Shantakumar Sumitra, Terry Mary Beth, Teitelbaum Susan L, Britton Julie A, Millikan Robert C, Moorman Patricia G, Neugut Alfred I, Gammon Marilie D
Department of Epidemiology, CB#7435 McGavran-Greenberg Hall, University of North Carolina School of Public Health, Chapel Hill, NC 27599-7435, USA.
Breast Cancer Res Treat. 2007 May;102(3):365-74. doi: 10.1007/s10549-006-9343-4. Epub 2006 Oct 11.
Reproductive factors have been shown to affect pre- and postmenopausal breast cancer risk differently, but whether there are additional age-specific differences among menopausal women as they age has not been clarified. We analyzed data from a large population-based case-control study that included 1,508 breast cancer cases and 1,556 controls, aged 20-98 years, who completed an in-home interviewer-administered questionnaire. The following subgroups were created to examine if the associations between reproductive factors and breast cancer risk varied by age- and menopausal-status: premenopausal (n=968), postmenopausal <65 years (n=1,045), postmenopausal >or=65 years (n=958). Among postmenopausal women >or=65 years, ever having breastfed decreased risk (odds ratio (OR)=0.67, 95% confidence interval (CI)=0.48, 0.92), and a strong dose-response relationship was observed for longer durations of breastfeeding (P trend=0.02), with the most pronounced protective effect observed for >or=14 months of breastfeeding (OR=0.40, 95% CI=0.21,0.76). Late age at first birth (AFB) and older age at last birth (ALB) were associated with non-statistically significant increases in breast cancer risk in this older group, while late age at menarche and surgical menopause decreased risk. ORs for multiparity were close to the null. Among premenopausal women and postmenopausal women <65 years, multiparity significantly decreased risk, and older AFB nonsignificantly increased risk. Our findings suggest that the well-known protective effect of multiparity attenuates with older age. Moreover, breastfeeding, one of the few potentially modifiable risk factors for breast cancer, was an important factor in decreasing risk among older parous postmenopausal women.
生殖因素对绝经前和绝经后乳腺癌风险的影响有所不同，但绝经后女性随着年龄增长是否存在其他特定年龄差异尚不清楚。我们分析了一项基于人群的大型病例对照研究的数据，该研究纳入了1508例乳腺癌病例和1556例对照，年龄在20 - 98岁之间，他们完成了一份由访员在家中进行询问的问卷。我们创建了以下亚组，以检验生殖因素与乳腺癌风险之间的关联是否因年龄和绝经状态而异：绝经前（n = 968）、绝经后<65岁（n = 1045）、绝经后≥65岁（n = 958）。在≥65岁的绝经后女性中，曾经哺乳可降低风险（比值比（OR）= 0.67，95%置信区间（CI）= 0.48，0.92），并且观察到母乳喂养时间越长，存在强烈的剂量反应关系（P趋势 = 0.02），母乳喂养≥14个月时观察到最显著的保护作用（OR = 0.40，95% CI = 0.21，0.76）。在这个年龄较大的组中，初产年龄晚（AFB）和末次生育年龄大（ALB）与乳腺癌风险非统计学显著增加相关，而月经初潮晚和手术绝经可降低风险。多产的OR值接近无效值。在绝经前女性和<65岁的绝经后女性中，多产显著降低风险，而AFB较大则非显著增加风险。我们的研究结果表明，多产的众所周知的保护作用会随着年龄增长而减弱。此外，母乳喂养是乳腺癌少数几个潜在可改变的风险因素之一，是降低年龄较大的经产绝经后女性风险的一个重要因素。
