Most of the causes of cancer are not clear, which poses a great challenge for treatment. If the exact cause is known and the pathway of cancer is cut off early, the incidence of cancer can be effectively reduced and cancer treatment will be easier! According to the International Agency for Research on Cancer, bacteria and viruses are responsible for about 1/6 of all cancers in the world. Among the infections that cause cancer in human body, there are 4 main types of bacteria and viruses, they are hepatitis B and C viruses, human papilloma virus, EBV and Helicobacter pylori, which mainly cause liver cancer, cervical cancer, nasopharyngeal cancer and stomach cancer. Statistics show that these pathogens alone caused nearly millions of people worldwide to develop cancer that year. 4 types of bacteria and viruses that cause cancer 1. Hepatitis B and C viruses (HBV, HCV) Associated cancers: Primary liver cancer Transmission routes: blood-borne, mother-to-child, sexual HBV and HCV infections increase the risk of liver cancer, and this is a foregone conclusion. Countries and regions with high rates of hepatitis B virus infection also have high rates of liver cancer. When studying the blood of liver cancer patients, 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 both hepatitis B and hepatitis C. This indicates that hepatitis B virus infection is closely related to the occurrence of liver cancer. Most primary liver cancers in clinical practice have experienced the evolution of hepatitis B virus infection, chronic hepatitis B and liver cirrhosis. 2.Human papillomavirus (HPV) Associated cancers: cervical cancer, anal genital cancer and oropharyngeal cancer Main transmission route: transmitted through sexual contact Human papillomavirus, an epitheliophilic globular virus, of which HPV16/18 is the most common type of cervical cancer. Squamous cervical cancer (SCCA) is mainly infected with HPV type 16, while HPV18 is mainly associated with cervical adenocarcinoma (AC). According to the epidemiological statistics of relevant data, the HPV positivity rate is 60%-87% in the precancerous group and 85%-99% in the cervical cancer group. This shows the close relationship between cervical cancer and HPV infection. In addition, persistent infection with high-risk HPV-16/18 is also closely associated with the development of 50% of anal genital cancers and 20%-30% of head and neck squamous cancers. 3.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, and the most clearly related to it are nasopharyngeal carcinoma, human Burkitt’s lymphoma, and thyroid cancer. In recent years, numerous studies have demonstrated associations with stomach, lung, breast and cervical cancers. Studies have shown that the serum positivity rate for antibodies to EBV nucleosome antigens (VCA/lgA) in patients with nasopharyngeal carcinoma worldwide is over 90%, compared to about 5% in normal subjects, and the positivity rate for antibodies to EBV early antigens (EA/lgA) in patients with nasopharyngeal carcinoma is 73%. This shows how close nasopharyngeal cancer is 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 about 50% to 60% of the world’s people can be detected in the stomach of H. pylori. The risk of gastric cancer and mucosa-associated lymphoma is two to six times higher in HP-infected patients than in uninfected people. A number of studies have shown that H. pylori infection is present in 61-77% of gastric cancer patients, making it the number one carcinogenic factor in gastric cancer by the World Health Organization in 1994, and an independent prognostic factor in predicting survival in gastric cancer patients. However, it should be clear that the occurrence of these types of cancers is due to multiple factors, and not only these viral or bacterial infections; in fact, many people are infected with these viral or bacterial infections, and only a small number of people will develop cancer. How to prevent cancer caused by viral or bacterial infections? 1. Vaccination Human beings have developed hepatitis B vaccine and HPV vaccine, which are the only two vaccines that can effectively prevent cancer in the world. Since the implementation of measures such as hepatitis B vaccination in infancy, the number of hepatitis B virus carriers in China has been reduced and the incidence of liver cancer has been lower than before as a result. Not long ago, GlaxoSmithKline (GSK) announced that the first cervical cancer vaccine approved in China, Hirex, was officially launched. For women aged 9-25 years old, they can receive the cervical cancer vaccine, and the best effect is to receive the vaccine before having sex, and to complete three vaccinations within six months. 2, pay attention to dietary hygiene Helicobacter pylori is highly infectious and can be transmitted through hands, unclean food, unclean utensils, feces, etc. Therefore, it is necessary to develop good hygienic habits in daily diet to prevent infection; it is recommended that communal chopsticks and spoons be used as far as possible when gathering for meals, and it is best to implement a meal-sharing system; patients with chronic gastritis should avoid feeding young children orally; patients also need to pay attention when kissing with others. 3, timely treatment of chronic hepatitis B reasonable antiviral treatment and prevention of cirrhosis is very important, can effectively control and delay the occurrence of cirrhosis and liver cancer. Patients with gastritis combined with HP infection should consult the gastroenterology department to clarify whether they need to receive anti-HP treatment and the time of follow-up gastroscopy. Early treatment of precancerous lesions of gastric cancer and cervical cancer can effectively reduce the occurrence of cancer. 4. High-risk groups should have regular cancer screening Anyone infected with hepatitis B and C viruses, human papilloma virus, EB virus and Helicobacter pylori are considered as high-risk groups for the corresponding cancers, and regular medical checkups should be conducted to detect early cancers and achieve the goal of early diagnosis and early treatment. (1) For patients with chronic hepatitis B infection, liver function, quantification of hepatitis B virus and methemoglobin should be checked every 3 months, and liver ultrasound should be performed every 6 months, etc. (2) The age of cervical cancer screening for women should start from 21 years old. For women in the age group of 21-29 years old, cytological screening is recommended every 3 years, and for women in the age group of 30-65 years old, cytological screening is recommended every 3 years or HPV testing combined with cytological screening every 5 years. If HPV-positive, follow up with 12 months combined screening or further HPV-16 or HPV-18 typing: colposcopy is recommended if HPV-16 or HPV-18 is positive. (3) Since EBV antibodies are elevated more than 3 years before clinical detection of nasopharyngeal carcinoma, detection of EBV serum antibodies can be used as a screening indicator for nasopharyngeal carcinoma and can detect early stage nasopharyngeal carcinoma in the preclinical stage. Therefore, EBV-related tests should be included in the annual routine medical checkup. (4) It is recommended that screening for gastric cancer, including serum pepsinogen (PG), gastrin 17 (G-17) and Hp test, should be performed in the general population starting from the age of 40. If Hp (-) and atrophic gastritis (+), endoscopy should be performed once a year. In conclusion, the existence of viruses or bacteria is closely related to the occurrence of cancer, which reminds us that we should do a good job in prevention, timely treatment and early cancer screening to fight a prepared cancer prevention battle.