Infectious causes of cancer

Overview

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Electron micrograph of Helicobacter pylori, a bacterium linked to gastric cancer.

Infectious causes of cancer refer to cancers that are initiated or promoted by infectious agents, including viruses, bacteria, and parasites. These agents can lead to cancer by causing chronic inflammation, altering the host cell's genetic material, or suppressing the immune system.

Viral Causes

Several viruses are known to be associated with cancer in humans. These include:

• Human papillomavirus (HPV): Certain strains of HPV are linked to cervical cancer, as well as cancers of the anus, oropharynx, and other genital areas.
• Hepatitis B virus (HBV) and Hepatitis C virus (HCV): Both viruses are associated with liver cancer, also known as hepatocellular carcinoma.
• Epstein-Barr virus (EBV): This virus is linked to several types of cancer, including Burkitt's lymphoma, nasopharyngeal carcinoma, and some forms of Hodgkin's lymphoma.
• Human T-lymphotropic virus type 1 (HTLV-1): Associated with adult T-cell leukemia/lymphoma.
• Kaposi's sarcoma-associated herpesvirus (KSHV): Linked to Kaposi's sarcoma, a cancer that often affects individuals with compromised immune systems, such as those with HIV/AIDS.

Bacterial Causes

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Helicobacter pylori infection is a major risk factor for gastric cancer.

Certain bacteria have been implicated in the development of cancer:

• Helicobacter pylori: This bacterium is a well-known cause of gastric ulcers and is strongly associated with gastric cancer. Chronic infection with H. pylori can lead to inflammation and changes in the stomach lining, increasing the risk of cancer.

Parasitic Causes

Some parasites are also linked to cancer development:

• Schistosoma haematobium: Infection with this parasite is associated with bladder cancer, particularly in regions where schistosomiasis is endemic.
• Opisthorchis viverrini and Clonorchis sinensis: These liver flukes are linked to cholangiocarcinoma, a cancer of the bile ducts.

Mechanisms of Carcinogenesis

Infectious agents can contribute to cancer through several mechanisms:

• Chronic Inflammation: Persistent infection can lead to chronic inflammation, which may result in DNA damage and promote cancer.
• Genetic Alterations: Some viruses integrate their genetic material into the host genome, disrupting normal cellular functions and leading to cancer.
• Immune Suppression: Certain infections can weaken the immune system, reducing its ability to detect and destroy cancerous cells.

Prevention and Control

Preventing infections that can lead to cancer involves vaccination, safe practices, and early treatment of infections. For example, vaccines are available for HPV and HBV, which can significantly reduce the risk of related cancers.

Related Pages

• Cancer
• Oncogenic virus
• Chronic inflammation
• Immune system