A CASE CONTROL STUDY INTO THE POSSIBLE EFFECTS OF BIRTH CONTROL PILLS ON PRE-CLINICAL CARCINOMA OF THE CERVIX

In British Columbia (1969-1970) the possible effects of oral contraceptives and other socio-economic factors on the development of pre-clinical squamous carcinoma of the cervix were studied in 310 patients with pre-clinical cervical carcinoma and in 682 controls all of whom were either 20-24 or 25-29 years of age. The overall use of contraceptives was similar among positive cases and controls. The mean interval between first use of contraceptives and entry into the study was 5.3 years for the 25-29 year-old patients with preclinical carcinoma of the cervix while the interval for the 20-24-year-old patients was 2.9 years. Oral contraceptives were the most acceptable contraceptive especially among the younger women. No significant difference in the pattern or duration of oral contraceptive usage was found between the case and control groups. The pattern of contraceptive usage in the 1970 screened population of the entire province of British Columbia paralleled that in the study group except for a lower rate of sequential-preparation use. No positive relationship was found between use of oral contraception and pre-clinical carcinoma. The possibility that long-run exposure to orals may be carcinogenic cannot be ruled out without further follow-up. In terms of the social data there was a significantly greater pregnancy rate higher parity and greater frequency of divorce multiple marriages and common law relationships among positive cases than among controls suggesting different patterns of social behavior in the 2 groups.