Cervical Dysplasia and Cancer and the Use of Hormonal Contraceptives
Background: This study was conducted to determine whether use of hormonal contraceptives is associated with cervical dysplasia and cancer in a population where there is widespread use of hormonal contraception and the rates of cervical cancer remain high at 27.5/100,000.
Methods: A case-control study was conducted among women visiting the colposcopy and gynaelogical clinics at a tertiary referral hospital. Two hundred and thirty six cases CIN I (72), II (59), III (54), cancer (51) and 102 controls, consented and were interviewed on use of contraceptives using a structured questionnaire. Logistic regression was used to determine odds ratios (ORs) and 95% confidence intervals (CIs) associated with use of hormonal contraception in cases and controls and in low and high risk cases. Recruitment was carried out from 2001-2002.
Results: Contraceptives used were: oral contraceptives - 35%, injections (depot medroxy progesterone acetate (Depo-provera) - 10%, Intrauterine devices - 2%, combinations of these and tubal ligation - 30%. 23% reported use of 'other' methods, barrier contraceptives or no form of contraception. Barrier contraceptive use was not significantly different between cases and controls. Current and/or past exposure to hormonal contraceptives (HC) by use of the pill or injection, alone or in combination with other methods was significantly higher in the cases. In multivariate analysis with age and number of sexual partners as co-variates, use of hormonal contraception was associated both with disease, [OR, 1.92 (CI 1.11, 3.34; p = 0.02] and severity of the disease [OR, 2.22 (CI 1.05, 4.66) p = 0.036]. When parity and alcohol consumption were added to the model, hormonal contraception was no longer significant. The significant association with high risk disease was retained when the model was controlled for age and number of sexual partners. Depo-provera use (with age and number of sexual partners as covariates) was also associated with disease [OR, 2.43 (CI 1.39, 4.57), p = 0.006] and severity of disease [OR 2.51 (1.11, 5.64) p = 0.027]. With parity and alcohol added to this model, depo-provera use retained significance. Exposure to HC > 4 years conferred more risk for disease and severity of disease.
Conclusion: Hormonal contraception did confer some risk of dysplasia and women using HC should therefore be encouraged to do regular Pap smear screening.
The search for links between the use of hormonal contraception or hormone replacement therapy and the development of some reproductive system cancers in women has yielded conflicting results. Thus there is evidence of a correlation between estrogen and increased risk of breast cancer while on the other hand, it has been suggested that use of oral contraceptives for one year or more is protective against endometrial and ovarian cancers with the protective effect lasting for at least 10 years. There are several studies which have reported that hormonal contraception (HC) - pills and injectables - moderately increase the risk of cervical cancer as well as being a risk for all stages of cervical cancer particularly in human papilloma virus (HPV)-positive women thus suggesting that oral contraceptives may act as a promoter for HPV-induced carcinogenesis.
The inconsistent reports of an association between hormonal contraception and cervical dysplasia and cancer may be related, in part, to confounding risk factors that include sexual and lifestyle behaviours. The causal link between HPV and cervical dysplasia and cancer is now generally accepted. In addition to any direct effect of HC on the development of cervical dysplasia, either as an initiator or promoter of carcinogenesis, the use of hormonal contraceptives could result in women indulging in more unprotected sexual activity putting them at more risk of HPV and other STI infections and their sequelae.
Since the 1960s, use of HC for family planning has been actively encouraged in Jamaica. In addition to pills, Depot medroxy progesterone acetate (DMPA) injections and lovonorgestrel implants are available. Data from a Reproductive Health Survey by the National Family Planning Board (2002) showed that in addition to a doubling in the use of condoms, since 1989, there has been a 48% increase in the use of injectables (22.7% vs 33.6%) in women reporting ever use of contraception. Over the period, pill use rose from 47.6% to 56.5%.
Given the high incidence of cervical dysplasia and that cervical cancer rates remain high at 27.5/100,000, we looked at whether HC use in the population was a factor in the development of cervical dysplasia and cancer.