2023-06-13 16:59:37
Science doesn’t know exactly what causes most cancers, but several factors have been linked to a higher risk of developing cancer, such as lifestyle (eg smoking), for some specific types of cancer the heredity (for example a history of breast cancer in the family) and sometimes a virus can be a triggering factor.
Cancer occurs when a cell in our body undergoes a modification of its DNA, more precisely of the genes that control cell division (proto-oncogenes), which, in the case of cancer, are overstimulated, and this cell “escapes” to our immune defense system or proliferates faster than it can contain it.
Relationship between viruses and cancer
Viruses are responsible for 10-15% of cancer cases worldwide. But it’s not just any virus that can lead to cancer, it’s only some that affect specific types of cells in our body, and when they incorporate a virus into human DNA or the cellular environment , generate genomic instability, which in turn leads to biochemical instabilities that can lead a normal cell to become a cancerous cell, this is what clinical oncologist Dr. Ângelo Fêde explains in an interview for Creapharma (and Criasaude.com.br – Brazilian version of Creapharma.ch) dating from May 2023. Even during infections with these specific viruses, there are few cases where cancer develops, underlines Dr. Ângelo Fêde.
How can viruses cause cancer?
Three different pathways by which a virus can cause cancer are currently known.
1. Induction of chronic inflammation (eg, liver cancer caused by hepatitis B or C virus).
2. Suppression of the immune system (for example, the HIV virus).
3. Genetic alteration – proton-oncogene in an oncogene (eg uterine and colon cancer caused by HPV virus).
Cancer-related viruses
Most viruses, such as those that infect the cells of the respiratory system (eg influenza viruses), are not risk factors for cancer because they only stay in our body for a short time and the defense cells of our body can quickly destroy the few cells damaged by the virus.
There are 8 viruses linked to the onset of cancer, here they are:
1. Human papillomavirus (HPV)
The human papillomavirus (HPV in English, for human papillomavirus) can infect the skin and mucous membranes, causing genital warts and, in more severe cases, cancers of the cervix, penis, anus, vagina, vulva, oropharynx or from the mouth. Although HPV is very common, most people infected with the virus do not develop cancer. There are over 150 subtypes of this virus and only 12 are linked to the development of cancer. However, women who have persistent HPV infections have an increased risk of developing cervical cancer.
HPV is transmitted through sex and most people with an active sex life will get an HPV infection at least once in their lifetime.
In many countries, there is a vaccine for people aged 9 to 14 that protects once morest four HPV subtypes. However, vaccination is also beneficial in adulthood (up to age 45), except that it requires 3 doses instead of 2. In some countries there is a new HPV vaccine that works once morest 9 HPV subtypes.
In addition to vaccination, other forms of prevention include:
– detection examinations (cytological, also known as smears) from the age of 25 for people with a uterus;
– control and treatment of lesions when they exist;
– the use of condoms.
2. and 3. Hepatitis B virus (HBV) and hepatitis C virus (HCV)
HBV and HCV are transmitted by contact with an infected person’s blood, saliva, semen or vaginal secretions or perinatally (during pregnancy). HBV and HCV primarily infect liver cells and can cause liver damage such as cirrhosis, which in turn can lead to liver cancer. They are considered indirect carcinogens due to the chronic inflammation and cell damage they cause.
Vaccination once morest hepatitis B, in three doses, is one of the main ways to prevent infection with the virus. Most people clear HBV spontaneously, but once a person has symptoms, the disease becomes chronic and treatment must be lifelong.
In the case of HCV, there is no vaccination, but there are treatments that can cure even the chronic form of the disease.
4. The Epstein-Barr virus (in English: Epstein-Barr or EBV)
Responsible for mononucleosis (“kissing disease”), EBV is widespread in the population, in particular because of its mode of transmission through direct contact with infected saliva, objects and blood.
Once a person is infected, they carry the virus for life, but most of the time without causing any health problems.
Although rare, affecting mostly immunocompromised people, EBV can infect B lymphocytes and epithelial cells, causing half of cases of Hodgkin’s and Burkitt’s lymphomas, and can also lead to nasopharyngeal and stomach cancers .
The main form of prevention is to avoid contact with people showing symptoms, not to share cutlery or glasses.
5. Human herpes virus type 8 (HHV-8)
HHV-8 is a virus that can cause Kaposi’s sarcoma, a type of cancer that affects the skin and internal organs, especially in people with weakened immune systems (eg AIDS). However, most infected people do not develop cancer.
HHV-8 is transmitted primarily through saliva, but it can also be transmitted through sexual contact and through blood.
The main form of prevention is to avoid sharing utensils and syringes and to use condoms.
6. HTLV-1 virus (Human T-cell leukemia/lymphoma virus)
HTLV-1 is a virus that is transmitted through contact with infected blood, unprotected sex, or breastfeeding. The virus can lead to leukemia and T-cell lymphoma. It is widespread in areas of the world where the virus is endemic, such as Japan, Africa and the Caribbean.
Most people infected with this virus do not develop cancer. Infection is prevented by using condoms and not sharing needles.
7. Merkel cell polyomavirus
Called in English Mekel cell polyomavirus (MCPyV) is the virus that causes Merkel cell carcinoma, a rare and aggressive skin cancer that tends to affect older white people. As it is linked to exposure to UV rays, its prevention consists in limiting exposure: avoiding the sun at times when UV rays are strongest, wearing protective clothing, using photoprotectors with a sun protection filter ( FPS) of at least 30.
8. Human Immunodeficiency Virus (HIV)
Although HIV (human immunodeficiency virus) infection is a major risk factor for several cancers, especially cancers associated with other infections, the way this virus increases the chances of developing cancer is by suppressing the immune system of the infected person. Other forms of immunosuppression carry the same cancer risk as HIV.
General cancer prevention tips:
– Maintain healthy habits (moderate diet and physical exercise);
– Avoid smoking (for those who smoke, seek medical support to quit);
– Use condoms (in case of sexual life outside a faithful relationship);
– Get vaccinated;
– In case of injury or suspicion of illness, consult a doctor and seek treatment as soon as possible.
June 13, 2023. By Adriana Sumi (pharmacist). Exclusive content. Original news in Portuguese published ici. Control and final supervision: Xavier Gruffat (pharmacist). Photo credits: Adobe Stock.
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