Gastric Cancer 2

GASTRIC CANCER - 2 Epidemiology • 21,700 new cases of adenocarcinoma of the stomach in the US • 12,800 deaths due to the disease • 10th most common cancer in the US • 10/100,000 in the US vs 78/100,000 in Japan • Survival remains poor Risk Factors • Diet - salt and smoked foods • Male, blacks, lower socioeconomic class • Occupational - metal workers, miners and rubber workers and dust from wood and asbestos • Cigarette smoke - decreased levels of vitamin C • Blood group A and familial clustering has been reported as well. • Pernicious anemia 10 % incidence of Gastric cancer • Chronic atrophic gastritis • Genetic alterations - p-53 expression H. Pylori - implicated in the genesis of gastric cancer • 90% of patients with intestinal type gastric cancer • 32% of patients with diffuse type gastric cancer • Infection of greater than 10 years Pathology • 95% adenocarcinoma - mucus producing cells of gastric mucosa • 5% - lymphoma, carcinoma, leiomyosarcoma and squamous cell Intestinal type and Diffuse Clinical Presentation • Lacks specific symptoms - anorexia, pain, weight loss, hematemesis- nausea, vomiting, dysphagia • Advanced disease - Rapid weight loss, anorexia. and vomiting • 10% present with evidence of metastatic disease • Virchow's node, Blumer's shelf, Sister Mary Joseph’s node, • Ascites, jaundice, a 1iver mass or a pelvic mass Diagnosis and Staging • History and Physical, Laboratory (anemia, LFTs) • EGD -allow simultaneous visualization and biopsy • CT- low sensitivity for <5mm lesions, good for distant metastases • EUS (80% sensitivity for T1, 50% for Lymph nodes ) - specialized centers • Laparoscopy +/- laparoscopic Ultrasound (25% reduction in non-therapeutic laparotomies). 38 • • Peritoneal cytology PET Tis- mucosa, no penetration to lamina propria T1- invades mucosa or submucosa T2- invades muscularis propria or subserosa serosa T3- through scrota, no invasion of contiguous structures T4- invading adjacent structures N0 – no regional lymph node metastases N1 – 1-6 lymph nodes N2 – 7-15 lymph nodes N3 > 15 lymph nodes M0 – no distant metastases M1 – Distant Metastases Stage 0 Stage 1A Stage 1B Stage 2 Stage 3A Tis T1 T1 T2 T1 T2 T2 T3 T4 T3 T4 any T N0 N0 N1 N0 N2 N1 N2 N1 N0 N2 N1-3 any N M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M1 Stage 3B Stage 4 Treatment : Surgery, Lymph node dissection, Adjuvant and neoadjuvant therapy Surgical Treatment • Treatment - primarily surgical. • Cure requires removal of all gross tumor with free margins. - 6 cm margin • Proximal tumors- 35-50% of tumor, more advanced, poor prognosis Frequently palliative TG or proximal STG Roux en Y • Mid Body tumors- 15-30%, Total gastrectomy, Roux en Y • Distal tumors- 20- 35% Distal STG (75% of stomach) 5-6 cm margin 39 R status- Residual disease R0, R1 and R2 • D1 - perigastric lymph nodes ( 1-6) • D2- left gastric, common hepatic, celiac axis, splenic hilum, splenic artery (7- 11) • D3- HDL, retropancreatic, root of small bowel mesentery, paraaortic, transverse mesocolon 1981 - Kodama- increased survival with D2/ D3 rx. vs D1 ( 39% vs 18% 5ys ) • Results not repeated in western studies • Reasons: Meticulous nodal dissection in Japan Understaging in western countries Mass screening- early detection in Japan Different biology of tumor Adjuvant therapy • 80% develop recurrence (after potentially curative resection) References: Wanebo J.Am.Coll.Surg. 1996:183:616-624 • 18,346 gastric cancer patients, 200 centers • D2 LND- no increase in median survival time or 5year survival (D2- 26%, D 1 – 30%) Dutch Gastric Cancer Group, NEJM, l999:340:908-914 • 711 patients randomized to D1 and D2 • Higher mortality and complication rate with extended LND M.D. Anderson Surgical Oncology Handbook 40