Unit of Health Care Epidemiology, Oxford University, Old Road Campus, Headington, Oxford OX3 7LF UK.
Contraception. 2013 Dec;88(6):678-83. doi: 10.1016/j.contraception.2013.08.008. Epub 2013 Sep 2.
This analysis provides the final results on cancer incidence in relation to oral contraceptive (OC) use from the Oxford-Family Planning Association (Oxford-FPA) contraceptive study, which closed at the end of 2010. An additional 6 years of observation have been added since our last report and there has been an increase in the numbers of cancers of over 50% at seven of the sites considered.
The Oxford-FPA study includes 17032 women aged 25-39 years recruited from 1968 to 1974 at contraceptive clinics in England and Scotland. These women were using OCs, a diaphragm or an intrauterine device. Information about cancer incidence among them has been collected from recruitment until closure of the study.
OC use was not related to nonreproductive cancer. Breast cancer findings (1087 cases) were entirely negative; the rate ratio (RR) comparing ever users of OCs with never users was 1.0 [95% confidence interval (CI): 0.9-1.1]. Only two cases of cervical cancer have been added since our last report (total: 61 cases); the RR comparing ever use with never use is now 3.4 (95% CI: 1.6-8.9). The risk of this disease increases sharply with duration of OC use and declines steadily with interval since last OC use. OC use protects against both uterine body cancer (124 cases) and ovarian cancer (143 cases). The RRs comparing ever use with never use were 0.5 (95% CI: 0.3-0.7) and 0.5 (95% CI: 0.4-0.7), respectively. Protection against both these cancers increased with duration of OC use and waned with interval since last use, but an effect was still present 28 or more years after discontinuation.
In our study, OC use had no effect on nonreproductive cancers or on breast cancer. The risk of cervical cancer was increased and that of uterine body cancer and ovarian cancer was decreased by OC use. All these effects increased with duration of use and declined with interval since last use. The beneficial effects of OC use on cancer outweighed the adverse effects. These findings should reassure older women who used OCs in the past.
本分析提供了与口服避孕药（OC）使用相关的癌症发病率的最终结果，该研究来自牛津计划生育协会（Oxford-FPA）避孕研究，该研究已于 2010 年底结束。自上次报告以来，又增加了 6 年的观察期，其中 7 个部位的癌症发病率增加了 50%以上。
牛津-FPA 研究包括 1968 年至 1974 年在英格兰和苏格兰的避孕诊所招募的 17032 名 25-39 岁的女性。这些女性正在使用 OCs、子宫帽或宫内节育器。自招募以来，一直在收集她们的癌症发病率信息，直到研究结束。
OC 使用与非生殖系统癌症无关。乳腺癌发现（1087 例）完全为阴性；与从未使用过 OCs 的女性相比，曾经使用过 OCs 的女性的比率比（RR）为 1.0[95%置信区间（CI）：0.9-1.1]。自上次报告以来，仅增加了两例宫颈癌病例（总计：61 例）；与从未使用过相比，现在的 RR 为 3.4（95%CI：1.6-8.9）。这种疾病的风险随着 OC 使用时间的延长而急剧增加，并随着最后一次 OC 使用以来的时间间隔而稳定下降。OC 使用可预防子宫体癌（124 例）和卵巢癌（143 例）。与从未使用过相比，曾经使用过的 RR 分别为 0.5（95%CI：0.3-0.7）和 0.5（95%CI：0.4-0.7）。OC 使用对这两种癌症的保护作用随着使用时间的延长而增加，随着最后一次使用以来的时间间隔而减弱，但在停药 28 年或更长时间后仍存在影响。
在我们的研究中，OC 使用对非生殖系统癌症或乳腺癌没有影响。OC 使用增加了宫颈癌的风险，降低了子宫体癌和卵巢癌的风险。所有这些影响都随着使用时间的延长而增加，并随着最后一次使用以来的时间间隔而减少。OC 使用对癌症的有益影响超过了不利影响。这些发现应该让过去使用过 OCs 的老年女性感到安心。
