[Fat Bear Science] This is the only cancer with a clear cause. This measure can achieve more than 90% prevention. The sooner the better!

Cervical cancer is a malignant tumor that grows in the female cervix. It is the only malignant tumor with a clear etiology. Cervical cancer is a disease caused by persistent infection of the human papillomavirus (HPV) in the female reproductive tract. Relevant studies have shown that HPV can be detected in about 98% of cervical cancers. More than 90% of cervical cancers in Chinese women are caused by high-risk HPV. The HPV infection rate in my country is distributed in a "bimodal" manner by age, with the first peak at 15-24 years old and the second peak at 40-44 years old.

It can be said that HPV and cervical cancer have an inseparable relationship. At the 2022 city-wide health and health work teleconference held by the Chongqing Municipal Health Commission, Chongqing will launch free HPV vaccination for girls of appropriate age in 2022.

March 5, 2022 is the fifth "International HPV Awareness Day", and this year's publicity theme is "Let the world worry less". In order to better contribute to China's efforts in eliminating cervical cancer, let the public understand the disease, prevent the disease, and let patients treat the disease in a standardized manner. Co-organized by the Peking Union Medical College Education Foundation, Peking Union Medical College School of Mass Medicine and Public Health, Chinese Academy of Medical Sciences Cancer Hospital, Chongqing University Affiliated Cancer Hospital and other units, the "Fifth International HPV Awareness Day" related activities were carried out simultaneously in various cities across the country.

The Affiliated Cancer Hospital of Chongqing University will work with the School of Public Health and Management of Chongqing Medical University to provide health education to college students and the public through a series of activities such as lectures, distribution of brochures, prize-winning quizzes on cervical cancer-related knowledge, and free clinics.

Today, let us learn about HPV and cervical cancer.

What is HPV virus?

HPV, known as human papillomavirus, is a DNA virus that reproduces by living in human cells. As a disease that easily infects the epidermis and mucosal squamous epithelium of the human body, HPV is mainly transmitted through sex, entering the reproductive tract, mouth or throat, thereby causing mucosal skin infection. It is also possible to be infected through direct contact. For example, if the hands touch HPV-contaminated items, the virus may be brought into the reproductive organs when going to the toilet or bathing, or the reproductive organs may come into contact with underwear, etc., which may also cause infection. In short, HPV is highly contagious.

HPV infection is not easy to detect, and many people are infected without knowing it. Almost all cases of cervical cancer are related to HPV infection. HPV viruses can be divided into carcinogenic (high-risk) and non-carcinogenic (low-risk). The most common high-risk types are HPV16 and HPV18. About 55% to 60% of the causes of cervical cancer are related to HPV16. HPV18 is second in carcinogenicity and is associated with 10% to 15% of cervical cancer. More than 90% of cervical cancers are related to persistent infection with these two high-risk HPV types.

Will I get cervical cancer if I am infected with HPV?

No. Being infected with HPV does not necessarily mean you will get cervical cancer. There are more than 200 genotypes of HPV viruses discovered so far, and only a small number of women infected with high-risk HPV will eventually develop cervical cancer.

It is worth noting that most cervical cancers are caused by HPV virus, and they are persistent infections of high-risk HPV virus, but this does not mean that most people infected with HPV will develop cervical cancer. In fact, HPV infection is an extremely common viral infection, just like our daily cold. The probability of HPV infection in a woman's lifetime is as high as 85%-90%. All women who have sex may bring HPV virus into the reproductive tract through sexual contact.

It usually takes more than 10 years from HPV infection to cancer. After HPV infection, it can be cleared by the body's immune mechanism within a few months to one or two years, so most HPV infections are transient and have no clinical symptoms.

In addition to cervical cancer, HPV virus can cause genital warts and penile cancer. Therefore, men can also choose to get HPV vaccine. However, considering many factors, most countries including my country and the World Health Organization have not yet recommended male vaccination.

Why is it recommended that women of appropriate age receive HPV vaccination as early as possible?

This is because the earlier you get the HPV vaccine, the better the protection. As I just said, the main cause of cervical cancer is persistent HPV infection, which is mainly transmitted through sex. Early sexual intercourse is the main behavioral factor causing persistent or repeated infection. This is related to the behavioral and physiological characteristics of adolescence. During adolescence, a large number of rapidly proliferating transitional squamous cells, glandular cells, and metaplastic cells form at the external cervical opening, which are conducive to HPV parasitism and replication.

The research results show that if the vaccine is administered at the age of 16 to 18, the effectiveness of preventing cervical cancer is 34%, and the effectiveness of preventing severe cervical intraepithelial neoplasia is 39%; if the vaccine is administered at the age of 12 to 13, these two figures are as high as 87% and 97% respectively.

The instructions for the domestically produced bivalent HPV vaccine clearly stipulate that girls aged 9 to 14 should receive two doses of HPV vaccine. Many studies have found that two doses of HPV vaccine for girls aged 9 to 14 can achieve the same immune effect as three doses for girls aged 15 and above.

