Cancer Research. The Biology of Gastric Cancer

Literature Review , 2017 , 8 Pages

Medicine - Pathology

From a pathological perspective, cancers occur due to the failure of the immune system. It is evident that the immune system plays key roles in preventing cancer through regulating cell population in the body. Ordinarily, the body’s immune system is usually involved in some cellular processes, especially in the cell cycle in which it destroys old or defective cells through programmed cell death, a process commonly known as apoptosis. In the context of cancer, this process is usually impaired, thus damaged or defective cells are not destroyed by the immune system. In addition, the impairment of the immune system’s activity affects cellular homeostasis processes including irregular cell division. These factors are responsible for tumor growth and progression of cancer. Gastric cancer affects the digestive system, primarily the stomach. Anatomically, the stomach occupies the region from the esophageal junction to the duodenum. Therefore, aim of this research is to carry out a comprehensive review of gastric cancer, also known as stomach cancer.

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Inhaltsverzeichnis

Introduction ... 3

Biological Changes during Onset and Progression of Gastric Cancer ... 3

Distinctive Characteristics of Cancer Cells ... 5

Effect of Gastric Cancer in the Body ... 5

Therapies for Gastric Cancer ... 6

Lifestyle Changes in Gastric Cancer Prevention and Treatment ... 7

Relationship between Gastric Cancer and other Cancers ... 7

References ... 8

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Introduction

From a pathological perspective, cancers occur due to the failure of the immune system.

It is evident that the immune system plays key roles in preventing cancer through regulating cell

population in the body (Dicken et al., 2005). Ordinarily, the body's immune system is usually

involved in some cellular processes, especially in the cell cycle in which it destroys old or

defective cells through programmed cell death, a process commonly known as apoptosis. In the

context of cancer, this process is usually impaired, thus damaged or defective cells are not

destroyed by the immune system. In addition, the impairment of the immune system's activity

affects cellular homeostasis processes including irregular cell division. These factors are

responsible for tumor growth and progression of cancer. Gastric cancer affects the digestive

system, primarily the stomach. Anatomically, the stomach occupies the region from the

esophageal junction to the duodenum (Cabebe, 2015). Therefore, aim of this research is to carry

out a comprehensive review of gastric cancer, also known as stomach cancer.

BiologicalChangesduringOnsetandProgressionofGastricCancer

In gastric cancer, biological cellular changes occur due epigenetic modification of genes

involved in maintaining the integrity of cells. These genetic alterations are responsible for

changes in cell structure and behavior. One of the key changes caused by mutations of the key

genes in gastric cells is changes in gene expression. It is apparent that gene alterations influence

the amount of cellular proteins produced by gastric cells. Second, genetic alterations result into

the production of defective or abnormal protein products that do not play their cellular biological

roles or alter the function of other proteins in the cell. In gastric cancer, there are several

molecules which structural alterations. Some of these molecules include the cell cycle regulator

(cyclin E) the apoptosis inhibitor (bcl-2), multifunction protein (beta-Catenin), epidermal growth

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factor, cell adhesion protein (E-cadherin), and plasmolagen activator. On the other hand, some of

these molecules exhibit alterations in gene expression. For instance, gastric cancer cells exhibit

gene amplification that is responsible for overexpression of K-sam and c-erbB2 proteins which

act as growth factor receptors (Becker, Keller & Hoefler, 2000).

Some of the key genes whose epigenetic modifications lead to the development of gastric

cancer are CDH1 gene, TP53 gene and APC gene. CDH1 regulates the expression E-cadherin of

epithelial cadherin which is involved in cell-cell adhesion, cell movement and cell signaling.

Therefore, gene alterations on CDH1 impair the development of organized tissues due to changes

in cytoskeletal structures. These alterations have also been found to lead to the development of

gastric cancer because it acts as a tumor suppressor gene. On the other hand, mutations on TP53

gene lead to the production of abnormal p53 protein which plays key roles in immune system

surveillance. Clinical investigations reveal that TP53 protein is either lost or damaged in 80

percent of gastric cancers. Finally, alterations in APC gene impairs cell signaling within gastric

cells (Zheng, Wang, Ajani & Xie, 2004).

At the organ level, gastric cancer causes several biological changes. Clinical studies

indicate that noncohesive tumor cells infiltrate the stomach wall. This process leads to glandular

formation that does not function as normal gastric glands. In addition, lesions occur on the

gastric wall in which diffuse tumors cause inflammation and desmoplasia (Dicken, Bigam, Cass,

Mackey, Joy & Hamilton, 2005). Moreover, notch signaling in gastric tumorigenesis appears

specific for gastric cancer (Kim & Shivdasani, 2011).

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DistinctiveCharacteristicsofCancerCells

In practice, the appearance of tissues and organs is determined by the types and

arrangement of cells that constitute specific tissues or organs. Cancer is usually identified on the

basis of the normal appearance of tissues. Therefore, the distinction between characteristics of

cancer cells and normal cells is paramount in pathological investigations of cancer. From a

pathological perspective, a comprehensive distinction can be guided by three core features; shape

and size of the cells, nucleus appearance and the arrangement of cells in tissues. Ordinarily,

normal cells exhibit consistency in the size and shape. In contrast, cancer cells lack consistency,

they are either smaller or larger than normal cells, and their shapes are distorted due to

cytoskeletal changes. Second, cancer cells have larger and darker nucleus compared to normal

cells. Finally the arrangement of normal cells possesses characteristics which are specific to a

certain tissue or organ. For instance, gastric cells form glands that produce mucus to protect the

gastric wall, digestive enzymes and gastric acid that aid digestion. In contrast, gastric cancer

cells form distorted glands. Another significant difference between normal gastric cells and

gastric cancer cells is that, normal cells are localized implying that they stay within the gastric

walls. This localization is absent in gastric cancer cells because they spread to other surrounding

tissues during the progression of the disease, a phenomenon known as metastasis (Duffy,

McGowan & Gallagher, 2008).

EffectofGastricCancerintheBody

The pathophysiology of gastric cancer explains how the disease affects the body as it

progresses. The enlargement of tumors disrupts stomach distension and bowel obstruction. In

some cases of ulcerative tumors, bleeding occurs, and this is manifested as melena,

gastrointestinal hemorrhage or hematemesis. In advanced gastric cancer, ascites and

• College: Egerton University
• Author: Patrick Kimuyu (Author)
• Publication Year: 2017
• Pages: 8
• Catalog Number: V384370
• ISBN (eBook): 9783668626409
• ISBN (Book): 9783668626416
• Language: English
• Tags: cancer, research, biology, gastric