Understanding HPV

Human Papillomavirus (HPV) is the main responsible of one of the most common sexually transmitted diseases worldwide and persistent infection is the major risk factor for the development of cervical cancer.

Nearly two decades ago, experts discovered a relationship between infection with HPV (human papillomavirus) and cervical cancer. Since then, they have learned much more about how HPV can lead to cervical cancer.

But what is HPV?

HPV, or human papillomavirus, is a virus that infects the skin and the cells lining body cavities. It is spread through close skin-to-skin contact. It is a very common infection which usually causes no symptoms at all.

Up to 8 out of 10 people will be infected with the virus at some point in their lives. HPV infections are usually on the fingers, hands, mouth and genitals. For most people, the infection will get better on its own and they will never know they had it. But in some people the infection will stay around for a long time and become persistent.

There are hundreds of different types of HPV. Most are harmless but around 15 types of HPV can cause cancer. These are called ‘high-risk’ types. People with persistent infections with ‘high-risk’ HPV types are those who are most likely to go on to develop cancer.

Some types of HPV are known to increase the risk of developing particular types of cancer and are known as high-risk HPVs. The types most often associated with cancer are types 16 and 18. High-risk HPVs can lead to abnormal changes in the cells, which is sometimes called dysplasia. Although dysplasia is not cancer, it's sometimes described as being pre-cancerous.

Other types of HPV can cause warts and verruca. These may appear on different parts of the body, but are more commonly seen on the hands and feet, in the genital area and around the anus. The types of HPV that cause visible warts and verruca are less clearly linked with cell changes that can increase the risk of cancer. They are known as low-risk HPVs.

“High-risk” types of HPV (HR)

There are more than a dozen types of "high-risk" HPV that can cause abnormal cells to form on the cervix. These abnormal cell changes may gradually develop into cervical cancer if not removed. The 13 types of high-risk HPV that are of most concern are known by the numbers 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73 and 82. Types 16 and 18 are the most dangerous, since they cause about 70 % of cervical cancers. In one study, the National Cancer Institute found that about 10 % of women with HPV type 16 or 18 developed advanced, pre-cancerous cervical disease within three years (compared to just 4 % of women with any type of HPV), and 20 % did so in 10 years (compared to 7 %).

“Low-risk” types of HPV (LR)

There are about 12 types of HPV that are called "low risk" because they cannot cause cervical cancer. They can, however, cause genital warts or very minor cell changes on the cervix. These low-risk types of HPV are known by the numbers 6, 11, 40, 42, 43, 44, 53, 54, 61, 66, 72, 81 and 89. Types 6 and 11 – which are linked to about 90 %of genital warts – are the most common.

and genotypes with “Probable high-risk” (PHR)

20, 26, 53, 66, 69, 70, 71 and 74

Keep in mind that of those infected with HPV, 50% of them will fortunately clear the virus within 8 months, 90% of them within 2 years. Therefore, it’s more likely than that if you have been infected sometime in the past, you either may have cleared the virus already or have acquired a non-cancerous strain.

In most countries, cervical screening using a Papanicolaou (Pap) test  is used to detect abnormal cells that may develop into cancer. If abnormal cells are found, women are invited to have a colposcopy. During a colposcopic inspection, biopsies can be taken and abnormal areas can be removed with a simple procedure.  Treating abnormal cells in this way can prevent them from developing into cervical cancer. 

The second type of test is the HPV DNA, which is relatively new and can be done during a Pap test with a gynaecologist. It involves taking a small sample of cervical cells with a cotton swab or a small brush.

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Since 99.7% of cervical cancers can be attributed to HPV, the importance of a simple HPV test from your gynaecologist cannot be overstated.

Tens of different Papillomavirus types infect humans, but only a handful are harmful. Mapping HPV types by genus (see Figure) reveals that certain species often cause similar warts and lesions, with most of the HPV types that cause cancer coming from the same species. However, shared pathology doesn't always indicate close family ties; HPV types 1, 2 and 4, which all cause common skin warts, are distant relations.