Preventing HPV

Posted on 17 August 2020

Most cases of cervical cancer can be prevented by implementing vaccination strategies and screening techniques to prevent against and identify human papilloma virus (HPV).

‘Cervical cancer screening is an essential part of a woman’s routine healthcare,’ says Dr Natalia Novikova, a gynaecologist at Mediclinic Cape Town. ‘Nearly all cases of cervical cancer are caused by infection with sexually transmitted, high-risk types of HPV. Most cases can be prevented if screening techniques and HPV vaccination strategies are implemented.’

As explained in a paper published in Continuing Medical Education, not all HPV types have the same ability to cause cancer. The 15 types with the highest risk are called oncogenic or high-risk HPV (hrHPV) types. The hrHPV types 16 and 18 account for more than 70% of cervical cancers worldwide. Low-risk HPV types (mainly HPV 6 and 11) cause genital warts, low-grade cervical dysplasias, and oral, laryngeal or conjunctival papillomas.

Current estimates show that 12 983 South African women are diagnosed with cervical cancer every year and 5 595 die from the disease. Cervical cancer ranks as the second most frequent cancer among women in South Africa and the most frequent cancer among women aged 15 to 44. About 3.2% of women in the general population are estimated to harbour cervical HPV-16/18 infection at any given time, and 64.2% of invasive cervical cancers are attributed to HPVs 16 or 18.

‘The primary goal of screening is to identify precancerous lesions caused by HPV so they can be removed to prevent invasive cancers from developing,’ says Dr Novikova. ‘A secondary goal is to find cervical cancers at an early stage when they can usually be treated successfully.’

For many years, cytology-based screening (a pap smear), was the only method of screening. This entails taking a scrape or sample of cells from the cervix and testing them for irregularities. These days, cervical cancer screening includes three approaches:

  1. HPV testing, which looks for the presence of high-risk HPV types in cervical cells
  2. Pap testing
  3. HPV/pap co-testing which checks the same cell sample for both high-risk HPV types and cervical cell changes.

‘Co-testing is widely available in America and women aged 30 to 65 years can have an HPV/pap co-test every five years,’ says Dr Novikova. According to a study conducted by researchers at Quest Diagnostics and the University of Pittsburgh Medical Center.

HPV/pap co-testing is more likely to find abnormal cells or cervical cancer than a pap test alone.

In South Africa, prevention begins with HPV vaccination of girls aged nine to 14 years old, before they become sexually active. Unfortunately, due to cost reasons, inoculations are not yet available to boys. Sexually active women up to age 26 can also be vaccinated.

There are two vaccines available:

* The first vaccine covers the most dangerous HPV strains 16 and 18.
* The second covers HPV strains 16 and 18 plus two other strains (Types 6 and 11 that cause genital warts).

The only way to avoid HPV entirely is never to be sexually active. Practically speaking, the HPV vaccine, together with regular pap tests, are your best defence against HPV and in many cases, cervical cancer.

 




Published in Gynaecology

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