Gastric Cancer

Epidemiology

General

  • US has one of the lowest rates of gastric cancer among developed countries.

Risk Factors

Precursor Lesions

  1. normal tissue
  2. chronic atrophic gastritis (caused by)
    • Poor refrigeration and storage
    • High-salt intake
    • High-nitrate intake
    • H. pylori infection have 3-6 x higher risk of distal gastric cancer
    • Pernicious anemia
  3. intestinal metaplasia
  4. dysplasia

Genetic Factors

  • Li-Fraumeni syndrome (p53)
  • HNPCC

Presentation and Evaluation

Staging

Ia T1 N0
Ib T1 N1
II T3 N0 T2a/b N1 T1 N2
IIIa T4 N0 T3 N1 T2a/b N2
IIIb T3 N2
IV N3 or M1

Surgery

Gastrectomy

Radical subtotal resection (for body and antrum)

  • 80% of the stomach
  • nodes bearing tissue
  • gastrocolic and gastrhepatic omemta
  • first portion of the duodenum
  • Total gastrectomy for more proximal or larger tumors
  • if subtotal is sufficient then total is not needed.

Lymph nodes

D1 dissection

  • perigastric nodes

D2 Dissection

  • celiac
  • splenic artery
  • splenic hilar nodes

Treatment

RT Treatment field

  • Anastomses/stump must be treated
  • Pre-op tumor volume must be treated
  • Middle 1/3 or Multifocal
    • cardia, lesser curvature, greater curvature, and infrapyloric
    • pancreas (retro and head of)
    • hepatoduodenal ligament
    • splenic hilus
    • Celiac axis
  • Upper 1/3 or GE junction
    • Add paraesophageal
    • Infrapyloric may be optional for small diseases
    • Watchout for high anastomses
  • Lower 1/3 Antrum
    • Splenic may be optional
  • At least exclude 3/4 of one kidney from receiving > 20 Gy.

Post-treatment Medical Issues

  • H-2 blockers, B-12 shots, Iron, and Calcium

Studies

Peri-operative Chemotherapy (MAGIC)

  • 503 patients
  • ECF chmotherapy given over 3 months
  • 5-OS 36% vs 25% favoring peri-operative chemotherapy over surgery alone
  • 8% unable to undergo resection due to progression of disease during chemotherapy

Post-operative Chemoradiation

Mayo Clinic
Post-op: 5FU and radiation vs surgery positive for 5FU arm 20% vs 12% 5-yr OS.
Criticism: unbalanced randomization due to randomization prior to consent.

INT 0116 (Macdonald)
Eligibility

  • Completely resected adenocarcinoma of the stomach or GE junction
  • 556 patients. T2-4, N0 or T1-4, N1-3 (through muscle or involved nodes)

Treatment

Groups 3-RFS 3-OS Local-relapse Regional-relapse
CT-Surgery-CRT 48% 50% 29% 72%
Surgery alone 21% 41% 19% 65%
p-value < 0.01 < 0.01 Not Reported Not Reported

Results

  • The rate of distant metastases similar for both arms of the study.
  • 97% grade 3 or 4 toxicity (easily managed hematologic toxicity with 2 deaths)
  • 10% had formal D2 (is chemoradiation unnecessary in D2 dissection?)

Pre-operative Radiation

Bejing

  • Pre-op: radiation without chemo, and also modest radiation fields.
  • Still positive survival 30% vs 20% but high tumor bed and nodal failure.

Dublin

  • Pre-op chemoradiation vs surgery alone. Not the fraction sized used in US.
  • Low 5-yr OS in surgical arm.
Bibliography
1. Cox J, Ang K. Radiation Oncology: rationale Technique Results. 8th ed. New York: Mosby, 2003.
2. Gunderson L, Tepper J: Clinical Radiation Oncology. 2nd ed. China: Elsevier 2007.
3. Devita V, Hellman S, Rsenberg S: Cancer: Principles and practice of Oncology. 7th ed. Philadelphia: Lippincott, 2005.
4. Cunningham D, Allum WH, Stenning SP, Thompson JN, Van de Velde CJ, Nicolson M, Scarffe JH, Lofts FJ, Falk SJ, Iveson TJ, Smith DB, Langley RE, Verma M, Weeden S, Chua YJ, MAGIC Trial Participants. Perioperative chemotherapy versus surgery alone for resectable gastroesophageal cancer. N Engl J Med. 2006 Jul 6;355(1):11-20. PMID: 16822992
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