Summary of Evidence
Avoidance of Human Papillomavirus Infection
Screening via Gynecologic Examinations and Cytologic Screening
Cigarette Smoke
Reproductive Behavior
Note: Separate PDQ summaries on Cervical Cancer Screening and Cervical
Cancer Treatment are also available.
Avoidance of Human Papillomavirus Infection
Based on solid evidence, the following measures are effective to avoid human papillomavirus (HPV) infection, and thus cervical cancer:
Abstinence from sexual activity
Description of the Evidence
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Study Design: Evidence obtained from cohort and case-control studies.
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Internal Validity: Good.
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Consistency: Good.
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Magnitude of Effects on Health Outcomes: Abstinence prevents HPV infection.
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External Validity: Good.
Barrier protection and/or spermicidal gel during sexual intercourse
Description of the Evidence
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Study Design: Evidence obtained from cohort and case-control studies.
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Internal Validity: Good.
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Consistency: Good.
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Magnitude of Effects on Health Outcomes: Total use of barrier protection decreases cancer incidence, relative risk of 0.4 (95% confidence interval [CI], 0.2–0.9).
Based on fair evidence, vaccination against HPV-16/HPV-18 is effective to avoid HPV infection, and thus cervical cancer.
Description of the Evidence
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Study Design: Evidence obtained from randomized controlled trials.
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Internal Validity: Good.
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Consistency: Not applicable.
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Magnitude of Effects on Health Outcomes: Vaccination against HPV-16 and HPV-18 reduces incident and persistent infections with efficacy of 91.6% (95% CI, 64.5–98.0) and 100% (95% CI, 45–100), respectively. Duration of efficacy is not yet known.
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External Validity: Good.
Screening via Gynecologic Examinations and Cytologic Screening
Based on solid evidence, screening via regular gynecologic examinations and cytologic test (Papanicolaou smear) with treatment of precancerous abnormalities decreases the incidence and mortality of cervical cancer.
Description of the Evidence
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Study Design: Evidence obtained from cohort or case-control studies.
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Internal Validity: Good.
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Consistency: Good.
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Magnitude of Effects on Health Outcomes: Estimates from population studies suggest that screening may decrease cancer incidence and mortality by more than 80%.
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External Validity: Good.
Cigarette Smoke
Based on solid evidence, cigarette smoking, both active and passive, increases the risk of cervical cancer.
Description of the Evidence
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Study Design: Evidence obtained from cohort or case-control studies.
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Internal Validity: Good.
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Consistency: Good.
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Magnitude of Effects on Health Outcomes: Among HPV-infected women, current and former smokers have approximately two to three times the incidence of high-grade cervical intraepithelial neoplasia or invasive cancer. Passive smoking is also associated with increased risk, but to a lesser extent.
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External Validity: Good.
Reproductive Behavior
High parity
Based on solid evidence, high parity is associated with increased risk of cervical cancer.
Description of the Evidence
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Study Design: Evidence obtained from cohort or case-control studies.
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Internal Validity: Good.
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Consistency: Good.
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Magnitude of Effects on Health Outcomes: Among HPV-infected women, women who have had seven or more full-term pregnancies have approximately four times the risk of squamous cell cancer compared with nulliparous women and two to three times the risk of women who have had one or two full-term pregnancies.[1]
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External Validity: Good.
Long-term use of oral contraceptives
Based on solid evidence, long-term use of oral contraceptives is associated with increased risk of cervical cancer.
Description of the Evidence
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Study Design: Evidence obtained from cohort or case-control studies.
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Internal Validity: Good.
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Consistency: Good.
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Magnitude of Effects on Health Outcomes: Among HPV-infected women, women who used oral contraceptives for 5 to 9 years have approximately three times the incidence of invasive cancer, and those who used them for 10 years or longer have approximately four times the risk.[2]
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External Validity: Good.
References
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Muñoz N, Franceschi S, Bosetti C, et al.: Role of parity and human papillomavirus in cervical cancer: the IARC multicentric case-control study. Lancet 359 (9312): 1093-101, 2002.
[PUBMED Abstract]
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Moreno V, Bosch FX, Muñoz N, et al.: Effect of oral contraceptives on risk of cervical cancer in women with human papillomavirus infection: the IARC multicentric case-control study. Lancet 359 (9312): 1085-92, 2002.
[PUBMED Abstract]
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