1. Hepatitis B and C viruses (HBV, HCV)
Related cancer: primary liver cancer
Transmission route: blood transmission, mother-to-child transmission, sexual transmission
HBV and HCV infection will increase the risk of liver cancer, this has been the conclusion. Countries and regions with a high rate of hepatitis B virus infection also have a high incidence of liver cancer. When studying the blood of patients with liver cancer, it was found that 95% of patients were infected with hepatitis B and 10% were infected with hepatitis C, including some patients who were infected with hepatitis B and C at the same time, indicating that hepatitis B virus infection is closely related to the occurrence of liver cancer. Clinically, most primary liver cancers have experienced the evolution of hepatitis B virus infection, chronic hepatitis B, and liver cirrhosis.
2. Human Papilloma Virus (HPV)
Related cancers: cervical cancer, anogenital cancer and oropharyngeal cancer
Main route of transmission: Spread through sexual contact
Human papilloma virus is an epithelial globular virus, among which HPV16/18 is the most common type of cervical cancer. Cervical squamous cell carcinoma (SCCA) is mainly infected with HPV16, and HPV18 is mainly related to cervical adenocarcinoma (AC). According to relevant epidemiological statistics, the HPV positive rate is 60%-87% in the precancerous lesion group and 85%-99% in the cervical cancer group. It can be seen that cervical cancer is closely related to HPV infection. In addition, the persistent infection of high-risk HPV-16/18 is also closely related to the incidence of 50% of anogenital cancer and 20%-30% of head and neck squamous cell carcinoma.
3. Epstein-Barr virus (EBV)
Related cancers: nasopharyngeal carcinoma, lymphoma
Transmission route: saliva transmission
As early as 1997, EBV was classified as a Class I carcinogen by the International Agency for Research on Cancer, among which the most clearly related to it are nasopharyngeal carcinoma, human Burkitt lymphoma, and thyroid cancer. In recent years, a large number of studies have proved that gastric cancer, lung cancer, breast cancer and cervical cancer are also related. Studies have shown that the positive rate of EB virus nucleocapsid antigen antibody (VCA/lgA) in the serum of nasopharyngeal cancer patients around the world is as high as 90%, while the positive rate of normal people is only about 5%. The positive rate of EB virus early antigen antibody (EA/lgA) in nasopharyngeal carcinoma patients was 73%. It can be seen that nasopharyngeal carcinoma is closely related to EBV infection.
4. Helicobacter pylori (HP)
Related cancers: gastric cancer, gastric lymphoma
Transmission route: mouth-to-mouth transmission, sneeze transmission
Helicobacter pylori infection is very common. It is reported that Helicobacter pylori can be detected in the stomach of about 50% to 60% of humans worldwide. All HP-infected people will develop gastritis (gastric antrum-based gastritis or pangastritis), and 15%-20% of HP-infected people will develop peptic ulcers. The risk of gastric cancer and mucosal-associated lymphoma in HP-infected people is 2-6 times higher than that in uninfected people. A number of studies have shown that Helicobacter pylori infection in patients with gastric cancer reaches 61%-77%. Therefore, the World Health Organization has designated it as the first carcinogen of gastric cancer in 1994, and it is also an independent prognostic factor for predicting the survival of gastric cancer patients.
However, it should be clear that the occurrence of the above-mentioned types of cancer is caused by multiple factors, not just these viruses or bacteria; in fact, many people are infected with the above-mentioned viruses or bacteria. Only a small number of people will develop cancer.
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