January 16, 2007

Gastric Cancer

Synonyms and related keywords: adenocarcinoma of the stomach, gastric adenocarcinoma, gastric carcinoma, stomach cancer, Helicobacter pylori infection, H pylori infection, pernicious anemia, adenomatous polyps, chronic atrophic gastritis



INTRODUCTION

Background: Gastric cancer is the second most common cause of cancer-related death in the world. Many Asian countries, including Korea, China, Taiwan, and Japan, have very high rates of gastric cancer. More than 22,000 new cases will be diagnosed this year in the United States, making gastric cancer the fourteenth most common cancer in this country.

Gastric cancer remains a difficult disease to cure in Western countries, primarily because most patients present with advanced disease. Even patients who present in the most favorable condition and who undergo curative surgical resection often die of recurrent disease. A recent randomized study demonstrates a survival benefit with postoperative chemoradiotherapy.

Tumor biology and carcinogenesis are active areas of research investigation. The management of gastric cancer requires a thorough understanding of gastric anatomy.

The stomach begins at the gastroesophageal junction and ends at the duodenum. The stomach has 3 parts. The uppermost part of the stomach is the cardia, and the largest and middle part is called the body. The last part of the stomach, the pylorus, connects to the duodenum. These semidistinct anatomic zones have distinct histologic features. The cardia contains predominantly mucin-secreting cells. The fundus (ie, body) contains mucoid cells, chief cells, and parietal cells. The pyloric part is composed of mucus-producing cells and endocrine cells.

The stomach wall is made up of 5 layers. From the lumen out, the layers include the mucosa, the submucosa, a muscular layer, a subserosal layer, and serosal layers. The peritoneum of the greater sac covers the anterior surface of the stomach. A portion of the lesser sac drapes posteriorly over the stomach. The gastroesophageal junction has limited or no serosal covering. The right portion of the anterior gastric surface is adjacent to the left lobe of the liver and the anterior abdominal wall. The left portion of the stomach is adjacent to the spleen, the left adrenal gland, the superior portion of the left kidney, the ventral portion of the pancreas, and the transverse colon.

The site of the lesion is classified on the basis of its relationship to the long axis of the stomach. Approximately 40% of cancers develop in the lower part, 40% in the middle part, and 15% in the upper part, and 10% involve more than one part of the organ. Recently, the number of lesions discovered in the proximal aspect of the stomach and approaching or involving the gastroesophageal junction has increased. An increase in the diffuse type of gastric cancer also has been observed recently.

Pathophysiology: Understanding the vascular supply of the stomach allows understanding of the routes of hematogenous spread. The vascular supply of the stomach is derived from the celiac artery. The left gastric artery, a branch of the celiac artery, supplies the upper right portion of the stomach. The common hepatic artery branches into the right gastric artery, which supplies the lower portion of the stomach, and the right gastroepiploic branch, which supplies the lower portion of the greater curvature.

Understanding the lymphatic drainage can clarify the areas at risk for nodal involvement by cancer. The lymphatic drainage of the stomach is complex. Primary lymphatic drainage is along the celiac axis. Minor drainage occurs along the splenic hilum, suprapancreatic nodal groups, porta hepatis, and gastroduodenal areas.

Frequency:

Mortality/Morbidity: The 5-year survival rate for curative surgical resection ranges from 30-50% for patients with stage II disease and from 10-25% for patients with stage III disease. Because these patients have a high likelihood of local and systemic relapse, some physicians offer them adjuvant therapy. The operative mortality rate for patients undergoing curative surgical resection at major academic centers is less than 3%.

Race: The rates of gastric cancer are higher in Asian countries than in the United States. Japan developed a very rigorous early screening program that detects patients with early stage disease (ie, low tumor burden). These patients appear to do quite well. In fact, in many Asian studies, patients with resected stage II and III disease tend to have better outcomes than similarly staged patients treated in Western countries. Some researchers suggest that this reflects a fundamental biologic difference between the disease as it manifests in Asia and in Western countries.

Sex: Gastric cancer afflicts slightly more men than women.

Age: Most patients are elderly at diagnosis. The median age at diagnosis is 65 years (range 40-70 y). The gastric cancers that occur in younger patients may represent a more aggressive variant.


CLINICAL

History:

Physical:

Causes: Several factors are implicated in the development of gastric cancer, including diet, Helicobacter pylori infection, previous gastric surgery, pernicious anemia, adenomatous polyps, chronic atrophic gastritis, genetic factors, and previous radiation therapy. Gastric cancer most likely represents the result of multiple events occurring in an appropriate environment.


DIFFERENTIALS
Esophageal Cancer
Esophageal Stricture
Esophagitis
Gastric Ulcers
Gastritis, Acute
Gastritis, Atrophic
Gastritis, Chronic
Gastroenteritis, Bacterial
Gastroenteritis, Viral
Lymphoma, Non-Hodgkin
Malignant Neoplasms of the Small Intestine



WORKUP

Lab Studies:

Imaging Studies:

Histologic Findings: Adenocarcinoma of the stomach constitutes between 90% and 95% of all gastric malignancies. The second most common gastric malignancies are lymphomas. Leiomyosarcomas (2%), carcinoids (1%), adenoacanthomas (1%), and squamous cell carcinomas (1%) are the remaining tumor histologic types.

Staging: The 1997 American Joint Committee on Cancer (AJCC) Cancer Staging Manual presents the following TNM classification system for staging gastric carcinoma:


TREATMENT

Surgical Care:

Consultations: Specialists recommend obtaining consultations freely in the management of most malignancies, and gastric carcinoma is no exception. The gastroenterologist, surgical oncologist, radiation oncologist, and medical oncologist work closely as a team.


FOLLOW-UP

Deterrence/Prevention:

Complications:

Prognosis:

Patient Education:

1 comment:

Josue said...

The uppermost part of the stomach is the cardia, and the largest and middle part is called the body, I learned this the magazine called sildenafil citrate, health is a good magazine