A case-control study of the possible association between oral contraceptives and malignant melanoma

Abstract

Summary.-In a case-control study, we investigated 169 women aged 15-49 years with malignant melanoma notified to the Oxford and South Western cancer registries during the years 1971-76, together with 507 matched controls. Data about medical, reproductive, drug and smoking histories were obtained both by reviewing general practitioner (GP) records and from the women themselves by postal questionnaires. There was no significant evidence of any overall increase in the risk of melanoma in oral contraceptive (OC) users (data from GP records-ever use vs never use, relative risk (RR) 1.34, 9500 confidence limits 0.92-1 96; corresponding data from postal questionnaires-RR 1-13, limits 0.73-1-75). However, although not significant, the risk estimated from data in the postal questionnaires was higher in women who had used OCs for 5 years or more (use ;5 yrs vs never use, RR 1.57, limits 0-83-3.03).Previously demonstrated risk factors for melanoma, such as fair skin, blonde or red hair and Celtic origin were found to be commoner in the cases than in the controls.Data from the Oxford/Family Planning Association contraceptive study were also examined. Unexpectedly there was a strong suggestion of a negative association between OC use and melanoma risk, but the analysis was based on only 12 women with the disease.

Oral contraceptive use and malignant melanoma in Australia

“…In California the relative risk associated with other oestrogen use was 1.8 (Beral et al, 1977); in Washington State it was approximately 1.0 (Holly et al, 1983); in Percentages in parentheses. England, 1.4 (Adam et al, 1981), and in our study the figure was 1.6. While none is statistically significant, all except for the Washington data show a consistent increase in risk.…”

“…Most reported a weak association or none at all for melanoma and ever having used oral contraceptives. In contrast, however, all four which examined data on prolonged oral contraceptive use reported an increased risk associated with long term pill use (Beral et al, 1977;Adam et al, 1981;Bain et al, 1982;Holly et al, 1983), although the increase was not always statistically significant. We report here the findings of a case control study carried out in New South Wales, Australia, designed to examine these relationships.…”

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(Beral et al, 1977;Adam et al, 1981;Bain et al, 1982;Holly et al, 1983), although the increase was not always statistically significant. We report here the findings of a case control study carried out in New South Wales, Australia, designed to examine these relationships.

Methods

The study design has been described elsewhere (Beral et al, 1982

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“…A number of recent studies have reported on the relationship between past oral contraceptive use and malignant melanoma (Beral et al, 1977;Ramcharan et al, 1981;Adam et al, 1981;Kay, 1981;Bain et al, 1982;Holly et al, 1983). Most reported a weak association or none at all for melanoma and ever having used oral contraceptives.…”

A pooled analysis of 10 case–control studies of melanoma and oral contraceptive use

“…Relative risk estimates ranged from 1.4 to 3.5. However, these findings were based on a relatively small number of cases, and another cohort study found no excess risk (Adam et al, 1981). Subsequent case -control and cohort studies (Bain et al, 1982;Holly et al, 1983Holly et al, , 1995Holman et al, 1984;Helmrich et al, 1984;Beral et al, 1984;Gallagher et al, 1985;Green and Bain, 1985;Østerlind et al, 1988;Zanetti et al, 1990;Hannaford et al, 1991;Le et al, 1992;Palmer et al, 1992;Westerdahl et al, 1996;Gefeller et al, 1998;Smith et al, 1998;Feskanich et al, 1999) provided little evidence of an overall excess risk among ever users compared to never users, but a possible increase among long-term users (summarised in (Prentice and Thomas, 1987)).…”