Understanding HPV and cervical screening

Cervical cancer is the fourth most prevalent form of cancer among women worldwide; in 2018 an estimated 570 000 women were diagnosed with cervical cancer and it was responsible for the death of 300 000 women worldwide, with almost 90% of the deaths occurring in low and middle income countries (World Health Organization, 2020a). In the UK, cervical cancer is the 14th most common form of cancer in women: around 3200 women each year are diagnosed with cervical cancer, which equates to over 8 new diagnoses each day (Cancer Research UK, 2020). The World Health Organization estimates that without any action being taken, incidence rates will increase, with new cases of cervical cancer rising to 700 000 and the number of deaths rising to 400 000 by 2030. However, cervical cancer is a preventable disease and is curable if detected early and managed effectively. The National Cervical Screening Programme has been in force in the UK since 1988 and is estimated to have saved 5000 lives each year (Stubbs, 2018) and the introduction of the human papillomavirus (HPV) vaccination in 2008 in the UK has been a further significant step in preventing cervical cancer. A recent study by Falcaro et al (2021) suggests the HPV vaccine is reducing cases of cervical cancer by almost 90% in England. Another study showed both a reduction in pre-cancerous growths and an 87% reduction in cervical cancer (Gallagher, 2021). The World Health Organization (2020a) have recently launched a Global Strategy to Accelerate the Elimination of Cervical Cancer. It identifies three key steps: vaccination; screening; and treatment. While it is acknowledged that vaccine uptake is relatively good in the UK, with almost 84% coverage in females completing a 2-dose schedule in 2018/2019 (Public Health England, 2020a), the estimated number of eligible women who attend for regular cervical screening remains low, with only 70.9% of eligible women aged 25–49 years and 76.4% of eligible women aged 50–64 years attending cervical screening as of March 2020 (Public Health England, 2021). The number of completed vaccination schedules and attendance for cervical screening are expected to be lower following the COVID-19 pandemic with school closures and the reduction in face-to-face appointments at GP surgeries during the national lockdown (Public Health England, 2021; NHS Digital, 2021). It is essential that this downturn is reversed both in terms of vaccination and cervical screening as we move towards the Global Strategy to Accelerate the Elimination of Cervical Cancer (WHO, 2020a).

From December 2019, the cervical screening process was changed in England, Scotland and Wales: this involved transitioning from a cytology based test to HPV primary screening in primary care (Stubbs, 2018); Public Health England, 2020b). For all health professionals working in general practice, and specifically those undertaking cervical screening, it is essential that they have a sound knowledge base of what HPV is, how common it is, how it can increase the risk of cervical cancer developing and what the results of primary screening mean and how the risk of HPV can be reduced.

What is HPV?

HPV is a group of viruses that most sexually active people come into contact with during their lifetime: it is estimated approximately 8 in 10 people will be infected with HPV at some point in their lives (Cancer Research UK, 2020a). There are over 100 different types of HPV that are categorised as low- or high-risk (UK Health Security Agency, 2019). At least 14 types of HPV are cancer-causing and these are known as high-risk HPV types (WHO, 2020b). These can cause cancer of the vagina, vulva, penis and anus; however, these cancer types are less common than cervical cancer. High-risk types 16 and 18 are responsible for more than 70% of cervical cancers and pre-cancerous cervical lesions worldwide (WHO, 2020b). HPV has been detected in more than 99.7% of cervical cancers (Jo's Trust, 2018; WHO, 2020). It is estimated that 80% of sexually active adults will become infected during their lifetime, with the peak time for contracting the infection shortly after they have become sexually active (WHO, 2020b). HPV is sexually transmitted; however, it is worth noting that penetrative sex is not required for transmission, skin-to-skin genital contact can also lead to transmission of the virus. For most individuals, the body's immune system will naturally clear the HPV infection within 2 years; however, for a small number, the immune system will not be able to effectively clear this virus. This leads to a persistent infection which causes the epithelial cells of the cervix to change (Jo's Trust, 2018). However, this change in cells does not always result in cervical cancer, as screening can identify these changes early which can be monitored and treated effectively. If not treated effectively, these pre-cancerous lesions can progress to invasive cervical cancer (WHO, 2020b). Other types of HPV virus are identified as non-cancerous and are identified as low-risk: types 6 and 11, especially, are responsible for 90% of genital warts.

HPV sampling

Although the screening process has changed from cytology to HPV primary screening, the training requirements for cervical screeners remain the same. Trainee cervical screeners are required to complete a minimum of 12 hours initial training, this must include at least 3 hours of practical training, where the trainee can practice their technique on a pelvic model. Trainees are supported in their practice by a trained cervical screening mentor, who will undertake an interim assessment which the trainee must complete satisfactorily before starting their unsupervised samples. Trainees must take 20 acceptable samples before undertaking a final clinical assessment (Public Health England, 2020c).

With the introduction of HPV screening, cervical screening laboratories no longer provide feedback to trainees on their transformation zone (TZ) sampling. This quality marker was previously used to assess that trainees and trained cervical cytology takers where accurately sampling the cervix to retrieve adequate cells to perform a cytology test on. Due to the move to primary HPV screening this is no longer required as a quality marker; however, all trainees and trained cervical screeners will receive feedback on their sample acceptance.