However, the HPV vaccine is not based on whether or not you have had sex, nor is it only suitable for women in younger age groups. Women in the following age groups can better protect themselves.

The appropriate ages for the three vaccines currently approved by my country's CFDA are as follows:

* Bivalent vaccine (prevents HPV types: 16/18): females aged 9 to 45 years;

* Quadrivalent vaccine (prevents HPV types: 6/11/16/18): females aged 9 to 45 years;

* Nine-valent vaccine (prevents HPV types: 6/11/16/18/31/33/45/52/58): females aged 16 to 26

Which groups of people should not receive HPV vaccine?

1. Acute phase of severe immunodeficiency disease. Immunosuppression is not a contraindication for HPV vaccination, but if the immune function is low, the immune response is poor. Therefore, vaccination can be performed during the non-acute phase of immunosuppressant use.

2. Vaccination should not be given during the acute phase of moderate or severe illness, or during a cold or fever with severe infection.

3. It is contraindicated for those who are allergic to protein or yeast.

4. Pregnant women.

Does getting the HPV vaccine mean that you will not get cervical cancer?

No. Although HPV16 and HPV18 are the main high-risk types, they cannot completely cover all HPV viruses. There are three types of HPV vaccines on the market worldwide. The nine-valent vaccine has the widest coverage and can prevent 90% of HPV viruses that cause cervical cancer, but it cannot completely cover all subtypes of the virus.

At the same time, the medical community still believes that more than 90% of cervical cancer is caused by HPV infection, and some cervical cancer may be caused by other factors. Therefore, even if you have received the HPV vaccine, female compatriots should follow the regular cervical cancer screening strategy and undergo regular cervical cancer screening.

When irregular vaginal bleeding or bleeding after sexual intercourse occurs, vaginal discharge is characterized by increased leucorrhea, or serous, purulent, rice-water-like, bloody and foul-smelling leucorrhea, or persistent lumbar or sciatica pain, women should be screened and treated early.

HPV vaccination is the primary prevention of cervical cancer, that is, the cause of disease prevention. But there is also a very good secondary prevention measure, that is, cervical cancer screening. Including cervical cytology examination and HPV testing, through regular and effective screening, late-stage cervical cancer can be completely eliminated.

Is the HPV vaccine effective for life?

Not necessarily. The HPV vaccine is just a preventive measure, but it does not mean that women who have received the vaccine will not need to undergo cervical cancer screening in the future. There is still a lot of uncertainty as to whether the HPV vaccine can maintain its protective effect for life. Related studies have 14 years of statistical data, showing that the protective effect does not weaken over time. The 14-year data is mainly because the vaccine has been on the market for a limited time. Whether it has a longer protection period or even lifelong effectiveness can only be answered by time.

What are the side effects or adverse reactions after HPV vaccination?

Pain, redness or swelling at the injection site; fever (usually below 38°C); headache or fatigue; mild nausea; vomiting; muscle or joint pain may occur. The above symptoms are mild. Urticaria is less common, and in severe cases, there is local edema and blisters.

A small number of people have adverse reactions after vaccination, such as hypersensitivity reactions, and subsequent vaccinations need to be cautious or terminated. However, some cases reported abroad about HPV vaccine side effects causing serious consequences such as paralysis are rare phenomena.

Expert Profile

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Zhou Qi

Discipline leader of the Gynecologic Oncology Center of the Affiliated Cancer Hospital of Chongqing University, chief physician, second-level professor, and doctoral supervisor.

The chief expert on cervical cancer, he is good at the diagnosis and treatment of benign and malignant gynecological tumors, surgery/chemotherapy/radiotherapy of gynecological malignant tumors such as cervical cancer and ovarian cancer, and the treatment of difficult and critical tumor diseases. He has high attainments in the early diagnosis and treatment of malignant tumors, treatment of precancerous lesions and tumor immunotherapy.

Clinic hours: All day on Monday (special outpatient clinic)

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Li Yucong

Deputy Chief Physician of Gynecological Oncology Center, Affiliated Cancer Hospital of Chongqing University, Doctor of Medicine.

She is good at comprehensive treatment of benign and malignant gynecological tumors, open abdominal and minimally invasive surgeries for cervical cancer, endometrial cancer, ovarian cancer, etc. She is especially good at the overall management and individualized treatment of cervical cancer and precancerous lesions.

Clinic hours: Tuesday afternoon, Thursday afternoon

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Text/Fat Bear

Review/Zhou Qi and Li Yucong

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Science Popularization China Co-construction Base

Chongqing Science Popularization Base/Chongqing Health Promotion Hospital

Chongqing Science and Technology Communication and Popularization Project

Chongqing Grassroots Science Popularization Action Plan Project

National Health Commission National Basic Public Health Service Health Literacy Project