Cancer is a set of diseases characterized by abnormal cell growth triggered by a genetic defect. Sometimes an infectious agent can trigger a genetic defect leading to cancer.
Deeper dive
Researchers know that genetic defects that cause cancer can be inherited, or the defects can be caused by environmental factors, such as smoking, and exposure to radiation. Infectious agents, such as viruses, bacteria and parasites also can increase a person’s risk of developing cancer.
Though the full reasons why some pathogens may increase cancer risks aren’t fully understood, researchers believe they either contribute to genetic changes in cells or inhibit the body’s ability to fight cancer. Generally, infectious diseases are linked to about 10% of cancer types, according to a 2017 Caspian Journal of Internal Medicine report.
Infectious agents known to be linked to cancer include hepatitis B and C viruses (liver cancer), Epstein-Barr virus (Burkitt’s lymphoma, nasopharyngeal carcinoma, Hodgkin lymphoma), human papillomavirus (cervical cancer), human immunodeficiency virus type 1 (Kaposi sarcoma, non-Hodgkin lymphoma, cervical cancer), Helicobacter pylori (Adenocarcinoma and lymphoma) and Streptococcus bovis (colorectal cancer).
With human papillomavirus, HPV, there is a vaccine, Gardasil, that can reduce the risk of developing cervical cancer if a person becomes infected with the virus. And treating people with antibiotics who have been infected with the bacteria H. Pylori, can reduce their risks of developing stomach cancer.
Given there are many approaches to fighting infections, from vaccines, to antibiotics, to safe sex practices, researchers are continuing to work on understanding how pathogens play a role in causing cancer.