Neoplasia and dysplasia of the cervix uteri and contraception: a possible protective effect of the diaphragm

Abstract

Summary.-Among the 17,032 women included in the Oxford-Family Planning Association contraceptive study, 65 developed biopsy proven cervical neoplasia (including dysplasia) prior to 1 September 1977. The incidence rate in diaphragm users (0.17 per 1000 woman-years of observation) was much lower than the rates in oral contraceptive users or intrauterine device users (0.95 and 0-87 respectively). This difference could not be explained in terms of confounding variables, nor was it attributable to a lower frequency of cervical smearing among diaphragm users within the clinics.Detailed information about age at first intercourse, numbers of sexual partners and the frequency of cervical smearing outside the clinics was obtained from 52 of the women with cervical neoplasia and 139 matched controls. Diaphragm users were less likely to have had coitus at an early age and had had materially fewer sexual partners-tian users of the other two methods of contraception. After adjusting for the effects of these variables, however, the risk of cervical neoplasia in diaphragm users was still only about one quarter that in the users of the other methods. Patterns of smearing varied little between users of the various contraceptive methods.Smoking emerged as a major "risk factor" for cervical neoplasia in this study. This probably implies that the smoking habit reflects some important aspect of sexual behaviour relevant to the production of the disease that we have been unable to measure.

Characteristics of women with dysplasia or carcinoma in situ of the cervix uteri

“…others (Meisels et al, 1977;Wright et al, leato tce fto 1 978) and contrast with those of Thomas ariables have (1973). Thomas (Meisels et al, 1977;Peritz et al, 1977).…”

“…One problem in interpretation is the appropriateness of the group to which pill users are compared. Initially we thought that our findings might have been due to inclusion of diaphragm users in the control group, since use of the diaphragm may protect against cervical abnormalities, including cancer (Boyd & Doll, 1964;Boyce et al, 1977;Wright, et al, 1978). However, users of oral contraceptives still had higher risks than women who had not used barrier methods of contraception.…”

“…Thomas (1973) and Wright et al (1978) also found smoking to remain as a risk factor for carcinoma in situ and other cervical neoplasms after adjustment for several established risk factors. Although a causal relationship seems biologically implausible, and we did not find that risk among smokers increased with the number of cigarettes smoked (Table X) the association possibly deserves further investigation.…”

“…Several have found that patients with abnormal cervical smears were similar to women with invasive cancer in 26 respect of marital status and husbands' occupation (Samson et al, 1971;Wakefield et al, 1973). Wright et al (1978) reported that age at first marriage, age at first pregnancy, age at first coitus and number of sexual partners affected the risk of cervical neoplasia, but they did not have sufficient data to examine separately the risk factors for dysplasia, carcinoma in situ and invasive cancer. Meisels et al (1977) found that women with cervical dysplasia resembled those with carcinoma in situ and invasive carcinoma in respect of age at first coitus.…”

Cigarette smoking and cancer of the uterine cervix

“…An incidental finding in the analysis was an elevated risk of cervical neoplasia among cigarette smokers. At the time, a causal relationship between smoking and cervical cancer seemed unlikely, and our opinion was that smoking probably reflected some unmeasured characteristic of sexual behaviour which was important in producing the disease (Wright et al, 1978). Subsequent reports, however, have lent credence to a possible causal effect of smoking itself (Winkelstein et al, 1984) and we have re-examined the question using the more extensive data now available from the original group of women.…”