Abstract
Objective: To compare two methods for calculating lifetime ovulatory cycles (LOC) to determine if more detailed menstrual cycle information results in stronger associations with ovarian cancer. Methods: Using data from 232 cases and 242 controls in a population-based study of ovarian cancer, we compared a standard method for calculating LOC with a second method that had more detailed information on menstrual characteristics. Odds ratios for ovarian cancer by number of LOC were estimated using unconditional logistic regression. Results: The average number of LOC was 29 fewer for the second method that had more detailed menstrual cycle information, as compared to the standard method (p < 0.0001). The difference was due primarily to the second method considering episodes of missed/irregular periods. Associations between LOC and ovarian cancer were weaker for the second method than the standard method. Further analyses suggested that a reduced number of ovulatory cycles due to menstrual irregularity was associated with increased ovarian cancer risk, in contrast to the protective effects observed for fewer ovulatory cycles due to pregnancy or oral contraceptive use. Conclusion: Obtaining additional details on menstrual factors that affect LOC, particularly missed or irregular cycles, provides important information on ovarian cancer risk. Our data suggest that episodes of anovulation due to menstrual disturbances should be evaluated separately from anovulation due to pregnancy or oral contraceptive use.
Similar content being viewed by others
References
Fathalla MF (1971) Incessant ovulation-a factor in ovarian neoplasia? Lancet 2: 163.
Cramer DW, Welch WR (1983) Determinants of ovarian cancer risk. II. Inferences regarding pathogenesis. J Natl Cancer Inst 71: 717–721.
Risch HA (1998) Hormonal etiology of epithelial ovarian cancer, with a hypothesis concerning the role of androgens and progesterone. J Natl Cancer Inst 90: 1774–1786.
Whittemore AS, Harris R, Itnyre J, and the Collaborative Ovarian Cancer Group (1992) Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. IV. The pathogenesis of epithelial ovarian cancer. Am J Epidemiol 136: 1212–1220.
Schildkraut JM, Bastos E, Berchuck A (1997) Relationship between lifetime ovulatory cycles and overexpression of mutant p53 in epithelial ovarian cancer. J Natl Cancer Inst 89: 932–938.
Webb PM, Green A, Cummings MC, Purdie DM, Walsh MD, Chenevix-Trench G (1998) Relationship between number of ovulatory cycles and accumulation of mutant p53 in epithelial ovarian cancer. J Natl Cancer Inst 90: 1729–1734.
Weiss NS, Cook LS, Farrow DC, Rosenblatt KA. Ovarian cancer. In: Schottenfeld D, Fraumeni JF Jr., eds. Cancer Epidemiology and Prevention. New York: Oxford University Press, pp. 1040–1057.
Whittemore AS, Harris R, Itnyre J, and the Collaborative Ovarian Cancer Group (1992) Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. II. Invasive epithelial ovarian cancers in white women. Am J Epidemiol 136: 1184–1203.
Siskind V, Green A, Bain C, Purdie D (2000) Beyond ovulation: oral contraceptives and epithelial ovarian cancer. Epidemiology 11: 106–110.
De Leo V, Lanzetta D, Morgante G, De Palma P, D'Antona. (1997) Inhibition of ovulation with transdermal estradiol and oral progestogens in perimenopausal women. Contraception 55: 239–243.
Schildkraut JM, Schwingl PJ, Bastos E, Evanoff A, Hughes C (1996) Epithelial ovarian cancer risk among women with polycystic ovary syndrome. Obstet Gynecol 88: 554–559.
Ries LAG, Kosary CL, Hankey BF, Miller BA, Clegg LX, Edwards BK (eds) (1999) SEER Cancer Statistics Review, 1973–1996. NIH Publ. No. 99–2789. Bethesda, MD: National Cancer Institute.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Moorman, P.G., Schildkraut, J.M., Calingaert, B. et al. Ovulation and ovarian cancer: a comparison of two methods for calculating lifetime ovulatory cycles (United States). Cancer Causes Control 13, 807–811 (2002). https://doi.org/10.1023/A:1020678100977
Issue Date:
DOI: https://doi.org/10.1023/A:1020678100977