The effects of barrier and spermicidal methods of contraception on cervical cancer risk were examined by studying 479 cases of histologically confirmed invasive cervical cancer cases and 788 random digit dialing controls. In addition to a detailed history of contraceptive practices, information was available on numerous potential confounders, including demographic characteristics, sexual behavior, reproductive factors, Pap smear screening history, and smoking. After adjustment for relevant confounders, diaphragm and condom use were found not to be significantly associated with risk of cervical cancer. Although there was a small reduction in risk (OR = 0.8) associated with long-term use (5+ years) of the diaphragm, the effect appeared to relate to concomitant spermicide use, since there was evidence of further decreases in risk for women using spermicides alone for extended periods (OR = 0.7 for 5+ years). Effects were only seen among subjects of higher income and education levels, suggesting that patterns of usage may be important. The potential ability of spermicides to reduce cervical cancer risk by neutralizing viral agents warrants further attention.
PIP: A case-control study of cervical cancer and confounding factors barrier and spermicidal contraceptives, smoking, socio-economic status, and screening found that barrier methods confer no protection against cervical cancer, but spermicides may offer some protection. 479 cases diagnosed with invasive cervical cancer at 5 centers (Birmingham, Chicago, Denver, Miami and Philadelphia) and 788 community controls selected by random dialing were interviewed at home. Questions covered contraception, sociodemographics, pregnancies, menstruation, hygiene, sexual behavior, medical history, smoking, diet, marriage, and family history of cancer. 7 contraceptive methods, spermicides, diaphragm, condom, pill, IUD, female and male sterilization were analyzed. In unconditional logistic regression, at first barrier methods appeared to lower cancer risk. After controlling for age, race, education, income, last Pap smear, number of sex partners, barrier methods were not significant (odds ratio 1.2), with no significance in trend. Neither did duration of oral contraception or smoking alter the results. A slight insignificant decrease in risk was seen over time with diaphragm use. The odds ratio for vaginal spermicides was 1.0 with no trend for duration of use. For the small number of women reporting use of vaginal spermicides solely (11 cases and 29 controls) for 5 or more years, however, the odds ratio was 0.7 indicating protection against cervical cancer. The test for trend was not significant. Long-term users of spermicides were also less likely to develop cancer when ever-pill users were excluded from analysis. Analyzing only high socioeconomic groups, spermicide use gave an odds ratio of 0.5 for long-term use, and a significant trend for duration of use. Some explanations of these results were the possible protection of the whole vagina with spermicides compared to diaphragm or condom, and the potential use of larger quantities, or more consistent use of spermicides, by high socioeconomic groups of women. It is known that human papilloma virus may infects the penile shaft and that it can spread from the vagina to the cervix.