopy
Abdominal tenderness and distension – large bowel obstruction
What are signs of metastasis and complications?
Hepatomegaly (mets)
Monophonic wheeze
Bone pain
What faecal occult blood tests conducted to investigate colon cancer?
Guaiac test – based on pseudoperoxidase activity of haematin. Sensitivity of 40-80%; Specificity of 98%.
Dietary restrictions – avoid red meat, melons, horse-radish, vitamin C & NSAIDs for 3 days before test
FIT (Faecal Immunochemical Test) - detects minute amounts of blood in faeces (faecal occult blood).
What blood tests conducted to investigate colon cancer?
FBC: anaemia, haematinics – low ferritin
Tumour markers: CEA which is useful for monitoring
What are the uses of colonoscopy?
Can visualize lesions < 5mm
Small polyps can be removed
Reduced cancer incidence - Usually performed under sedation
What are the uses of CT colonoscopy?
Can visualize lesions > 5mm
No need for sedation
Less invasive, better tolerated
If lesions identified patient needs colonoscopy for diagnosis
What does MRI of pelvis for rectal cancer reveal?
Depth of invasion, mesorectal lymph node involvement
No bowel prep or sedation required
Help choose between preoperative chemoradiotherapy or straight to surgery
How is obstructive colon carcinoma treated surgically?
Right & transverse colon – resection and primary anastomosis
Left sided obstruction
1. Hartmann’s procedure - Proximal end colostomy (LIF)
+/- Reversal in 6 months
2. Primary anastomosis - Intraoperative bowel lavage with primary anastomosis (10% leak)
3. Defunctioning ileostomy
4. Palliative stent
Describe epidemiology of pancreatic ductal carcinoma
80-90% present late. 15-20% have resectable disease. Mainly in 60-80 year olds. More men than women.
What are risk factors for pancreatic cancer?
Chronic pancreatitis, Type 2 diabetes, cigarette smoking, family history
Describe pancreatic cancer pathogenesis
Pancreatic intraepithelial neoplasias. PDAs evolve through non-invasive neoplastic precursor lesions
PanINs are microscopic (<5 mm diameter) & not visible by pancreatic imaging
Acquire clonally selected genetic & epigenetic alterations along the way
Describe clinical presentation of head of pancreas cancer
Jaundice Palpable gallbladder Weight loss Pain (epigastric) Gastrointestinal bleeding
Describe clinical presentation of carcinoma of the body & tail of pancreas
Insidious + asymptomatic in early stages
Marked weight loss with back pain
Vomiting at late stage due to invasion at duodenojejunal flexure
Most unresectable by diagnosis
What investigations done for pancreatic cancer?
- Tumour marker CA19-9 - falsely elevated in pancreatitis, hepatic dysfunction and obstructive jaundice. >200 U/mL has high sensitivity and in thousands is very specific.
- Ultrasonography - can identify pancreatic tumour. dilated bile duct and liver metastases.
- Dual phase CT - predicts resectability.
- MRI imaging detects and predicts resectability with accuracies similar to CT
- MRCP provides ductal images without complications of ERCP
How does ERCP help in pancreatic cancer?
confirms the typical ‘double duct’ sign
aspiration/brushing of the bile-duct system
therapeutic modality → biliary stenting to relieve jaundice
Describe primary liver cancer (hepatocellular carcinoma)
Aetiology: Underlying cirrhosis, aflatoxin exposure
Surgical excision with curative intent. Median survival without surgery is 4-6 months. 5 year survival above 30% post surgery.
Describe gallbladder cancer
Aetiology unknown. Median survival: 5-8 months. Surgical excision with curative intent.
