Gastric Cancer 1

GASTRIC CANCER –1 Epidemiology: • Second leading cause of cancer-related death world-wide • USA 2-5 deaths/100,000 people, Japan 90 deaths/100,000 people • Steady decline in incidence since 1930 - improved living conditions • Incidence of proximal tumors increasing, incidence of distal tumors decreasing • Japan and Korea - 40% detected by early screening programs leading to improved survival • Associated factors o Nitrates (intestinal type) o Adenomatous polyps o Age o NSAID users - decreased incidence of non-cardia tumors o Achlorhydria o Gastritis o H. pylori § population based case-control study found 72% positively in cancer patients vs. 55% in controls § Mechanisms include: Ø tenacious binding to mucosa and promotion of inflammation Ø decreased bioavailability of vitamin C Ø association with IL1-bata secretion which is a powerful inhibitor of gastric acid secretion § Limitation of H. pylori to antrum - relatively increased acid secretion and rare development of cancer § Wide-spread H. pylori - achlorydria, atrophy Pathologic types • Intestinal o Asia o Distal o Elderly o Male o Association with atrophic gastritis o Blood-borne metastases o Better prognosis • Diffuse o West o Proximal o Young o Female o Lymphatic and peritoneal metastasis o Worse prognosis 35 Diagnosis • Endoscopy with biopsy o Early lesions flat or polypoid, late lesions ulcerated o Barium studies o CT scan| o Endoscopic ultrasound - good for wall penetration but not nodal metastasis o Laparoscopy - assess nodal and intraperitoneal spread Staging - TNM • T o T1a: lamina propria o T1b: submucosa o T2: muscularis/subserosa including omentum without serosal penetration o T3: serosal penetration o T4: adjacent organs • N o Nx: < 15 nodes evaluated o N0: no nodes o N1: 1-6 regional nodes o N2: 7-15 regional nodes o N3: > 15 regional nodes (other system ranked distance from primary tumor) § T1a - 4% LN spread § T1b - 23% LN spread § T2 - 44 % LN spread § T3 - 64% LN spread • M1: distant metastasis N0 Ia Ib II IIIa IV N1 Ib II IIIa IV IV N2 II IIIa IIIb IV IV N3 IV IV IV IV IV M0 M1 T1 T2 T3 T4 • Five year survival o Stage I - 90% o Stage II - 45% o Stage III - 15% o Stage IV - < 10% 36 Resection • Principles o Extent of gastric resection - 6 cm margin o Role of lymphadenectomy o Adequacy of margins o Role of splenectomy o Other organ involvement • Proximal tumors o Type I - cancer of distal esophagus 2-5 cm above cardia - subtotal esophagectomy, cardia, fungus, celiac nodes o Type II - cancer of true cardia - distal csophagectomy, gastrectomy, splenectomy o Type III - 2-5 cm below cardia - total gastrectomy, splenectomy, distal esophagectomy • Distal tumors o Gastric resection may be subtotal - no difference in 5 year survival o D 1 lymphadenectomy - perigastric lymph nodes o D 2 lymphadcnectomy - as above, plus celiac, common hepatic and splenic artery/hilar nodes (recommended procedure - improves staging, +/- locoregional control, assess distant lymph nodes which can result from skip metastasis) o R1 - R3 resections - performed by Japanese o R1 - stomach, omentum, perigastric LN o R2 - as above, superior leaf transverse mesocolon, pancreatic capsule, celiac and duodenal LN o R3 - as above, aortic LN, spleen, tail of pancreas o Improved survival in Japanese series never duplicated in Western studies Adjuvant and Neoadjuvant therapy - not beneficial Ulka Sachdev, M.D. March 27, 2004 37