Gastric cancer

Epidemiology
22,000 cases per year in US
Incidence is decreasing here although the incidence of GE junction cancers is increasing

Risk factors
Salted/preserved food
Lower socioeconomic status
Low intake of fruit and vegetables
Salted/preserved food
Pernicious anemia
Subtotal gastrectomy (Billroth II procedure)
H. pylori is associated with distal gastric cancer

Anatomy
Fundus/cardia: 35%
Body: 25%
Antrum: 40%

Nodes: celiac, gastrohepatic, gastroduodenal, splenic, porta hepatis, para-aortic

Pathology
90% of tumors are adenocarcinoma
Second most common type is lymphoma

Prognostic factors
T/N/M staging*
Linitis plastica
Aneuploidy (poor prognostic factor)

Surgery
Total vs. subtotal gastrectomy tested in a randomized trial (PMID 10450730) showed no survival advantage with total gastrectomy
D1 node dissection: perigastric nodes only
D2 node dissection: perigastric, splenic, celiac
D1 vs. D2 also tested in RCT (PMID 15082726) with no survival benefit seen to extended LND

Adjuvant treatment
Chemoradiation (PMID 11547741) "Macdonald trial"
Patients with T2 or greater tumors or with positive nodes after gastrectomy were randomized to chemoradiation (5FU/leucovorin + 45Gy) vs. observation
Chemoradiation was associated with:
-improved overall survival, 41% vs 50% at 3 years, median 27 vs, 36 months
-improved local control, 61% vs 19% at 3 years
-higher rates of distant metastasis as first failure, 18% vs. 33%

-Nodal targets: perigastric, celiac, local PA, porta hepatis, pancreaticoduodenal; in GE junction tumors can exclude pancreaticoduodenal nodes but must include paracardial and paraesophageal nodes; splenic nodes may be excluded if needed to spare left kidney in antral tumors.


Chemotherapy only (PMID 16822992) "MAGIC trial"
Distal esophageal as well as gastric cancer were eligible
Randomization was to perioperative epirubicin/5FU/cisplatin vs. surgery only
Chemotherapy was associated with
-improved 5-year PFS (18 vs 30%)
-improved 5-year OS (36 vs 23%)
-downstaging at the time of surgery