Gastric Carcinoma

Incidence/Prevalence

Adenocarcinoma - 90% intestinal (decreasing trend) diffuse (increase trend)

Non-Hodgkin's lymphoma - 6% GIST Carcinoid Squamous cell Ca

Incidence/Prevalence

3rd most common GI malignancy (after colorectal and pancreatic)

Second causes of death from cancer

lung (17.8 %), gastric (10.4 %), and liver (8.8 %)

The worldwide incidence of gastric cancer has declined rapidly over the recent few decades

Part of the decline may be due to the recognition of certain risk factors such as H. pylori and other dietary and environmental risks

Despite the decline, the absolute number of new cases per year is increasing

GEOGRAPHICAL VARIATION

The incidence of gastric cancer varies with different geographic regions.

Approximately 60 percent of gastric cancers occur in developing countries

The highest incidence rates are in Eastern Asia, the Andean regions of South America, and Eastern Europe

Japan & S. America 75 & 150 / 100,000 US & W.Europe 8 & 15 / 100,000

Incidence/Prevalence

Early Gastric Carcinoma

Japan 40 %

United States 6 -10 %

Incidence/Prevalence

Slowly developing

Usually discovered in advanced stages

Men>Women

Occurs between the ages of 50-70

ENVIRONMENTAL RISK FACTORS 

 Emigrants from high-incidence to low-incidence countries often experience a decreased risk of developing gastric carcinoma.

Diet  Foods such as pickled vegetables, salted fish and meat, smoked

foods and salt

Salt — High salt intake damages stomach mucosa and increases the susceptibility to carcinogenesis in rodents

Dietary nitrates (bacteria in stomach breaks down nitrites to compounds that are carcinogenic in animals)

ENVIRONMENTAL RISK FACTORS 

• People who smoke cigarettes or use alcohol are 1.5 times more likely

Socioeconomic status 

-The risk of distal gastric cancer is increased by approximately twofold in populations with low socioeconomic status

- By contrast, proximal gastric cancers have been associated with higher socioeconomic class

ENVIRONMENTAL RISK FACTORS 

H. pylori: Important in the etiology of peptic ulcers and gastric cancer Found in 60 percent of gastric carcinomas

Gastric surgery  increased risk of gastric cancer after gastric surgery

Billroth II procedure , with the risk being greatest 15 to 20 years after surgery

RISK FACTORS 

Gastric polyps  Gastric ulcer Genetic factors include:

First degree relatives Type A blood

Pernicious anemia

Anatomy of Stomach

Cardia

Body

Antrum

Pylorus

Stomach-normal histology

Parietal cells - in body produce HCl Chief cells - in body - pepsinogen Mucous cells - all over - mucus G cells-in antrum - gastrin

Anatomy of the stomach

Location

37% in the proximal third of the stomach 30% in the distal stomach 20% in the midsection Remaining 13% in the entire stomach

Gastric Carcinoma Lauren Classification

There are two main histologic variants of gastric adenocarcinoma.

The most frequent is the "intestinal type", so called because of its morphologic similarity to adenocarcinomas arising in the intestinal tract.

The less common diffuse type gastric cancers

Gastric Carcinoma Lauren Classification Intestinal

patients greater than 50, male>female arises from metaplastic glands in chronic gastritis;

associated with H. pylori incidence decreasing in USA

Diffuse (signet ring cell, linitis plastica) younger patients, no gender preference not associate with H. pylori incidence increasing

Intestinal type

One model for the "intestinal type" of gastric cancer describes a progression from chronic gastritis to chronic atrophic gastritis, to intestinal metaplasia, dysplasia, and eventually to adenocarcinoma

Morphologic types of Carcinoma Stomach

Fungating

Ulcerating

Diffuse

Ulcerated gastric adenocarcinoma

Thickened “linitis plastica” type adenocarcinoma infiltrating gastric wall

Physical Assessment

Early gastric cancer Abdominal discomfort initially relieved with antacids Feeling of fullness Epigastric, back, or retrosternal pain NOTE: most people will show no clinical

manifestations

Symptoms of Gastric Disorders

Heartburn Epigastric pain Dyspepsia (upset stomach) Vomiting Hematemesis

Frequently “coffee-ground” emesis Melena

Physical Assessment

Advanced stage:

Nausea/vomiting Obstructive symptoms Iron deficiency/anemia Palpable epigastric mass Enlarged lymph nodes Weakness/fatigue Progressive weight loss

DIAGNOSIS 

Esophagogastroduodenoscopy

- Polypoid mass

- Ulcer crater

- Thickened fibrotic gastric wall

Preoperative evaluation

Abdominopelvic CT scan 

Endoscopic ultrasonography 

Chest CT For patients with a proximal gastric cancer

PET scan Sensitivity of PET scans for the detection of peritoneal

carcinomatosis is only about 50 percent.

