The Success Story of Vaccines: HPV and Cervical Cancer
Key statistics
Human papillomavirus (HPV) infection is now a well-established cause of cervical cancer and there is growing evidence of HPV being a relevant factor in other anogenital cancers (anus, vulva, vagina and penis) as well as head and neck cancers. Cervical cancer is the world’s fourth most frequent cancer in women, causing an estimated 570 000 new cases in 2018 and representing 7.5% of all female cancer deaths. In Malaysia, it is the third most prevalent cancer in women, ranked after breast and colon cancers.
Human Papillomavirus (HPV)
HPV is the most common sexually transmitted infection (STI). You can get HPV by having vaginal, anal, or oral sex with someone who has the virus. It is most commonly spread during vaginal or anal sex.
HPV can be passed even when an infected person has no signs or symptoms. Anyone who is sexually active can get HPV, even if you have had sex with only one person. You also can develop symptoms years after you have sex with someone who is infected. This makes it hard to know when you first became infected.
HPV is a different virus than HIV and HSV (herpes). There are more than 100 types of HPV, of which at least 14 can cause cancer, i.e. high-risk types. Among them, HPV 16 and 18 cause 70% of the cervical cancers and pre-cancerous cervical lesions.
While other HPVs such as HPV types 6 and 11 can cause genital warts. Genital warts usually appear as a small bump or group of bumps in the genital area. They can be small or large, raised or flat, or shaped like a cauliflower. Genital warts caused by HPVs are usually benign.
Image credit: Visual Science
How HPV causes cervical cancer?
When a person is infected with cancer-causing HPV, it can cause pre-cancerous lesions, which can be cleared up by the body most of the time. However, there is a risk that when this does not happen, the infection becomes chronic and the pre-cancerous lesions progress into cervical cancer.
This process usually takes 15 to 20 years for a woman to finally develop cervical cancer. Nonetheless, for those with weakened immune systems, such as those with untreated HIV infection, can take a shorter duration (5 to 10 years) to develop cervical cancer.
Image credit: Medical Device Network
HPV Vaccination
The most cost-effective public health measure against cervical cancer is HPV vaccination targets at girls aged 9-14 years old before they become sexually active. This is because HPV vaccines work best if administered prior to exposure to HPV. The vaccines cannot treat HPV infection or HPV-associated disease, such as cancer.
There are currently 3 vaccines protecting against both HPV 16 and 18, which are known to cause at least 70% of cervical cancers. The third vaccine protects against three additional cancer-causing HPV types, which cause a further 20% of cervical cancers. Two of the vaccines also protect against HPV types 6 and 11, which cause genital warts.
For 2019, HPV vaccination is FREE to Malaysian citizen or Permanent Resident (PR), female born in 1992-1996, single/not yet married, not pregnant and have not suffered from severe allergies that required treatment at a hospital. You may get the vaccination at any nearby Nur Sejahtera Clinics, LPPKN. Check out their website here.
Image credit: Fierce Pharma. Gardasil® is one of the few existing brands for HPV vaccines.
How successful HPV vaccination in preventing cervical cancer?
The short answer is: it’s pretty successful.
A systematic review and meta-analysis published in The Lancet studied 60 million individuals and up to 8 years of post-vaccination follow-up. The result is astounding: after 5-8 years of HPV vaccination, the prevalence of HPV 16 and 18 (i.e. the cancer-causing HPVs) decreased significantly by 83% among girls aged 13 - 19 years old and decreased significantly by 66% among women aged 20–24 years. Significant reduction is also seen in anogenital warts among boys and girls.
Is HPV vaccine completely safe?
Clinical trials and post-marketing surveillance have shown that HPV vaccines are very safe and very effective in preventing infections with HPV infections.
💡What is post-marketing surveillance?
Postmarketing surveillance (PMS) studies involve the systematic monitoring of medications while they are used in clinical practice. This is different from the controlled settings of premarketing clinical trials, in which study conditions are rigorously controlled. It is sufficed to say that if a drug or vaccine passed the post-marketing surveillance, it is safe to use.
Some of the side effects associated with HPV vaccination include nausea, vomiting, pain in the injection area, red and swelling at the injection area, headache, acne, weakness and tired muscles. However, these are mild and self-resolving side effects that should not be too worrying. The patient will be placed under observation for 20 minutes if these side effects are experienced.
In some extremely rare cases, the patient may experience severe allergies called anaphylactic shock. Symptoms of this include breathlessness and fainting. This is a medical emergency and referral must be made directly to the hospital. In addition, an estimated one case of ‘Guillain-Barre Syndrome’ (GBS) per 100,000 HPV vaccination may take place as well. In the event of the occurrence of GBS, occurring within 6 weeks after vaccination in which case will be found to have Acute Flaccid Paralysis (AFP) at the top of the foot. The cases of the suspected patient must be hospitalized and reported to the AFP surveillance system.
However, most people do not experience these extreme side effects and the benefits of getting HPV vaccination usually outweighs the risk. Discuss this with your doctor if you have any concerns.
Other important measures
Cervical cancer screening involves testing for pre-cancer and cancer among women who have no symptoms and may feel perfectly healthy. When screening detects pre-cancerous lesions, these can easily be treated, and cancer can be avoided. Screening can also detect cancer at an early stage and treatment has a high potential for cure.
As tobacco smoking is found to be one of the risk factors for cervical cancer, health education about tobacco use and smoking cessation services are crucial.
Condom promotion and provision for those who engaged in sexual activity are also important to reduce transmission of HPV.
World Immunization Week 2020 is an initiative by the World Health Organization (WHO) to promote the use of vaccines to protect people of all ages against disease. Read more about the campaign at https://www.who.int/news-room/campaigns/world-immunization-week/world-immunization-week-2020
DOC2US® would like to encourage everyone to take necessary immunizations and to prevent the preventable. #VaccineWorks
References:
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Cervical cancer. Accessed April 23, 2020. https://www.who.int/news-room/fact-sheets/detail/cervical-cancer
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Population-level impact and herd effects following the introduction of human papillomavirus vaccination programmes: updated systematic review and meta-analysis - The Lancet. Accessed April 23, 2020. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)30298-3/fulltext
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STD Facts - Human papillomavirus (HPV). Accessed April 23, 2020. https://www.cdc.gov/std/hpv/stdfact-hpv.htm
