联用口服避孕药与终生癌症风险

http://www.medscape.com/medline/abstract/28188769

 Lifetime cancer risk and combined oral contraceptives: the Royal College of General Practitioners' Oral Contraception Study. Am J Obstet Gynecol. 2017; 216(6):580.e1-580.e9 (ISSN: 1097-6868) Iversen L; Sivasubramaniam S; Lee AJ; Fielding S; Hannaford PC

BACKGROUND: Oral contraceptives have been used by hundreds of millions of women around the world. Important questions remain regarding the very long-term cancer risks that are associated with oral contraception. Despite previous research, important questions remain about the safety of these contraceptives: (1) How long do endometrial, ovarian, and colorectal cancer benefits persist? (2) Does combined oral contraceptive use during the reproductive years produce new cancer risks later in life? (3) What is the overall balance of cancer among past users as they enter the later stages of their lives? 

背景： 全球使用口服避孕药的妇女始终数以亿计，与口服避孕药相关的非常长期的癌症风险一直是重大问题。尽管以往曾有研究，但口服避孕药的安全性仍是重要问题：(1)子宫内膜癌、卵巢癌、结直肠癌的获益持续多久？(2) 在生育年龄口服避孕药联用是否在年龄较大时产生新的癌症风险？(3)既往使用口服避孕药者在步入其较晚年龄段时其总体癌症平衡如何？

OBJECTIVES: The purpose of this study was to examine the very long-term cancer risks or benefits associated with the use of combined oral contraceptives, including the estimated overall life-time balance. 

目的

本研究的目的是检查与口服避孕药相关的非常长期的癌症风险或获益，包括估计终生平衡。

STUDY DESIGN: The 46,022 women who were recruited to the UK Royal College of General Practitioners' Oral Contraception Study in 1968 and 1969 were observed for up to 44 years. Directly standardized rates of specific and any cancer were calculated for "ever" and "never" users of combined oral contraceptives; data were standardized for age, parity, social class, and smoking. Attributable risk and preventive fraction percentages were calculated. Poisson regression that adjusted for the same variables was used to estimate incidence rate ratios between ever and never users and to examine effects by time since last oral contraceptive use. 

研究设计

1968年、1969年募集至项目“the UK Royal College of General Practitioners' Oral Contraception Study”的46,022例女性，观察至44年。计算“用过”（ever）和“从未用过”（never）联用口服避孕药妇女特定或任意癌症直接标准化发病率。数据按年龄、分娩次数、社会阶层、吸烟与否标准化，计算特异危险性与预防分数百分数，使用Poisson回归估计“用过”与“从未用过”联用口服避孕药妇女两群体发病率比，检查最后一次使用口服避孕药的时间效应。

RESULTS: There were 4661 ever users with at least 1 cancer during 884,895 woman-years of observation and 2341 never users with at least 1 cancer during 388,505 woman-years of observation. Ever use of oral contraceptives was associated with reduced colorectal (incidence rate ratio, 0.81; 99% confidence interval, 0.66-0.99), endometrial (incidence rate ratio, 0.66; 99% confidence interval, 0.48-0.89), ovarian (incidence rate ratio, 0.67; 99% confidence interval, 0.50-0.89), and lymphatic and hematopoietic cancer (incidence rate ratio, 0.74; 99% confidence interval, 0.58-0.94). An increased risk of lung cancer was seen only among ever users who smoked at recruitment. An increased risk of breast and cervical cancer that was seen in current and recent users appeared to be lost within approximately 5 years of stopping oral contraception, with no evidence of either cancer recurring at increased risk in ever users with time. There was no evidence of new cancer risks appearing later in life among women who had used oral contraceptives. Thus, the overall balance of cancer risk among past users of oral contraceptives was neutral with the increased risks counterbalanced by the endometrial, ovarian, and colorectal cancer benefits that persist at least 30 years. 

结果

在观察的884,895人年期间，4661 例“用过”联用口服避孕药的妇女至少罹患1种癌症；在观察的388,505人年期间，2341例“从未用过”联用口服避孕药的妇女至少罹患有1种癌症。“用过”联用口服避孕药与以下癌症发病率减低相关：结直肠癌（发病率比0.81; 99%置信限0.66-0.99），子宫内膜癌 (发病率比0.66; 99%置信限0.48-0.89),卵巢癌(发病率比 0.67; 99% 置信限0.50-0.89), and 淋巴和造血系统癌症 (发病率比0.74; 99% 置信限0.58-0.94). 肺癌风险增高仅见于被募集时是吸烟者的“用过”联用口服避孕药妇女。见于当前或最近使用口服避孕药妇女的乳癌和宫颈癌风险增高，似乎在停用口服避孕药约5年内消失，在使用口服避孕药妇女无癌症复发风险增高的证据。在使用口服避孕药妇女并无在随后的较大年龄段出现新肿瘤的证据。如此，在过去使用过口服避孕药的妇女其癌症风险总平衡是中性的：至少持续30年在子宫内膜癌、卵巢癌和结直肠癌方面的获益起了平衡作用。

CONCLUSION: Most women who choose to use oral contraceptives do not expose themselves to long-term cancer harms; instead, with some cancers, many women benefit from important reductions of risk that persist for many years after stopping. 

结论：

大多数选择使用口服避孕药的妇女没有暴露于长期癌症伤害，相反，许多妇女某些肿瘤的风险减低，且停用口服避孕药后仍可持续多年。

standardized rates of specific and any cancer, "特定或任意癌症直接标准化率", 这里把and译作"或",也许是笔误. 我觉得是"和/而且".因为下文的results,告诉我们既有at least 1 cancer 的数据又有colorectal 等癌症数据.