Results of screening

With the launch of HPV primary screening, it is essential health professionals are able to explain the results and the significance of these to their patients. Patients will usually receive their screening results in the post; however, a number of patients may contact the surgery to ask for further explanation or information. Some patients may see a positive HPV result as a cancer diagnosis (American Cancer Society, 2020), and while a positive HPV test does require a cervical cytology test (which will be conducted on the same sample), a positive HPV test on its own does not indicate cervical cancer, as the changed cells often revert to normal by themselves (Cancer Research UK, 2020b). Please see Table 1 for a further explanation of cervical screening results.

How to reduce the risk of high-risk HPV

Once an individual is sexually active, they are at risk of HPV. However, there are measures that individuals can take to reduce the risk. Cervical screening is a key intervention in reducing the risk of high-risk HPV developing into cervical cancer. The HPV vaccine is also a safe and effective intervention in the prevention of HPV infection and associated cancers (Sisson and Wilkinson, 2019; WHO, 2020b). In excess of 280 million doses of the vaccine have been given worldwide, with over 10 million of those given in the UK. In the UK the HPV vaccine programme has been offered to all girls aged 12 or 13, since 2008 and this has been widened to include boys aged 12 or 13 since 2019 (UK Health Security Agency, 2021). The vaccine is given intramuscularly into the arm and 2 doses are required, usually 6–12 months apart. To provide the best protection the vaccine should ideally be given before individuals are sexually active, hence the age the vaccination is offered. If an individual is sexually active then they should still have the vaccination (UK Health Security Agency, 2021). In the UK, people are eligible to receive the vaccination up to the age of 25. While it is estimated that the vaccination will prevent up to 90% of cervical cancer cases, it is important that people who have a cervix and are fully vaccinated attend regular routine cervical screening when invited (Falcaro et al, 2021; UK Health Security Agency, 2021).

Although approximately 80% of individuals will contract HPV within their lifetime, there are other factors that can increase the risk of developing HPV persistence and the potential development of cervical cancer. These include having a weakened immune system, having multiple sexual partners and co-infection with other sexually transmitted infections, parity and being of a young age at first birth, and smoking (WHO, 2020b). Individuals with HIV – which affects the immune system – are more likely to have persistent HPV infections which leads to a more rapid progression to pre-cancerous and cancerous lesions. For individuals with normal immune systems, it takes 15–20 years for cervical cancer to develop compared to just 5–10 years for those with weakened immune systems, such as those with HIV. Individuals with HIV are six times more likely to develop cervical cancer compared to individuals without HIV. Therefore, individuals with HIV are recommended to have more regular cervical screening, which should be performed annually (WHO, 2020a). Cigarette smoking increases the risk of HPV infection: if a person smokes, they are estimated to be twice as likely to get HPV or develop an HPV-related cancer as a non-smoker (Mzarico et al, 2015; Sugawara et al, 2019). It is unclear as to the exact way that smoking increases the risk, but it is known that smoking makes your immune system weaker which could cause a persistent HPV infection (White et al, 2020).

Individuals can further lower their risk of developing HPV by having fewer sexual partners, using condoms or other types of barrier contraception when they have any type of sex: while this does not mitigate the risk completely it does reduce it (Macmillan, 2021). Health promotion is a key element in reducing the risk factors associated with HPV and health professionals should include this as part of their consultation.

Self-testing for HPV: next steps

With the introduction of HPV primary screening there is an opportunity for individuals to self-sample in the privacy and convenience of their own home. Both Australia and the Netherlands have incorporated this into their cervical screening programmes and have seen an increase in women being screened (Fedyanova, 2018). Self-testing for HPV screening is currently being piloted in the UK and has been since January 2021 in North and East London (NHS England, 2021). If the home test detects HPV, the individuals will be invited to attend their GP practice for a standard smear test. This initiative aims to increase the number of individuals completing cervical screening by making screening easier and more accessible for individuals who may not attend routine screening in primary care.

Conclusion

Cervical cancer is preventable and curable, and with the continued HPV vaccination programme and the recent change from cervical cytology to primary HPV screening, the UK is well placed to meet the World Health Organization's global strategy to accelerate the elimination of cervical cancer (WHO, 2020a). The early detection of HPV-positive samples allows for timely and effective monitoring and treatment and health professionals have a key role to play in this.

KEY POINTS:

• The National Cervical Screening Programme and the introduction of the human papillomavirus (HPV) vaccination in 2008 in the UK has been a significant step in preventing cervical cancer
• From December 2019, the cervical screening process changed from a cytology based test to HPV primary screening in primary care
• HPV has been detected in more than 99.7% of cervical cancers
• The World Health Organization has recently launched a Global Strategy to Accelerate the Elimination of Cervical Cancer and identifies three key steps: vaccination; screening; and treatment
• Self-testing for HPV screening is currently being piloted in the UK and has been since January 2021 in North and East London

CPD reflective practice:

• Consider your cervical screening consultations. What information do you currently give to individuals about human papillomavirus (HPV) and the significance of cervical screening results? Having read the article, are there any gaps in the information you give and, if so, how will you address these?
• What questions about lifestyle and health promotion would you want to ask an individual to advise them about reducing risks of HPV infection?