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According to WHO data, 10-20 percent of the world is infected with HPV. people aged 15–49, including almost 40 percent. women under 25 years of age Women around the world also suffer from cervical cancer. Globally, this type of cancer is the second most common in women under 45 and the third most common death in women (after breast and lung cancer).
Cervical cancer is a disease of abnormal and uncontrolled growth of cells in the lining of the cervix. The main cause of cervical cancer is HPV infection. Contrary to popular belief, this type of cancer is not hereditary or genetically determined. Research conducted by prof. Harald zur Hausen proved that it is caused by certain types of human papillomavirus, or HPV for short. Prof. zur Hausen discovered that HPV DNA is incorporated into the DNA of cervical epithelial cells, where it may remain dormant for several or even several dozen years. Cells with such a changed DNA may become cancerous after many years. For this discovery, in 2008, Professor Harald zur Hausen was awarded the Nobel Prize in medicine and physiology, and his research enabled the creation of a prophylactic vaccine to protect against HPV infection and, consequently, its complications in the form of precancerous and cancerous changes in the cervix and other organs (e.g. anus, larynx). The human papillomavirus (HPV) infects only humans, both women and men – it does not attack any other organisms.
HPV – high risk of oncogenicity
As many as 200 HPV subtypes have been identified, of which 100 have been described, of which only a few are responsible for almost 100% of cervical cancer cases. These are primarily types 16 and 18, as well as 31, 33, 45 – viruses with a high oncogenic risk. They mainly infect cells of the mucous membranes and are responsible for over 70 percent. cases of cervical cancer, including – type 16 is responsible for more than half of all cases of squamous cell carcinoma, and type 18 – for approx. 55 percent. extremely difficult to detect cervical adenocarcinomas.
HPV is almost exclusively sexually transmitted. Population studies show that more than half of sexually active women are exposed to at least one type of HPV that causes genital infections. The problem is that in older women, infections more often go into the chronic phase and can turn into neoplastic changes.
Infection with oncogenic HPV virus and cancer development – the role of cofactors
Keep in mind that although HPV is very common, most infections are self-healing. Moreover, it usually takes years for an infection to develop into cancer. Regular Pap smears can usually detect abnormal cells early enough to develop. You can order the most modern and precise LBC liquid cytology with gynecological consultation at Medonet Market.
The primary cause of cervical cancer is persistent infection (i.e. for more than 6-12 months) caused by an oncogenic type of HPV. In many cases, it is accompanied by an additional contributing factor, called a cofactor. These include:
– smoking, because the substances contained in tobacco smoke suppress the immune response and have a direct carcinogenic effect,
– a large number of deliveries (over 7),
– long-term hormonal contraception,
– other sexually transmitted infections, incl. herpes infection, HIV, Chlamydia trachomatis, chronic inflammation,
– immunodeficiencies,
– deficiency of antioxidants in the diet,
– early sexual initiation,
– a large number of partners.
Body defense
HPV does not enter the host’s bloodstream immediately after infection as it does with other viruses, but infection is local. The body can fight most HPV infections on its own thanks to its immune mechanisms – it heals itself without leaving any permanent damage to the cells.
The body’s immunity can be both innate and acquired. Congenital, or non-specific, is genetically determined – a person is born with it. Its goal is, inter alia, destruction of microorganisms harmful to the body if they get into it. Cytokines (substances responsible for the regulation and type of immune response) as well as phagocytes (phagocytes, capable of absorbing and destroying organic substances such as bacteria or viruses) play an important role in it.
Acquired immunity, i.e. specific immunity, develops after contact with a specific pathogen – after being infected naturally or after vaccination. Its purpose is to prevent the development of an infection by recognizing and destroying specific pathogens. This is due to the existence of cellular immunity, the mechanism of which is the direct attack of leukocytes (white blood cells) on the microorganism, and humoral, consisting in the production of specific antibodies by lymphocytes that destroy the “intruder”.
We are infected with the HPV virus primarily through sexual contact. However, it can also be spread through direct skin-to-skin contact, such as with contaminated tissues of the labia, scrotum and anus. Therefore, a condom does not protect against HPV infection. It can also be carried on contaminated hands. Fortunately rarely, newborns are also infected from an infected mother during childbirth or nursing activities.
Only prophylaxis
Infection with oncogenic types of HPV in some women may be long-lasting and eventually lead to the development of cervical cancer. Even if this happens, the course of the disease is asymptomatic in the early stages. The infected cells may slowly develop into abnormal cells and then into cervical cancer cancer cells. This process can take years if changes are not detected in the early stages. That is why pap smear is so important to detect changes both in the early stages of infection and for a long time after exposure to the virus.
Pap smear and colposcopy allow for an early response and initiation of treatment.
It is worth knowing that there are no effective drugs against HPV infections. Only vaccinations protect against HPV infection specifically, especially since natural antibodies that arise in the body after an infection in the case of HPV do not protect against re-infection with the same type of HPV!
Two vaccines are licensed to prevent HPV infection – both provide protection against infection with oncogenic HPV types, ie 16 and 18 – intended for use in women 9-55 years of age. Vaccinations elicit a strong immune response that offers protection against possible infection. This is confirmed by the high effectiveness in clinical trials. One of the vaccines shows a specific cross-protection also against the other HPV types – 31 and 45, which are also oncogenic.
HPV vaccines, like other vaccines, can cause post-vaccination reactions: at the injection site (swelling, pain, redness) and systemic reactions (fatigue, headache and muscle pain, gastrointestinal disorders).
No HPV vaccine will cure already infected women, nor will it resolve pre-neoplastic and neoplastic lesions. Therefore, periodic cytological examinations should not be forgotten.
Substantive consultation: Paweł Grzesiowski, MD, PhD, head of the Department of Prevention of Infections and Hospital Infections at the National Medicines Institute in Warsaw.
Material prepared for the Quo vadis medcina workshop “Vaccinations as a pass to health” organized by the Association “Journalists for Health”, March 2010.