JC58 (Surgery) - Gastric Cancer Flashcards
Differentiate esophageal obstruction with gastric obstruction
Esophagus
- Presents with regurgitation, dysphagia
- Does not present with vomiting due to low volume capacity and lack of musculature to eject vomitus
Stomach
- Presents with vomiting
Compare presentation of upper, middle and lower GIT obstruction
Upper: Frequent, early vomiting Late constipation No distention Intermittent pain
Middle: Moderate vomiting Late constipation Moderate distention Intermittent pain
Late: Late vomiting Early constipation Severe distention Variable pain
S/S of upper GI obstruction
Vomit:
- not Bile-stained - obstruction proximal to ampulla of Vater
- bile stained - obstruction distal to ampulla of Vater
Epigastrium distention
Succussion splashes (pyloric outlet obstruction)
Long-term weight-loss
Gastric cancer
- Section of Stomach most commonly affected
- Demographics
Proximal stomach/ EGJ more frequently affected than body/ distal stomach
Demographic:
- Male > Female
- Increase incidence with aging
- Median age of onset at 65y
- High incidence in Asian populations
Gastric cancer
- Host risk factors
Male sex
Old age
Family history of gastric cancer (e.g. hereditary diffuse gastric CA)
Hereditary E-cadherin mutation
Previous gastric pathologies:
- Old partial gastrectomy with biliary reflux gastropathy (>20 years)
- Gastric polyps
- Chronic gastritis and atrophic gastritis: H. pylori, Pernicious anaemia, Menetrier’s disease (Hypertrophic, hypersecretory gastropathy)
Immunodeficiency syndromes e.g. CVID
Gastric cancer
Environmental risk factors
Protective factors:
H.pylori infection EBV infection Smoking (NOT alcohol) Obesity Diet: - N-nitroso compounds, salt and preserved foods, high salt intake Low socioeconomic class Industrial chemical exposure
Protective factors: vitamin C, trace elements and selenium , fibres, fresh fruits and vegetables
Histological types of gastric cancer and cells of origin
□ Adenocarcinoma (95%): classified by Lauren’s classification
» Intestinal type vs Diffuse type vs Mixed type
□ Gastric neuroendocrine tumours (carcinoids) from enterochromaffin-like (ECL) cells in mucosa
□ Gastric lymphoma from gastric MALT tissues
□ GI stromal tumours (GIST) from interstitial stromal cells
Compare Intestinal type vs Diffuse type gastric adenocarcinoma
- Demographics
- Section of stomach involved
- Risk factors
- Pathogenesis
Intestinal type:
- Elderly male
- Distal stomach
- Environmental risk factor
- Series of precursor lesions interact with environmental RFs to cause intestinal metaplasia, dysplasia and carcinoma
Diffuse type:
- Young, female
- Proximal stomach
- Risk factor: CDH-1 expression mutation, not environmental RF driven
- Hereditary diffuse gastric cancer: infiltrative signet ring cells with early transmural and lymphatic spread
Describe the intestinal type gastric adenocarcinoma pathogenesis
Compare Intestinal type vs Diffuse type gastric adenocarcinoma
Histological features
Endoscopic features
Intestinal type:
Histologically subtyped into tubular, papillary and mucinous
Usually shows expansile growth with haematogenous spread
Endoscopically appear as a fungating, polypoid or ulcerating mass
Diffuse type:
Histologically characterized by individual cells infiltrating surrounding tissues with signet ring cell formation
Usually shows infiltrative growth with transmural and lymphatic spread
Endoscopy may not show a mass: Linitis plastica (leather bottle stomach)
Linitis plastica
- Pathogenesis
- Investigations for diagnosis
Desmoplastic reaction vs rapid submucosal infiltration of tumour
□ Rigid wall w/ difficulty in insufflating stomach on OGD
□ Submucosal biopsy
□ Barium studies or CT
Common presenting features of gastric cancer (by %)
weight loss (62%), abd pain (52%), nausea (34%), dysphagia (26%), melena (20%), early satiety (18%), ulcer-like pain (17%)
Local clinical features of gastric cancer
Non-specific dyspepsia
Epigastric tenderness, mass
Epigastric distension, visible peristalsis
Early satiety, bloating, distension esp in linitis plastica
UGIB: majority occult (anaemia)
Obstruction:
□ Dysphagia in cardia tumours
□ Gastric outlet obstuction (vomiting >1h after eating, epigastric distension) for distal tumours
Fistula, eg. feculent vomiting if gastrocolic
Systemic and metastatic features of gastric cancer
Constitutional symptoms: LOW, LOA, cachexia, malaise
Metastatic S/S:
□ LN spread:
→ Virchow’s node or Troisier’s sign (Lt supraclavicular node)
→ Irish’s node (Lt axillary node)
□ Liver mets: jaundice, ascites, irregular hepatomegaly
□ Lung mets: dyspnoea (due to pleural effusion or lymphangitis carcinomatosis)
□ Peritoneal mets: ascites, Sister Joseph nodule, IO, Krukenberg’s tumour
Paraneoplastic features of gastric cancer
□ Trouseau’s sign (migratory phlebitis)
□ Leser-Trelat sign: sudden appearance of diffuse seborrheic keratosis
