Lê M G, Charreau I
INSERM U287, institut Gustave-Roussy, Villejuif, France.
Bull Cancer. 1991;78(4):357-63.
The study of the association between oral contraceptives (OC) and benign breast disease (BBD) is of great interest for the epidemiologist, because of the impact that this association may have on the risk of breast cancer. In fact, three factors have to be analysed simultaneously: OC use, the occurrence of BBD and the occurrence of breast cancer. This analysis is complex because two out of the three factors are not univocal in their definition (various composition and doses for pills, numerous histologic types of BBD). Moreover, a fourth parameter is to take into account: the time factor. This last factor intervenes in the chronological order of events (OC before or after BBD), and for the use of different types of pills (duration of use, age at the start of OC use before or after the first full-term pregnancy, etc). Although all the relationships between these different factors are still insufficiently known at the present time, certain points are acquired: 1) OC use decreases the risk of BBD (particularly when pills contain high doses of progestogens); 2) a history of BBD increases the risk of breast cancer (particularly when BBD is a fibrocystic mastosis with cellular atypia); 3) in spite of the decrease in the risk of BBD associated with OC use, OC use does not decrease the risk of breast cancer. For a long time, this third proposition appeared as paradoxal. In 1986, Stadel and Schlesselman tried to estimate the terms of this paradoxe. Their estimations allowed to show that the risk of breast cancer associated with OC use, for women with a history of BBD, was overestimated in all previous reports. Indeed, the decrease of the occurrence of BBD due to OC use, which was associated with an important reduction in the number of breast cancer cases, was not taken into account in the estimation of this risk. Other epidemiological investigations with a greater number of subjects are needed to further analyse complex relationships between OC use, BBD and breast cancer.
口服避孕药（OC）与乳腺良性疾病（BBD）之间关联的研究，对流行病学家来说极具吸引力，因为这种关联可能会对乳腺癌风险产生影响。事实上，必须同时分析三个因素：OC的使用、BBD的发生以及乳腺癌的发生。这种分析很复杂，因为这三个因素中有两个在定义上并不明确（避孕药的成分和剂量各不相同，BBD有多种组织学类型）。此外，还有一个参数需要考虑：时间因素。最后这个因素会影响事件的时间顺序（OC是在BBD之前还是之后使用），以及不同类型避孕药的使用情况（使用时长、首次足月妊娠之前或之后开始使用OC的年龄等）。尽管目前这些不同因素之间的所有关系仍未被充分了解，但已经有一些确定的观点：1）使用OC可降低BBD的风险（特别是当避孕药含有高剂量孕激素时）；2）BBD病史会增加患乳腺癌的风险（特别是当BBD是伴有细胞异型性的纤维囊性乳腺病时）；3）尽管使用OC会降低与BBD相关的风险，但使用OC并不会降低患乳腺癌的风险。长期以来，这第三个观点似乎自相矛盾。1986年，斯塔德尔和施莱塞尔曼试图评估这个矛盾的情况。他们的评估表明，在之前所有的报告中，有BBD病史的女性使用OC相关的乳腺癌风险被高估了。事实上，在评估这种风险时，没有考虑到使用OC导致BBD发生率降低这一情况，而这与乳腺癌病例数的大幅减少相关。还需要更多受试者参与的其他流行病学调查，以进一步分析OC使用、BBD和乳腺癌之间的复杂关系。
