Dumeaux Vanessa, Alsaker Elin, Lund Eiliv
University of Tromsø, Institute of Community Medicine, Tromsø, Norway.
Int J Cancer. 2003 Jul 20;105(6):844-50. doi: 10.1002/ijc.11167.
The aim of our study was to examine the risk of breast cancer according to specific types of estrogens and progestagens in oral contraceptives (OCs) based on the prospective Norwegian Women and Cancer study (NOWAC). Between 1991-97 women aged 30-70 years were drawn at random from the central person register and mailed an invitation and a questionnaire. Women (102,443) were enrolled with follow-up information collected throughout 1999 by linkage with national registries of cancer, mortality and emigration based on the unique national identification number. Among the 96,362 women included in the present analysis 851 invasive breast cancer were diagnosed. The adjusted risk of breast cancer increased with 25% for ever use of OCs and the risk increased with increasing duration of use (test for trend: p = 0.007). No association between time since last use and breast cancer risk was found after stratification on duration of use. Positive trend was still found for total duration of use among women who used OCs more than 5 years ago. Second generation of OCs had an increased risk with increasing duration of use. Classifying progestagens according to chemical groups, the relative risk increased significantly with increasing cumulative dose of levonorgestrel progestagen. It was difficult to conclude for the other groups due to lack of power. In a multivariate analysis the cumulative dose for all progestagen groups were non-significant, although we observed a significant increased risk with increasing milligram-months of estrogen exposure (p = 0.002). In conclusion, the increased risk of breast cancer related with OC formulations could be due mostly to estrogen component.
我们研究的目的是根据挪威女性与癌症前瞻性研究（NOWAC），探讨口服避孕药（OCs）中特定类型雌激素和孕激素与乳腺癌风险的关系。1991年至1997年间，从中央人口登记处随机抽取30至70岁的女性，给她们邮寄邀请函和问卷。共有102,443名女性入组，并在1999年通过与基于唯一国家识别码的癌症、死亡率和移民国家登记处进行关联，收集随访信息。在本分析纳入的96,362名女性中，诊断出851例浸润性乳腺癌。曾经使用OCs的女性患乳腺癌的校正风险增加了25%，且风险随着使用时间的延长而增加（趋势检验：p = 0.007）。在按使用时间分层后，未发现末次使用时间与乳腺癌风险之间存在关联。在5年多前使用过OCs的女性中，仍发现使用总时长呈正相关趋势。第二代OCs的风险随着使用时间的延长而增加。根据化学类别对孕激素进行分类，左炔诺孕酮类孕激素的累积剂量增加，相对风险显著增加。由于样本量不足，难以对其他组得出结论。在多变量分析中，所有孕激素组的累积剂量均无统计学意义，尽管我们观察到随着雌激素暴露毫克-月数的增加，风险显著增加（p = 0.002）。总之，与OC配方相关的乳腺癌风险增加主要可能归因于雌激素成分。