□ Acanthosis nigricans
□ Others: MAHA, membraneous nephropathy
Modes of gastric cancer spread
Direct invasion to pancreas, transverse colon, duodenum, Colon extension
Lymphatic spread: perigastric → coeliac → pre-aortic → Virchow’s node
Haematogenous spread: liver (most common), lungs, bones
Transcoelomic spread: indicated incurability
Features of transcoelomic spread pf gastric cancer
→ Peritoneal carcinomatosis: may be a/w ascites, palpable nodules or IO
→ Sister Mary Joseph nodule
→ Krukenberg tumour: metastatic ovarian tumour from GI primary
→ Blumer’s shelf: ‘shelf-like’ POD tumour deposit felt at anterior rectal wall on PR
4 molecular subtypes of gastric cancer
EBV - Male predominant
MSI - Female predominant, old age
GS - Diffuse histology enrichment, recurrent CDH1 and RHOA mutation, inactivating ARID1A mutation
CIN (most common) - Intestinal histology, with RTK-Ras amplification, phosphorylation of EGFR
Diagnostic investigations for suspected gastric cancer
Gold standard: OGD + mucosal/ submucosal biopsy at 4 quadrants of ulcer edge
Supportive tests: CBP, LFT, RFT, CXR
(Double contrast barium study (poor false negative rate): visualize ulcers, infiltrating lesions)
Name one staging system for gastric cancer
Function of staging
Staging: AJCC8 TNM staging
□ Early CA stomach, i.e. T1N0 → endoscopic Tx
□ Resectable locoregional → gastrectomy
□ Unresectable locoregional or metastatic → palliative Tx
Staging investigations for gastric cancer
Staging evaluation: r/o metastasis before proceeding to other Ix
- Ultrasound or CT abdomen
- Liver function test: hepatic metastasis
- Chest X-ray: thoracic metastasis
- PET/CT scan: distant metastasis
- Endoscopic ultrasound: T/N staging
- Staging Laparoscopy: peritoneal metastasis
Serum tumor markers for gastric cancer
Function and limitations
Serum tumour markers: CEA, CA 19-9, CA72-4
→ Low Sens/Spec, NOT diagnostically useful
→ May be useful as serial monitoring for Tx response
Treatment options for gastric cancer based on resectability
Curative treatment for resectable tumours
→ Endoscopic resection for early CA stomach (T1, any N)
→ Gastrectomy ± adjuvant for resectable invasive CA stomach
Palliative treatment for unresectable tumours
→ Chemotherapy for systemic disease control
→ Local palliation for local complications
Criteria for Unresectable gastric cancers
□ Presence of distant metastasis, including LNs outside surgical field (eg. retropancreatic LNs)
□ Invasion of major vascular structures, eg. aorta
□ Encasement/occlusion of coeliac axis, proximal splenic a. or hepatic a.
(Distal splenic artery involvement is NOT an indicator of unresectability)
Treatment options of early, limited, Resectable gastric cancer
□ Endoscopic mucosal resection (EMR): snare resection of lesion after saline injection to elevate lesion
□ Endoscopic submucosal dissection (ESD): region of mucosa dissected away at submucosa level after saline injection
→ Allow en-bloc resection with risk of perforation
→ Used for polypoid or large lesions
Treatment options for resectable, invasive gastric cancer
Surgery:
- radical gastrectomy (open/lap gastrectomy + LN)
- reconstruction (laparoscopic assisted or total laparoscopic; hand sewn or stabled)
Systemic:
- Neoadjuvant chemo: considered for all potentially resectable tumours ≥T2
- Adjuvant chemo-RT: indicated for T3N0 or N1, chemo (FOLFOX) followed by chemo/RT (capecitabine or FU)
Post- gastrectomy management for gastric cancer
Regular F/U w/ monitoring by CEA/CA-125 and imaging studies
Postgastrectomy diet: small frequent meals, avoid high carbohydrate meals (dumping)
Nutritional supplementation:
- B12, Iron, Calcium, Fat soluble vitamin
Gastrectomy for gastric cancer removal
- Extent of excisions
- Extent of LN dissection
- Reconstruction methods
Extent of excision: ligate Lt/Rt gastric, Lt/Rt gastroepiploic vessels
→ Distal gastrectomy for distal lesions
→ Total gastrectomy for proximal lesions
Extent of LN dissection: D2 (extended) dissection
→ i.e. clearance of major arterial trunks
Reconstruction: 1 limb for B1, 2 limbs for B2
Billroth I = end-to-end gastroduodenostomy for distal gastrectomy
Billroth II = gastrojejunostomy for distal gastrectomy
Roux-en-Y = esophago- or gastrojejunostomy + jejunojejunostomy (Bohn anastomosis) for total gastrectomy
Treatment options for unresectable gastric cancer
Supportive: pain control, feeding care
Systemic: only if functional status satisfactory
→ 1st line: chemotherapy ± trastuzumab (if HER2 +ve)
→ Other options: targeted therapy, immunotherapy
Local: to palliate complications
→ Obstruction: EBRT, endoscopic stenting or ablation (for dysphagia), surgical bypass (GJ)
→ Haemorrhage: endoscopic therapy, transcatheter embolization, EBRT
→ Regional intra-arterial chemotherapy
→ Palliative gastrectomy if less-invasive strategies fail
Compare endoscopic stenting vs surgical bypass for Gastric cancer palliation
