Stomach Cancer

 

STOMACH CANCER

Overview

The stomach is a sack like organ that holds food and begins the digestive process by secreting gastric juices. The food and gastric juice are mixed and then emptied into the first part of the small intestine called the duodenum.

The stomach is divided into five sections. The upper portion (closest to the esophagus) is the proximal stomach. Some cells of this area of the stomach produce acid and pepsin ( a digestive enzyme), the ingredients of the gastric juice that helps digest food. The lower portion is the distal stomach. This area includes the antrum, where the food is mixed with gastric juices, and the pylorus, which acts as a valve to control emptying of the stomach contents into the small intestine. Other organs next to the stomach include the colon, liver, spleen, small intestine, and pancreas.

The stomach has five layers. The innermost layer is called mucosa, in mucosa stomach acid and the digestive enzymes are made. Next layer is called submucosa. Submucosa is surrounded by muscularis, a layer of muscle that moves and mixes the stomach contents.

The next two layers, the submucosa and outermost serosa act as wrapping layers for the stomach. Most stomach cancers start in the mucosa. Stomach cancers develop slowly over many years. Stomach cancers can spread or metastasize, in different ways. They can grow through the walls of the stomach and eventually grow into the nearby organs. They can also spread to the lymph nodes. Of cancer spreads to the lymph nodes the chances of cure also becomes less. In later stages the stomach cancer will travel through the blood stream and form metastasis in organs such as liver, lungs, and bones. Even if it has spread to other organs it is still called stomach cancer. 

Majority of stomach cancers are adenocarcinoma. They develop from the epithelial cells that form the epithelial cells that form the innermost lining of the stomach’s mucosa.

The other less frequently occurring cancers of the stomach are.

(a) Lymphoma

(b) Gastrointestinal stromal tumors

(c) Carcinoid tumors 

Risk factors

(i) Age: - Most cases of stomach cancers can occur in people over age 55.

(ii) Gender: - Men have double the risk of developing stomach cancer as compared to women.

(iii) Family history: - People who have a first degree relative who has had stomach cancer are at an increased risk for stomach cancer.

(iv) Diet: - Consuming foods preserved with preservatives can increase the risk of developing stomach cancer. Eating fresh fruits and vegetables can reduce the risk of developing stomach cancer.

(v) Bacteria: - A type of bacteria called H-pylori, which causes stomach inflammation and ulcers, may increase the risk of stomach cancers. However most people infected with this disease never develop stomach cancer.

(vi) Previous surgery or health conditions: - People who have had stomach surgery or pernicious anemia (severe decrease in red blood cells) or achlorhydria (absence of hydrochloric acid in the gastric juices) which helps digest food have an increased risk of stomach cancers.

(vii) Occupational exposure: - Exposure to certain dusts and fumes may increase the risk of developing stomach cancer.

(viii) Obesity: - Excess body weight increases the risk for stomach cancer. 

Symptoms

(i) Indigestion or heartburn

(ii) Pain or discomfort in the abdomen

(iii) Nausea and vomiting

(iv) Diarrhea or constipation.

(v) Bloating of the stomach after meals

(vi) Loss of appetite

(vii) Weakness and fatigue

(viii) Vomiting blood or having blood in the stool

(ix) Unintended weight loss

These symptoms can also be caused by many other illnesses, such as a stomach virus or an ulcer. People with these symptoms should get a thorough check-up. 

Diagnosis

(a) Upper endoscopy

(b) Imaging studies

(c) Barium swallow

(d) Endoscopy

(e) Computed tomography

(f) Magnetic resonance imaging

(g) X-Ray 

Stages

(i) Stage 0: - Carcinoma in situ. Cancer cells are limited to the mucosa (innermost layer of the stomach) and have not invaded deeper layers of the stomach.

(ii) Stage I: - Tumor invades underneath the mucosa, into the lamina propria or submucosa.

(iii) Stage II: - Tumor invades the muscle layer below the mucosa and lamina propria, or tumor invades the subserosa (layer between the muscle layer and serosa)

(iv) Stage III: - Tumor perforates the serosa but does not invade any adjacent organs.

(v) Stage IV: - Tumor perforates the serosa and invades an adjacent organ or other structures such as major blood vessels.