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Is it possible to get cervical cancer after the HPV vaccine?
Is it possible to get cervical cancer after the HPV vaccine? Female friends, vaccination + regular screening is the kingly way, Don’t take a chance!
Vaccination and cervical cancer screening are equally important!
A few days ago, my best friend sent a message to show me: “My 9-price HPV vaccine has been vaccinated! This lady no longer has to worry about getting cervical cancer in the future! It is a complete liberation!”
With the launch of 2, 4, and 9-valent HPV vaccines, some countries has ushered in an upsurge of HPV vaccination. Many women go for vaccinations. However, is it true that I can sit back and relax after receiving the HPV vaccine?
After vaccination, is there no need for screening?
HPV vaccine is the world’s first tumor vaccine, and its preventive effect on cervical cancer is obvious. The primary prevention of cervical cancer prevention and control strategy recommended by WHO is HPV vaccination and health education. ASCO also recommended HPV vaccination in 2017.
However, is there no need for cervical cancer screening after vaccination?
The answer is obviously no!
First of all, vaccination against HPV is necessary. The HPV vaccine can fundamentally block the transmission of HPV and is the most specific and effective preventive measure. Women aged <45, even if they are screened regularly, it is still necessary to receive HPV vaccine.
It should be noted that the HPV vaccine no longer has a protective effect on people who have been infected with the corresponding HPV and must be vaccinated before high-risk HPV infection.
In fact, the HPV vaccine does not prevent cervical cancer 100%.
Women who have sex, regardless of whether they have been vaccinated or not, need regular cervical cancer screening.
How to screen to prevent cervical cancer?
Knowing the importance of cervical cancer screening, how do we screen it?
On July 30, 2020, the American Cancer Society (ACS) formulated the latest cervical cancer screening and prevention guidelines. The guidelines are as follows:
Start screening age: 25 years old;
Women aged 25-65: First choice for HPV testing once every 5 years; if first-line HPV screening is not possible, HPV testing and cytology combined screening once every 5 years, or single cytology once every 3 years;
Women >65 years old: Stop any form of cervical cancer screening on the premise that there is no history of cervical dysplasia II+ (CIN II+) in the past 25 years, and negative screening results are recorded in the 10 years before the age of 65 check;
Women after hysterectomy, who have no cervix and have no CIN II+ lesions in the past 25 years, should not be screened;
Women who are vaccinated with HPV are screened in the same way as women who are not vaccinated.
3 problems facing cervical cancer screening
1. Performing colposcopy, biopsy, etc. may cause reproductive problems in women, especially premature delivery;
2. Clinical operations such as colposcopy, biopsy and treatment will cause discomfort to women’s body;
3. False positive results from cervical cancer screening can cause women’s anxiety.
Five issues to pay attention to after HPV vaccination
Question 1: Impact on HPV testing
HPV vaccine cannot cover all high-risk HPV subtypes, and the distribution of HPV subtypes in vaccinated women is different from that of women who have not been vaccinated.
Studies have shown that during natural infections, there may be competition among many different types of HPV. Even if vaccinated, certain HPV subtypes are eliminated, and other HPV subtypes may occupy their ecological locus.
Vaccinated women can be immune to high-risk HPV subtypes, and the proportion of cervical cancer caused by infections other than the HPV subtypes covered by the vaccine may increase.
Among women who have been vaccinated against HPV, the proportion of women with non-HPV16 and 18 infections in the total number of women with low-grade cytological abnormalities has increased significantly.
Therefore, the problem of vaccinated HPV-positive population is facing severe challenges. The HPV16 and 18 diversion strategies need to be reassessed, and whether there is a more reasonable diversion method needs further study.
Question 2: It may reduce the positive rate of cytology
Gertig et al. found that compared with unvaccinated women, the number of high-grade cytology smears in vaccinated women was significantly reduced. Palmer et al. showed that in women who were fully vaccinated, the results of all types of abnormal cytology were significantly reduced.
These studies show that when cytology is used, cytology technicians will face more and more normal cytology smears, the false negative rate of cytology will increase, and the positive predictive value of cytology in cervical screening will decrease.
Question 3: Type limitation of HPV vaccine
The HPV vaccines that have been marketed do not cover all known high-risk types of HPV, although global large sample analysis data shows that about 70% of cervical cancers are caused by HPV16 and 18, and 90% of cervical cancers are caused by 7 high-risk types of HPV.
The effectiveness of the 9-valent vaccine in preventing cervical cancer can reach 90%, but because it cannot cover all subtypes, it cannot achieve a 100% preventive effect.
In addition, the distribution of HPV subtypes is highly regional. HPV16 and 18 are the HPV subtypes with the highest carcinogenicity rate in some countries, but there are also HPV52 and 58 subtypes, especially the HPV52 subtype has an infection rate that exceeds the HPV16 subtype in some areas of some countries. Therefore, there may be regional differences in the effect of HPV vaccine on the incidence of cervical cancer.
Question 4: The preventive effect of HPV vaccine is uncertain
Many precancerous lesions will not progress to cancer or even self-heal, so it is uncertain whether existing vaccines are really effective in preventing cervical cancer.
Question 5: The effective time of HPV vaccine is uncertain
The effective time of the vaccine has not yet been determined. Even if the effective period of the vaccine is predicted to be 20 years according to the model, if three doses of vaccination are completed at the recommended age (11-12 years), the protection period of the vaccine is only 31-32 years old.
Although cervical cancer has been getting younger in recent years, the age of 40-60 is still the main high-incidence period.
Therefore, whether it is necessary to optimize the vaccination process and boost immunization at a specific time period still needs to be further explored.
In short, HPV vaccination “contains” cervical cancer from the source, effectively reduces the incidence of cervical cancer, and is an effective way for women to prevent cervical cancer.
However, existing HPV vaccines cannot eliminate existing HPV infections or cover all carcinogenic types. Screening is still the main method to prevent cervical cancer. The combination of vaccine and screening can more effectively reduce the risk of cervical cancer in women.
Female friends, vaccination + regular screening is the kingly way, don’t take a fluke!
(source:internet, reference only)