3月7日，Lancet Oncology杂志发表的一篇报告指出，即使在停止雌激素治疗最长达5年后，浸润性乳腺癌的发生率仍然显著降低。
这是对妇女健康行动(WHI)中的7,645名参与者进行的一项延长随访研究，由西雅图市Fred Hutchinson肿瘤研究中心的Garnet L. Anderson博士及其同事进行。WHI是一项多中心、随机试验，共纳入10,000例以上的妇女，将接受马结合雌激素治疗的受试者的预后与接受匹配安慰剂治疗的受试者进行比较。WHI的干预阶段在平均随访7年后，于2004年2月提前终止。接近78%的研究受试者（3,778名之前被随机分配到接受雌激素治疗组，3,867名被分配到安慰剂组）同意继续参与持续至2009年8月的延长随访研究，总的中位随访时间为11.8年。
结果显示，在最终的评估中，于干预阶段接受雌激素治疗中位时间为6年的妇女浸润性乳腺癌的总发病率为每年0.27%（151例），而安慰剂组妇女年发病率为0.35%，差异具有统计学意义。 “雌激素对乳腺癌发生的这种持续性、干预后预防作用，与其他经证实可降低乳腺癌发病率的激素靶向药物相似” (Lancet Oncol. 2012 March 7 [doi:10.1016/S1470-2045(12)70075-x])，并且，在发生乳腺癌的受试者中，雌激素组的全因死亡率（30例患者死亡，年死亡率为0.046%）显著低于安慰剂组（50例患者死亡，年死亡率为0.076%）。接受雌激素治疗者的乳腺癌特异性死亡率（6例患者死亡，年死亡率为0.009%）也显著低于安慰剂组（16例患者死亡，年死亡率为0.024%）。从结果来看，预防作用似乎局限于乳腺癌风险较低的妇女，对于有良性乳腺疾病病史或有一级乳腺癌家族史的妇女并不适用。亚组分析发现，雌激素的保护作用与患者年龄、体重指数、卵巢切除状态、绝经期开始后年数、既往雌激素使用情况或是否出现血管舒缩症状之间无相互作用。
研究者总结认为，绝经后妇女接受雌激素治疗，对乳腺癌具有长期预防作用。
WHI是由美国国立心肺血液研究所、美国卫生与公共服务部以及惠氏公司资助的。Anderson 博士的一位合作者披露与阿斯利康、诺华、安进和辉瑞公司之间存在利益关系。Anderson博士及其他研究者披露无相关利益冲突。（生物谷Bioon.com）
doi:10.1016/S1470-2045(12)70075-X
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Conjugated equine oestrogen and breast cancer incidence and mortality in postmenopausal women with hysterectomy: extended follow-up of the Women's Health Initiative randomised placebo-controlled trial
Prof Garnet L Anderson PhD a , Prof Rowan T Chlebowski MD b, Aaron K Aragaki MS a, Prof Lewis H Kuller MD c, Prof JoAnn E Manson MD d, Prof Margery Gass MD e, Elizabeth Bluhm MD f, Prof Stephanie Connelly MD g, Prof F Allan Hubbell MD h, Prof Dorothy Lane MD i, Lisa Martin MD j, Prof Judith Ockene PhD k, Prof Thomas Rohan MBBS l, Prof Robert Schenken MD m, Prof Jean Wactawski-Wende PhD
Background
By contrast with many observational studies, women in the Women's Health Initiative (WHI) trial who were randomly allocated to receive oestrogen alone had a lower incidence of invasive breast cancer than did those who received placebo. We aimed to assess the influence of oestrogen use on longer term breast cancer incidence and mortality in extended follow-up of this cohort.
Methods
Between 1993 and 1998, the WHI enrolled 10 739 postmenopausal women from 40 US clinical centres into a randomised, double-masked, placebo-controlled trial. Women aged 50—79 years who had undergone hysterectomy and had expected 3-year survival and mammography clearance were randomly allocated by a computerised, permuted block algorithm, stratified by age group and centre, to receive oral conjugated equine oestrogen (0·625 mg per day; n=5310) or matched placebo (n=5429). The trial intervention was terminated early on Feb 29, 2004, because of an adverse effect on stroke. Follow-up continued until planned termination (March 31, 2005). Consent was sought for extended surveillance from the 9786 living participants in active follow-up, of whom 7645 agreed. Using data from this extended follow-up (to Aug 14, 2009), we assessed long-term effects of oestrogen use on invasive breast cancer incidence, tumour characteristics, and mortality. We used Cox regression models to estimate hazard ratios (HRs) in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00000611.
