Article date: April 2008
Human papillomavirus and cervical cancer
Human papillomavirus (HPV) is a sexually transmitted infection that can cause cervical cancer. Most women are infected with HPV at some point, but most infections, even those caused by high-risk viral subtypes, disappear naturally without causing any problem.
Contraceptives and cervical cancer: reanalysis of data1
Combined oral contraceptives (COCs) have long been thought to be associated with a small increased risk of cervical cancer. Whether this association is due directly to the effect of COCs or whether it reflects, at least partly, confounding effects of other factors such as smoking, number of sexual partners, and age at first intercourse has been unclear. New data adds to the evidence that COCs have a role in the development of cervical cancer.
The latest report has reanalysed data for more than 16,500 women with cervical cancer and found that current use of COCs for 5 years or longer is accompanied by an increased risk of cervical cancer (relative risk 1·90 [95% CI 1·69–2·13]). The baseline risk of cervical cancer increases with age, and the number of extra cases in COC users increases with age.
The new report estimates that:
- women who use COCs for 5 years from age 20 years have increased cumulative incidence of cervical cancer at age 50 years from 38 cases per 10,000 (in never-users) to 40 cases per 10,000 (ie, an extra 2 cases per 10,000)
- women who use COCs for 10 years from age 20 years have increased cumulative incidence of cervical cancer at age 50 years from 38 cases per 10,000 (in never-users) to 45 cases per 10,000 (ie, an extra 7 cases per 10,000)
Risk falls when COCs are stopped; after about 10 years, risk reaches the same level as that for never-users of COCs.
The data suggest that the risk of cervical cancer in users of progestogen-only injectable contraceptives (ie, Depo-Provera and Noristerat) may be similar to that for COC users.
No epidemiological data is available for the risk of cervical cancer in users of Evra ▼ (a combined hormonal contraceptive patch), NuvaRing, (a combined hormonal intravaginal contraceptive), progestogen-only pills, Implanon (a progestogen-only implant), or Mirena (a progestogen-only intrauterine device).
Regular cervical screening checks the health of the cervix and can reduce the risk of cervical cancer. Failure to attend cervical screening is one of the biggest risk factors for development of cervical cancer. In England cervical screening is offered at 3–5-year intervals to all women age 25–64 years. In Scotland, cervical screening is offered between age 20 years and 60 years, and in Northern Ireland and Wales the service is offered to women age 20–64 years. Women should be encouraged to attend cervical screening.
Routine vaccination against HPV infection will be introduced in autumn 2008 for girls age 12–13 years. A 2-year catch-up programme will start from September 2009 for girls aged up to 18 years. However, girls who have been vaccinated against HPV should attend regular cervical smears when they reach the appropriate age because the vaccine does not protect against all HPV subtypes that may cause cervical cancer.
Article citation: Drug Safety Update April 2008; Vol 1, Issue 9: 2
International Collaboration of Epidemiological Studies of Cervical Cancer. Lancet 2007; 370: 1609–21 ↩