Cervical cancer risk of Hormonal Contraception

In some studies HCs have been associated with an increased risk of cervical abnormalities and cervical cancer, but there might be alternative explanations for these epidemiological associations: HC users can start having sexual intercourse at an earlier age, they have more sexual partners, and they rarely use barrier methods of contraception ^(46,47).

Nevertheless, combined oral contraceptives are classified by the International Agency for Research on Cancer as a cause of cervical cancer.

As the incidence of cervical cancer increases with age, the public-health implications of this association depend largely on the persistence of effects long after use of oral contraceptive has ceased. Among current users of oral contraceptives the risk of invasive cervical cancer increased with increasing duration of use (relative risk= RR for 5 or more years' use versus never use, 1.90) ⁽⁴⁸⁾.

The risk declined after use ceased, and by 10 or more years had returned to that of never users.A similar pattern of risk was seen both for invasive and in-situ cancer, and in women who tested positive for high-risk human papillomavirus (HPV).

Relative risk did not vary substantially between women with different characteristics. Ten years' use of oral contraceptives from around age 20 to 30 years is estimated to increase the cumulative incidence of invasive cervical cancer by age 50 from 7.3 to 8.3 per 1000 in less developed countries and, from 3.8 to 4.5 per 1000 in more developed countries ^(49,50,51).

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Recent studies suggest that long duration use of oral contraceptives increases the risk of cervical cancer in HPV positive women. Cervical cancer is caused by specific types of the human papilloma virus (HPV)but, not all infected women develop cancer. It was hypothesized that HC can act as a promoter for HPV-induced carcinogenesis ^(52,53).

Available data showed an increase in the transcription of high-risk HPV by the 16alpha–hydroxylation of estrogens and this finding explains the increased cervical carcinogenesis risk for long-term contraceptive using,HPV-infected women ^(53,54).

Results from published studies were combined to examine the relationship between invasive and in situ cervical cancer and duration of use of hormonal contraceptives, with particular attention to HPV infection ^(55,56).

Twenty-eight eligible studies were identified, together including 12.531 women with cervical cancer. Compared with never users of oral contraceptives, the relative risks of cervical cancer increased with increasing duration of use: for durations of approximately less than 5 years, 5-9 years, and 10 or more years, respectively, the summary relative risks were 1.1, 1.6, and 2.2 for all women,respectively.