International Agency for Research on Cancer (IARC) classifies the role of this risk factor in cancer development.
All cervical cancers in the UK are linked to HPV, because HPV is a necessary cause of cervical cancer;[2,3] however some HPV types are high-risk for cervical cancer, others are low-risk.
HPV infection is common, but progresses to cervical cancer in a minority of cases. Around 12% of women without cervical abnormalities in the UK and Ireland are infected with high-risk HPV types, a meta-analysis has shown. The highest prevalence is in younger women. Around half of HPV infections clear within 6-12 months, though high-risk HPV types persist longer than low-risk types, a meta-analysis showed.
Fewer than 10% of persistent HPV infections progress to carcinoma in situ, which left untreated, can progress to cervical cancer.
HPV16 and HPV18 account for 58% and 16% respectively of all cervical cancer cases in Europe, a pooled analysis showed. These types are protected against by the UK HPV vaccination programme.
Cervical cancer risk is not associated with infection with low-risk HPV types, cohort studies have shown.[8,9] Cervical cancer risk is higher in women with genital warts (GW) versus those without, a cohort study showed; though GW are usually caused by low-risk HPV types (6 and 11), co-infection with high-risk HPV types is likely.
Other factors may be associated with cervical cancer risk because they increase the risk of Human papillomavirus (HPV) exposure or persistent HPV infection (and/or may have direct effects, independent of HPV).
Cervical cancer risk is almost three times higher in women who have had 6 or more sexual partners, compared with those who have had only one, a pooled analysis showed. Cervical cancer risk is around doubled in women who first had sexual intercourse aged 14 or younger, compared with those who did so aged 25 or older, a pooled analysis showed.
Cervical cancer risk is around halved in women whose only current male sexual partner is circumcised, compared with those whose partner is uncircumcised, a pooled analysis showed; HPV prevalence is lower in circumcised versus uncircumcised men, a meta-analysis showed.