, Volume 14, Issue 2, pp 151-160

Breast cancers among very young premenopausal women (United States)

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Abstract

Objective: To assess risk factors for breast cancer among very young compared to older premenopausal women. Methods: Between 1990 and 1992 a population-based case–control study conducted in Atlanta, GA, Seattle/Puget Sound, WA, and central NJ interviewed 3307 premenopausal women aged 20–54 years. Logistic regression models estimated adjusted relative risks (RR) and 95% confidence intervals (CI) for each of three 10-year age groups. Results: Among the youngest age group (<35 years, n = 545), significant predictors of risk included African-American race (RR = 2.66; 95% CI 1.4–4.9) and recent use of oral contraceptives (RR = 2.26; 95% CI 1.4–3.6). Although these relationships were strongest for estrogen receptor-negative (ER−) tumors (RRs of 3.30 for race and 3.56 for recent oral contraceptive use), these associations were also apparent for young women with ER+ tumors. Delayed childbearing was a risk factor for ER+ tumors among the older premenopausal women (p trend < 0.01), but not for women <35 years in whom early childbearing was associated with an increased risk, reflecting a short-term increase in risk immediately following a birth. Family history of early-onset breast cancer was more strongly associated with risk among women <35 years (RR = 3.22) than those 45–54 years (RR = 1.51). Risk factors for premenopausal breast cancer not significantly modified by age at diagnosis included early age at menarche, low body mass index, and heavy alcohol consumption. Conclusion: These findings suggest the possibility that women who develop breast cancers at very young ages may be etiologically as well as clinically distinct.