The impact of hormonal contraceptive therapy on a community and effects on cytopathology of the cervix

Oral Contraceptives and Cervical Neoplasia: Pooled Information from Retrospective and Prospective Epidemiologic Studies

A positive association between the use of oral contraceptives and the risk of cervical neoplasia has been suggested by different sources. This paper examines epidemiologic evidence on this issue through pooled computation of relative risks emerging from 21 studies, subdivided into three main categories: studies based on routine cytologic screening programs, case-control investigations and prospective studies. The pooled estimates of the relative risks for ever vs never use of oral contraceptives were broadly similar and slightly above unity (1.4 from cytologic screening programs, 1.1 from case-control and 1.4 from prospective studies). The risk increased with duration of use and, generally, lower relative risk estimates derived from the older studies, necessarily based on short-term use of oral contraceptives. A particularly limited increase in risk was apparent from case-control investigations. Furthermore, when allowance was made for the major covariates (mostly indicators of sexual habits), a noticeable decrease in the excess risk was evident. In conclusion, although statistical significance of moderate differences in risk can be obtained by pooling data from several studies, a risk of the magnitude of that for the association between oral contraceptives and cervical neoplasia may well be due to bias and confounding. In addition, since sexual behavior only indicates the probability of having been exposed to some sexually transmitted agent (most likely human papilloma virus), the greatest additional contribution may come from a case-control study in which adjustment for such exposure is possible.

Evaluation of the carcinogenic effects of estrogens, progestins and oral contraceptives on cervix, uterus and ovary of animals and man

Estrogens do not have the general biological effect of increasing the occurrence of cancer in various species of laboratory animals. The neoplastic effect of estrogens in animals is strain and species dependent. Estrogens may increase the incidence of uterine cervical cancer in some strains of mice, but not in other strains or other animal species. The progestins and oral contraceptives (OC) have not induced cervical cancer in animals and most studies demonstrate that the steroid anovulants do not increase the occurrence of abnormal cervical smears or cervical cancer in women. Estrogens increase the occurrence of endometrial cancer in the rabbit, occasionally in the mouse, but apparently not in other species. Case-control studies in menopausal and postmenopausal women indicate an increased risk of endometrial carcinoma (EC) associated with use of estrogen. However, in other studies estrogen has not been related to EC. Cases of EC have been reported in women using sequential OC but a causal relationship has not been established. Progestins alone may arrest progress or cause regression of EC in women. EC has not been related to use of the combination OC, and it is unlikely that use of these anovulants will lead to the development of endometrial cancer. Estrogens or OC do not induce a carcinogenic response in the ovary. A decrease in ovarian cysts, is observed during the clinical use of OC.

Dysplasias of uterine cervix: epidemiological aspects: role of age at first coitus and use of oral contraceptives

Age at first coitus and use of oral contraceptives were studied in a highly homogeneous population (French Canadian) during a cytologic cervical cancer screening program. Both factors were known in 84,540 women without cervical lesions and in 2017 patients with mild and moderate dysplasia. Highly significant correlations were found between: early onset of sexual activity and occurrence of dysplasia; oral contraceptive use and occurrence of dysplasia; early age at first coitus and oral contraceptive use. When correlated for age at first coitus, there was a significant excess of dysplasias in oral contraceptive users. Dysplasia of the uterine cervix behaves epidemiologically like carcinoma in situ and invasive squamous carcinoma, that is, essentially as a venereal disease. It remains to be seen whether all dysplasias form one continuum or whether there are two morphologically similar but biologically distinct forms of dysplasia: one more frequent, regressing spontaneously, the other relatively rare, progressing to carcinoma in situ and invasive squamous carcinoma of the cervix.

Oral contraceptives and cervical carcinoma

In a case-control study, 689 consecutive patients with cervical carcinoma were studied for their use of oral contraceptives. The control patients were matched for age, ethnic origin, age at first pregnancy, age at first coitus, and socioeconomic status. There was no significant difference between case and control subjects in the duration or oral contraceptive use, the type of estrogen used, or the years in which oral contraceptives were used. The mean duration of oral contraceptive use was 30.9 months by the case subjects and 30.2 months by the control subjects.

Carcinoma of the cervix in oral contraceptive steroid and IUD users and nonusers

A total of 40,211 cytologic examinations and subsequent diagnostic procedures resulted in the diagnosis of carcinoma of the cervix in 76 patients. The 76 patients did not demonstrate any variations in use of oral contraceptive steroids or intrauterine devices when compared to 780 randomly selected control patients. This study is in agreement with our earlier report demonstrating no increased risk of carcinoma of the cervix in oral contraceptive steroid users compared to nonusers.