 Staging laparoscopy  Between 20 and 30 % of patients who have disease that is beyond T1

stage on EUS will be found to have peritoneal metastases despite having a negative CT scan

Gastric carcinoma

Tumor Node Metastasis

T1 invades lamina propria or submucosa

N0 no mets in LN M0 no distant mets

T2 invades muscularis propria or subserosa

N1 mets in perigastric LN 1-6 LN

M1 Distant mets

T3 penetrates serosa

N2 mets in perigastric LN7 – 15 LN

T4 invades adjacent organs

N3 mts to > 15 LN

STAGE GROUPING

Stage 0 Tis N0 M0

Stage 1A T1 N0 M0

Stage IB T1 N1 M0

T2a/b N0 M0

Stage II T1 N2 M0

T2a/b N1 M0

T3 N0 M0

Stage IIIA T2a/b N2 M0

T3 N1 M0

T4 N0 M0

Stage IIIB T3 N2 M0

Stage IV T4 N1–3 M0

T1–3 N3 M0

Any T Any N M1From AJCC Cancer Staging Manual, 6th ed. New York, Springer-Verlag, 2001.

Spread of Gastric Ca

Spreads through stomach into the gastric wall to the Lymph nodes Pancreas Transverse colon

Omentum

Through portal vein into Liver

Through systemic circulation into lungs, and bone Peritoneum Ovaries Pelvic cul-de-sac Distant Lymph nodes

Spread of Gastric Ca

Physical signs – advanced or mts Palpable abdominal mass Palpable supraclavicular (Virchow’s) LN Palpable periumbilical (Sister Mary Joseph’s) LN Peritoneal mets palpable by rectal exam (Blumer’s

shelf) Palpable ovarian mass (Krukenberg’s tumor) Hepatomegaly

Clinical Presentation

Surgical Treatment

Absence of distant mts

Patient with distant mts but with complicated tumor

Line of resection at least 6 cm from the tumor mass to decrease recurrence at anastomosis

Carcinoma of Stomach

Surgical options

Total gastrectomyProximal tumoursMid-body tumours

Subtotal gastrectomy Distal tumours

Omentectomy

Distal Tumors

Account for ~ 35 % of all gastric cancers

No 5-year survival difference b/n subtotal vs total gastrectomy

Subtotal appropriate if negative margins Recurrence vs nonrecurrence depends on margin of

3.5 cm vs 6.5 cm margins 4 – 6 cm 10% involvement margins 2 cm 30 %

Proximal Tumors

Cardia / proximal ~ 35-50% of gastric adenocarcinomas

Proximal More advanced at presentation Curative resection is rare Total gastrectomy

Palliation

20 – 30% of gastric cancer presents as stage IV disease

Surgical palliation

Percutaneous, endoscopic, radiotherapuetic techniques

Nonoperative tx Laser recanalization, endoscopic dilatation (+/-

stent)

Carcinoma of Stomach

Surgical treatment Overall 5 year survival rate 10 – 21% in western

series Japanese series 50%

Adjuvant therapy (postoperative) Neoadjuvant therapy (preoperative)

Response rates vary from 21 –31% clinical response rate to complete response rate of 0-15%

Adjuvant Therapy

Southwest Cancer Oncology Group trial

5-FU, Leucovorin w/ chemorad for R0

3 yr survival 41% Chem/Rad 3 yr survival 50%

28% benefit in survival

Gastric Carcinoma - Natural History

2/3 of patients have locally advanced or metastatic disease at diagnosis

50% recurrence following curative surgery

Adjuvant Chemo + R/T improves survival

Recurrence

After gastrectomy quite high 40 – 80 % Most occur w/in first 3 years Locoregional failure 38 – 45%

Anastomosis, gastric bed and regional nodes

Peritoneal dissemination – 54%

Annual endoscopy for subtotal gastrectomy

Gastric Carcinoma

Prognosis invasion is most important factor

early: limited to mucosa and submucosa; 90-95% survival at 5 years

late: beyond submucosa; less than 10 - 30% survival at 5 years

Five-year survival 95 % for patients with superficial T1 tumors and

negative lymph nodes (stage IA disease) 7 - 8 % for patients with N3 nodes or any distant

metastases LN Dissection