HPV infection, prevention and cervical cancer and precancerous lesions 1.What is HPV? HPV is the abbreviation of Human papilomas virus (HPV). 1974, Dr. Hausen, a German virologist, proposed that the occurrence of cervical cancer is related to HPV infection, so the major discovery that the Nobel Prize in Medicine was awarded to Dr. Hausen in 2008. 2. Types and subtypes of HPV More than 100 subtypes of HPV have been identified. HPV belongs to the family of multiviruses and is a cyclic double-stranded DNA virus. HPV can be divided into skin and mucosal groups according to their tissue heterophilicity. Within the mucosal group, it is further divided into low-risk and high-risk types based on their association with cervical cancer. The pathogenicity of different subtypes of HPV to cervical epithelium varies, with HPV.16, 18, 31, 33, 35 and 45 being high-risk types associated with high-grade CIN and cervical cancer, and HPV.6, 11, 34, 42, 43 and 44 being low-risk types associated with low-grade CIN and genital warts. The majority of the current literature reports that CIN I is mainly associated with HPV 6, 11, 31 and 35, while CIN 1I and CINIII are mainly associated with HPV 16, 18 and 33. The most common HPV types in cervical cancer are HPV16 and 18. 3. Relationship between HPV infection and cervical precancer and cervical cancer Less than 4% of normal women are infected with HPV. The detection rates in patients with CIN grade I, II and III are 30%, 55% and 65% respectively, while in cervical cancer the infection rate is basically 100%, and the higher the CIN grade, the higher the HPV infection rate. In a study of 8,000 women tested for HPV DNA, it was found that 28% of the group tested positive for HPV DNA developed CIN 1I or CINIII within 2 years, while only 3% of the negative group developed CIN I or CIN 1I. genital tract infection with high-risk HPV is a major factor in the high incidence of cervical cancer and CIN, and 100% of patients with cervical cancer were positive for high-risk HPV infection. About 97% of CIN grade II and CIN grade llI are positive. HPV DNA is mainly present in free form in benign lesions. A prospective study by Dalstein et al. showed that women with recurrent HPV infection have an increased risk of developing CIN grade II and III. A prospective study by Dalstein et al. showed that women with recurrent HPV infection had an increased risk of developing CIN grade II and III. None of the women with persistent HPV negative or transient HPV infection progressed to CIN grade II or III during follow-up. Persistent HPV infection plays an important role in the development of cervical lesions. It indicates that when HPV reproduction stops at a certain phase of the replication cycle, this persistent or recurrent HPV (especially high-risk types) infection may lead to cellular transformation to a malignant phenotype, which greatly increases the risk of developing cervical carcinoma in situ. 4. HPV infection and progression of cervical lesions In women with HPV infection, the degree of cervical lesions increases with increasing viral load. moberg et al. concluded that high viral load increases the occurrence of HPV viral integration events and therefore, the risk of progression to invasive cancer increases with increasing viral load. This may also be one of the reasons why the viral load is also higher in those with high-grade lesions.HPV infection outcome One study reported that the prevalence of HPV infection among 608 female college students was 43%. The average duration of HPV infection is 8 to 14 months. In more than 90% of cases, the infection resolves within 2 years. About 1 percent of infected women develop external genital warts, and 5 percent or 10 percent develop CIN. Since the vast majority of women with HPV infection do not develop malignancy, it is suggested that a single HPV infection may not be sufficient to cause cancer and that other factors should play an important role. Studies have suggested that the main factors affecting the regression of HPV infection include internal factors, individual immune status, and external factors such as the subtype of HPV infection, duration of infection, and other factors such as smoking and sexual behavior of male partners. After high-risk HPV infection. A large number of viruses keep replicating. The combination of self and external factors will eventually lead to cervical precancer and cancer. Therefore, it is especially important to strengthen the follow-up of HPV-infected women, relieve their mental fear, improve their own immunity and eliminate other high-risk factors, and monitor HPV and cervical exfoliation cell examination. 5. How is HPV infected? The most important way of infection is through sexual intercourse. 6.Will I get cervical cancer if I am infected with HPV? It is generally believed that high-risk HPV is associated with the development of cervical cancer and low-risk HPV is associated with benign lesions of the reproductive tract. In fact, 70-80% of women have been infected with HPV during their lifetime, and most of them clear it by themselves within 1-2 years after infection through their own immunity. To borrow the words of Professor Liao Qinping from the Department of Obstetrics and Gynecology at Peking University First Hospital, “HPV infection in women is as common as having the flu”. Therefore, even if HPV infection is detected, there is no need to be nervous. Only persistent infection with high-risk HPV is associated with the risk of cervical cancer. Even in the case of high-risk HPV, its toxicity (carcinogenicity) also varies from strong to weak. Therefore, regular HPV testing, especially HPV type testing, is very important to predict the risk of cervical cancer and has important clinical guidance. 7.When should HPV screening start? Due to the special nature of reproductive structure, all women who have sex may bring HPV into the reproductive tract through sexual contact. Just like a cold and fever, this is a common occurrence. However, most women are able to destroy the HPV virus that enters their bodies through their own immunity, and the infection is only transient. Only a few women with weakened immune system are unable to destroy the HPV that enters their body, resulting in persistent HPV infection, before it may develop into cervical cancer, a process that also takes about 8 to 12 years. Therefore, women who are sexually active should have regular cervical cytology examinations (such as cervical smear or thin layer liquid-based cytology) on the one hand, and HPV-DNA tests should be started after the age of 30 on the other hand. If the test result is negative, it means that they are not infected by HPV, so they will not be at risk of cervical cancer for a long time, and it is recommended to do this test again every two to three years. cervical cells. If there is no abnormality, it is recommended to review the test every year, and once abnormalities are found, timely treatment can be carried out to nip cervical cancer in the bud. 8. What should I do if I am positive for HPV? If there is only HPV infection, no abnormalities in TCT and colposcopy, and no cervical lesions, we usually take the follow up approach. At present, for the treatment of HPV infection, on the one hand we can use anti-viral medication, and on the other hand we have to improve our own immunity. There are many ways to improve immunity, one is to rely on drugs, such as interferon; in addition, we should pay attention to diet, strengthen physical exercise, and maintain a regular life. In short, we should keep the right attitude towards HPV infection, neither let it go, nor be too panic. HPV infection is most common in young and sexually active people, and the risk of cervical cancer is more than twice as high for those who have their first sexual intercourse less than 18 years old as for those who are 20 years old. The average duration of HPV infection in young women is 8 months, with 30% remaining infected after 1 year and 9% after 2 years. The high incidence of cervical cancer in early marriages is most likely related to early infection with the virus and possibly the synergistic effect of other cofactors, which leads to cancer of the normal cervix. As young women are sexually active, their immune systems are not sensitized and are susceptible to HPV infection, and those with persistent HPV infection are likely to develop abnormal cytological patterns. there is a close causal relationship between HPV infection and cervical cancer prevalence, and most foreign literature reports that the HPV positivity rate of cervical cancer specimens tested by PCR technique is 70% to 99%, and the HPV infection rate is significantly higher in young patients than in older ones. Such a high rate of HPV infection in young women is a very important factor in the rejuvenation of cervical cancer, and it is extremely important to explore the relationship between HPV and young cervical cancer.