Overview

Worldwide, every two minutes a woman dies of cervical cancer. Globally, cancer of the cervix is the second most prevalent cancer in women, causing nearly 500,000 new cases per year, and the third leading cause of female cancer deaths after breast and lung cancer (Ferlay et al 2004). Each year an estimated 270,000 women die from the disease, 85% of whom are from the developing world, where it kills more women than any other form of cancer (Ferlay et al 2004).

(Reference: Ferlay et al 2004)

Cervical cancer and its subsequent treatment may cause multiple survivorship challenges and quality-of-life disruptions, both during and long after treatment (Basen-Engquist et al 2003; Wenzel et al 2005; Pearman 2003). The diagnosis and treatment of pre-cancerous cervical abnormalities can also lead to significant anxiety (Khanna and Phillips 2001; Lerman et al 1991). Even minor abnormalities cause considerable anxiety for many women (Bell et al 1995). These anxieties include concerns about relationships and fertility to partner fidelity. In addition, considerable healthcare costs are associated with both screening for the disease and treating cervical cancer (Wolstenholme and Whynes 1998; Jacob et al 2005; Sankaranarayanan et al 2001; Sankaranarayanan et al 2005).

Given that cervical cancer affects many women in the prime of their lives, often while they are working and still responsible for children or other family members, the combined social, economic and emotional burden of cervical cancer is enormous (Wolstenholme and Whynes 1998; Wenzel et al 2005; Greimel et al 2002).

HPV Infections and Cervical Cancer

There are over 100 types of HPV, of which 30-40 can infect mucosal tissue. The others cause a variety of non-genital conditions, such as plantar warts (Wilson 2001; Burd 2003; von Krogh 2001). Of the types that can infect mucosal tissue, there are low-risk HPV types that can cause benign, low-grade lesions on the cervical surface or genital warts (which rarely progress to cancer). More importantly, there are over 15 oncogenic types that have been directly linked to cervical cancer (Bosch et al 2002; Schiller and Davies 2004; Muñoz et al 2003). Of these oncogenic HPV types, HPV 16 and 18 are the most important and are found in over 70% of cervical cancers globally (see figure below) (Muñoz et al 2004).

(Reference: Muñoz et al 2004)

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Contracting

HPV is a very common and easily transmittable virus. The risk of contracting HPV starts with the first sexual encounter and lasts throughout a woman’s sexually active life. Infection does not require full penetrative intercourse, as skin-to-skin contact in the genital area is enough to spread the infection. Condoms do not fully protect from cervical cancer (Schiffman and Kjaer 2003; Burd 2003).

Virtually all cases of cervical cancer are associated with HPV infection (Bosch et al 2002). Every sexually active woman is at risk of coming into contact with HPV (Baseman and Koutsky 2005). It is estimated that up to 50-80% of people will acquire an HPV infection in their lifetime (Baseman and Koutsky 2005; Ho et al 1998; Brown et al 2005) and up to 75% of those infections will be an oncogenic-type HPV infection (Peto 2004; Cushieri 2004). Most HPV infections usually resolve within six months to a year (Moscicki et al 1998; Giuliano et al 2002; Ho et al 1998). However, persistent infection with oncogenic types of HPV can lead to cervical cancer (Bosch et al 2002; Walboomers et al 1999).

Prior infection with HPV does not usually provide women with immunity against subsequent infections; nor does it eliminate the risk of an HPV infection becoming persistent. Therefore women continue to be at risk from infection with HPV throughout their sexually-active life (Stanley 2005; Mayrand et al 2000; Baseman and Koutsky 2005).

Prevention

Given the significant burden associated with cervical cancer, prevention and treatment strategies are critical (Franceschi 2005; Franco et al 2001). Proper screening requires well-organised acquisition of cervical samples at regular intervals (Sankaranarayanan et al 2005). This identifies abnormal cells on the cervix, which can be removed, if treatment is necessary.

Cervical screening is currently the only strategy for early detection of cervical abnormalities and HPV infections. The figure below shows how the incidence of cervical cancer can be significantly reduced in a country with a well-established screening programme (UK) compared to a country without an established screening programme (Brazil).

Age-specific incidence of Cervical cancer in Brazil and the UK
(Reference: Bosch et al 2003)

However, cervical screening does not prevent HPV infection, and it requires extensive healthcare resources (Sankaranarayanan et al 2005; Wolstenholme and Whynes 1998; NHS Cervical Screening Programme 2005). Furthermore, diagnosis and treatment of cervical abnormalities are associated with significant psychosocial costs to the affected woman (Lerman et al 1991; Bell et al 1995; Basen-Engquist et al 2003).

In addition, many women in developing countries do not have access to regular cervical screening. And even in countries with a screening programme, there are women who do not regularly attend and who therefore have an elevated risk of developing cervical cancer. In such countries, approximately 50% of cervical cancer occurs in women who do not attend for screening or who are not screened regularly (Schiller and Davies 2004; Leyden et al 2005; Stuart et al 1997).

Vaccination against HPV types could be a new approach to protecting women from the risk of cervical cancer, and vaccines are currently in development (Harper et al 2004; Muñoz et al 2004).

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