Oral Contraceptives and Breast Cancer Risk Among Younger Women

Abstract

The relationship between oral contraceptives and breast cancer in young women appears to have a biologic basis rather than to be an artifact or the result of bias.

The association between oral contraceptive use and lobular and ductal breast cancer in young women

“…Although the primary aim of the WISH study was to examine breast cancer risk in younger women in relation to patterns of oral contraceptive use, 22 it was not designed specifically to evaluate hypotheses about lobular breast cancer. Lobular cancers are a small proportion of all breast cancer cases diagnosed, and the mean age at diagnosis for lobular breast cancer is older than the mean age at diagnosis for ductal cancer, 36 and so it was expected that there would be a small number of lobular cases in the WISH population.…”

“…22 Cases were recruited from metropolitan Atlanta, GA, Seattle-Puget Sound, WA, and a 5-county area in central New Jersey and were defined as any woman between 20 and 44 years of age who was diagnosed with incident in situ or invasive breast cancer between May 1, 1990 and December 31, 1992. Eligible cases were identified using rapid reporting systems established in each of the 3 geographic areas and checks were made against population-based cancer registries in these same areas.…”

“…Oral contraceptive use variables were created based on categories used in previously published studies. 22,24,26,29,30 Lifetime oral contraceptive use of 6 months or longer was treated as 'ever useÕ. Oral contraceptive use of less than 6 months or no use at all was treated as 'never useÕ.…”

“…It has been consistently shown that oral contraceptive use is associated with an increased risk of breast cancer in young women, [12][13][14][15][16][17][18][19][20][21][22][23][24][25] but not older women. 21,[23][24][25] Recently, Newcomer et al 26 reported that current oral contraceptive use, recent use, and older age at first use are associated with an increased risk of invasive lobular breast cancer, but not invasive ductal breast cancer in a population of middleaged women, suggesting that oral contraceptives may have effects related to specific histologic subtypes.…”

Oral contraceptive use at a young age and the risk of breast cancer: an Icelandic, population-based cohort study of the effect of birth year

“…Several studies have suggested an increased risk associated with recent or current use of oral contraceptives (Romieu et al, 1989; WHO Collaborative Study of Neoplasia and Steroid Contraceptives, 1990;Rookus and van Leeuwen, 1994;Brinton et al, 1995). This was recently confirmed by the comprehensive meta-analysis of the Collaborative Group on Hormonal Factors in Breast Cancer (1996).…”