© 1999 by Oxford University Press
Journal of the National Cancer Institute, Vol. 91, No. 7, 635-640,
April 7, 1999
© 1999 Oxford University Press
REPORTS |
Oral Contraceptive Use and Risk of Gestational Trophoblastic Tumors
Affiliations of authors: J. R. Palmer, L. Rosenberg, S. Shapiro, R. S. Rao, Slone Epidemiology Unit, Boston University School of Medicine, MA; S. G. Driscoll, Department of Pathology, Harvard Medical School, emerita, Boston; R. S. Berkowitz, New England Trophoblastic Disease Center, Brigham and Women's Hospital, Harvard Medical School; J. R. Lurain, Department of Obstetrics and Gynecology, John I. Brewer Trophoblastic Disease Center, Northwestern University Medical School, Chicago, IL; J. Soper, Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC; L. B. Twiggs, Department of Obstetrics and Gynecology, University of Minnesota Medical School, Minneapolis; D. M. Gershenson, Department of Gynecologic Oncology, The University of Texas M. D. Anderson Cancer Center, Houston; E. I. Kohorn, Department of Gynecology, Yale University School of Medicine, New Haven, CT; M. Berman, Department of Obstetrics and Gynecology, University of California at Irvine Medical Center.
Correspondence to: Julie R. Palmer, Sc.D., Slone Epidemiology Unit, Boston University School of Medicine, 1371 Beacon St., Brookline, MA 02446 (e-mail: jpalmer{at}slone.bu.edu).
BACKGROUND: Gestational trophoblastic disease refers to a spectrum of rare benign and malignant gynecologic disorders whose pathogenesis is not well understood. Recent studies from China and the United States have raised the hypothesis that long-term use of oral contraceptives before conception may increase the risk of gestational trophoblastic tumors. A multicenter case-control study of gestational trophoblastic tumors was undertaken to test this hypothesis. METHODS: Telephone interviews were conducted with 235 case patients, including 50 with gestational choriocarcinoma, and 413 control subjects matched on recentness of pregnancy, age at pregnancy, and area of residence. Relative risks (odds ratios) were computed by conditional logistic regression. Reported P values are two-sided. RESULTS: The relative risk estimate 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 with duration of use (P for trend = .05). The estimate was highest for women who used 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 time interval since last use. Separate analyses of choriocarcinoma and persistent mole yielded similar results, 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 number of 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 of gestational trophoblastic tumors. These findings may provide clues to the pathogenesis of this rare disease. Changes in use of oral contraceptives are not warranted, however, because the incidence attributable to oral contraceptive use is very low.
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