Gastric CA - a story of two diseases Flashcards
What are risk factors for gastric CA?
Risk factors
• H Pylori
• Previous gastric surgery
• Pernicious Anemia/ Adenamatous polyps – hypochloremic state
• Chronic atrophic gastritis – predisposes to metaplasia
• Radiation exposure
Features of early GC
Early is confined to the mucosa without lymph node spread.
• Type 1 – polyp no sub mucosal involvement
• Type 2a, 2b, 2c- elvevated, flat, depressed respectively
• Type 3 Excavated /ulcerated
Features of late GC - Borrman classification
Late/Advanced has progressed beyond the mucosa
Type 1 Fungating
Type 2 Ulcerated - raised everted edges with a necrotic base and surrounding mucosal infiltration
Type 3 Ulceratioon with inf
Type 4 infiltration - no lesion- wall of the stomach is invaded by malignancy and this causes a desmotic reaction where the stomah becomes contracted, shortened and hypoperistaltic, lining is plastica type aka leather bottle
Mechanisms of spread?
Direct - through stomach wall, to adjacent organs eg posteriorly may spread to pancreas, from pyloric region distal spread into the duodenum, and proximally in GE junction /esophagus
Lymphatic - lymphatic spread is along named vessels D1 spread - along the epiploic greater/lesser curve D2 is along the right and left gastric short gastric and right and left gastroepiploic
D3 - preaortic group of nodes - celiac
D4 - paraaortic nodes
Hematogenous - by venous emboli usually through the portal system - usually goes to the liver or lung
Transcelomic - spreads through and into the peritoneal cavity. cells break off and implant onto the peritoneal cavity causeing ascites - or spreads onto a fertile ovary and gives mucinous ovarian tumor (krukenburg tumors)
Presentation of gastric cancer
early gastric are asymptomatic
late gastric presents with indigestion nausea/vomiting postprandial fullness loss of appetite melena hematemesis weight loss dysphagia
Physical signs of GC
- Dehydrated
- cachexic and starved
- ascites
- pleural or peritoneal effusion
- jaundice due to liver involvement due to obstruction of hepatic bile duct
- gastric outlet obstruction
- peristaltic waves of the stomach
- succusion splash - when you shake them around its like youre shaking water in a bottle due to retained fluid in the stomach
what electrolyte derangements does pyloric outlet obstruction syndrome cause
when the pyloric outlet is blocked the vomiting which occurs is with a closed pylorus - this vomiting is usually non bilious
gastric juice contains sodium pottasium choride
Hypomatremia, hypochloremia, hypokalemia occurs and body becomes alkalotic and a metabolic alkalosis occurs
Paradoxical aciduria occurs even though the body is alkalotic. This happens because you have lost so much sodium that the kidney is holding on ot all the sodium in the body it can . it does this by exchanging with intracellular pottasium which you pass out in urine, as you get more and more hypokalemic the body can no longer put out pottassium so it puts out hydrogen ions and thats why urine is acidic
What blood investigations are done in advanced GC
- CBC - anemia
- Electrolytes - especially in outlet obstruction syndrome
- Liver Function tests - secondary mets or jaundice
- Tumor markers CEA, CA 19-9 any genetic predispositions and for follow up of the patient later on
What imaging is done in GC?
- Upper GI endoscopy - GOLD STANDARD
- Chest Radiograph - looking for pleural effusions
- Double contrast GI series
- CT MRI
- Endoscopic ultrasound - ultrasound stomach wall from inside the stomach especially in early cancer detection this is especially important as you can see all layers of the stomach and nodes. It also helps determine spread to nodes and adjacent organs.
normally do upperGI endoscopy with endoscopic ultrasound and CT/MRI
Huge J shaped stomach with retention of barium
Indicative of outlet obstruction syndrome
What is perioperative preparation for GC?
- Correction of electrolytes - rehydrate with IV fluid FIRST - N/S - hold off on K replacement initially until they are passing enough urine as if you don’t you can cause a hyperkalemia and kill them. After they are passing enough urine you can correct K.
Pottasium correction 40-60 meq per day in 70kg person - may need up to 100.
- Transfusion
- Cardiopulmonary assessment and optimization
- Pass nasogastric tube
- Stomach lavage - if vomiting wash stomach out with saline as you need a fairly clean stomach to perform the surgery on. we don’t want to spill the stomach contents into the peritoneum when operating
- Antibiotics
- Anticoagulants - thromboembolic prophylaxis
What operation is done in advanced GC?
We dissect based on the nodes which are affected eg. D1, D2, D3 etc
Patients with early gastric cancer treatment options
endoscopic mucosectomy- gel injected to elevate the mucosa and usind diathermy the polyp is resected.
After
Use Proton pump inhibitors and allow them to heal.
What is chromoendoscopy
chromoendoscopy is used for screening in high risk persons by injecting die to see varying appearance of mucosa in stomach
Most common site of gastric cancer
Pyloric region
Outline modes of gastric reconstruction in advanced GC.
when resecting do so 5cm above and below the tumor to create a safe margin. Take involved nodes as well
For distal stomach tumors:
BILLROTH 2 GASTRECTOMY
The resulting open end of the duodenum is closed off with staples or sutures and the jejenum is brought up and connected to the stomach in an operation called a Gastrojejunosotmy (Billroth 2 gastrectomy)
BILLROTH 1 GASTRECTOMY
The remaining stomach is joined to the exposed duodenum.
ROUX en Y
For proximal stomach tumors
May have to go into the esophagus and basically you have to do a total gastrectomy - take out the stomach and distal end of duodenum is attached to the esophojejunostomy and jejunojejunostomy. each anastamoses must be at least 8cm from each other to prevent reflux of bile up into the esophagus
what other forms of therapy exist for GC
- adjuvant and neoadjuvant chemo
- radiotherapy
- palliative surgery
post operative syndromes
- DUMPING - food goes straight into the small intestine as there is no sphincter. The patient ends up having hypotension and having to lay down after eating
- BILIOUS VOMITING
patient may get bile reflux especially with Bill Roth 2 - bile alone comes up in the mouth- no food. Bile goes up if the afferent limb becomes partialy obstructed and when this build up is releived it flies up into the esophaguus - MEGALOBLASTIC ANEMIA
this occurs in total gastrectomy , must give patient b12 supplementation parenterally - BLIND LOOP SYNDROME
With the DUodenum being a blind loop there is growth of anaerobes and they split the bile salts into bile acids which malabsorb fat which leads to diarrhea. given antibiotics to remove bacterial overload - DIARRHOEA
Intractable bilary reflux after billroth 2 is treated by
doing a roux en y
Where is iron mainly absorbed?
In the duodenum so when the duodenum is resected then there may be issues with iron absorption and an Iron deficiency anemia occurs.
Peak incidence in gastric cancer
7th decade of life
Which gastric cancer is more prevalent
distal but proximal is increasing
What causes Berkitts disease of the throat?
Ebstein Barr virus
Outline Lauren classification
- diffuse gastric adenocarcinomas - germ line- tends to be younger - CDH1 for example, signet ring cells, spread transmural spread growing thorugh the wall so intraperitoneal mets are frequent - on endoscopy you see ulcers - NO MASS
- intestinal gastric adenocarcionomas - gives a MASS and due to environmental etiologies, more common in men, increases with age - spread hematogenously
