Gestational trophoblastic disease refers to a spectrum of rare benign andmalignant gynecologic disorders whose pathogenesis is not well understood. Recent studies fromChina and the United States have raised the hypothesis that long-term use of oral contraceptivesbefore conception may increase the risk of gestational trophoblastic tumors. A multicentercase-control study of gestational trophoblastic tumors was undertaken to test this hypothesis.Methods
Telephone interviews were conducted with 235 case patients, including 50 withgestational choriocarcinoma, and 413 control subjects matched on recentness of pregnancy, ageat pregnancy, and area of residence. Relative risks (odds ratios) were computed by conditionallogistic regression. Reported P values are two-sided.Results
The relative riskestimate for ever having used oral contraceptives before the index pregnancy was 1.9(95% confidence interval [CI]=1.2–3.0), and the risk increased withduration of use (P for trend=.05). The estimate was highest for women whoused oral contraceptives during the cycle in which they became pregnant (relative risk=4.0; 95% CI=1.6–10), but there was no consistent pattern according to the timeinterval since last use. Separate analyses of choriocarcinoma and persistent mole yielded similarresults, i.e., the relative risk estimates for oral contraceptive use were 2.2 (95% CI=0.8–6.4) and 1.8 (95% CI=1.0–3.0), respectively. Control for the numberof sexual partners, which was independently associated with risk (P for trend=.05), did not materially change the results.Conclusions
This study, the largest to date,indicates that long duration of oral contraceptive use before conception increases the risk ofgestational trophoblastic tumors. These findings may provide clues to the pathogenesis of thisrare disease. Changes in use of oral contraceptives are not warranted, however, because theincidence attributable to oral contraceptive use is very low.