Invasive Breast Cancer Incidence in 2,305,427 Screened Asymptomatic Women: Estimated Long Term Outcomes during Menopause Using a Systematic Review

BackgroundEarlier studies of breast cancer, screening mammography, and mortality reduction may have inflated lifetime and long-term risk estimates for invasive breast cancer due to limitations in their data collection methods and interpretation.ObjectiveTo estimate the percentage of asymptomatic peri/postmenopausal women who will be diagnosed with a first invasive breast cancer over their next 25 years of life.MethodsA systematic review identified peer-reviewed published studies that: 1) enrolled no study participants with a history of invasive breast cancer; 2) specified the number of women enrolled; 3) reported the number of women diagnosed with a first invasive breast cancer; 4) did not overcount [count a woman multiple times]; and, 5) defined the length of follow-up. Data sources included PubMed, Cochrane Library, and an annotated library of 4,409 full-text menopause-related papers collected and reviewed by the first author from 1974 through 2008. Linear regression predicted incidence of first invasive breast cancer, based on follow-up duration in all studies that met the our inclusion criteria, and in a subset of these studies that included only women who were 1) at least 50 years old and 2) either at least 50 or less than 50 but surgically menopausal at enrollment.ResultsNineteen studies met the inclusion criteria. They included a total of 2,305,427 peri/postmenopasual women. The mean cumulative incidence rate of first invasive breast cancer increased by 0.20% for each year of age (95% CI: 0.17, 0.23; p 2 = 0.90). Over 25 years of follow-up, an estimated 94.55% of women will remain breast cancer-free (95% CI: 93.97, 95.13). In the 12 studies (n = 1,711,178) that enrolled only postmenopausal women, an estimated 0.23% of women will be diagnosed with a first invasive breast cancer each year (95% CI: 0.18, 0.28; p 2 = 0.88).ConclusionThe vast majority (99.75%) of screened asymptomatic peri/postmenopasual women will not be diagnosed with invasive breast cancer each year. Approximately 95% will not be diagnosed with invasive breast cancer during 25 years of follow-up. Women who receive clinical examinations, but do not have mammograms, will have higher cancer-free rates because innocuous positives (comprising 30-50% of mammography diagnoses) will remain undetected. Informed consent to asymptomatic women should include these results and consideration of the benefits of avoiding mammograms.背景 既往针对乳腺癌、筛查性乳腺钼靶摄影（screening mammography）与死亡率降低的相关研究，由于数据收集方法与解读方式存在局限，可能高估了侵袭性乳腺癌（invasive breast cancer）的终身及长期风险估算值。 研究目的 估算无症状围绝经期/绝经后女性在未来25年寿命中被诊断为首发侵袭性乳腺癌的比例。 方法 本研究通过系统综述筛选符合以下条件的同行评议已发表研究：1）未纳入有侵袭性乳腺癌病史的研究对象；2）明确报告入组女性人数；3）报告被诊断为首发侵袭性乳腺癌的女性人数；4）未重复计数（即同一名女性不会被多次计入）；5）明确界定随访时长。数据来源包括PubMed、Cochrane图书馆，以及第一作者在1974年至2008年间收集并审阅的4409篇绝经相关全文文献的注释化数据库。基于符合本研究纳入标准的全部研究的随访时长，以及仅纳入以下两类女性的亚组研究：1）至少50岁；2）≥50岁，或<50岁但入组时已手术绝经，通过线性回归预测首发侵袭性乳腺癌的发病率。 结果 共有19项研究符合纳入标准，共纳入2305427名围绝经期/绝经后女性。首发侵袭性乳腺癌的平均累积发病率随年龄每增长1年升高0.20%（95%置信区间：0.17，0.23；p²=0.90）。在25年随访期间，预计94.55%的女性仍未罹患乳腺癌（95%置信区间：93.97，95.13）。在仅纳入绝经后女性的12项研究（共1711178名女性）中，预计每年有0.23%的女性被诊断为首发侵袭性乳腺癌（95%置信区间：0.18，0.28；p²=0.88）。 结论 每年接受筛查的无症状围绝经期/绝经后女性中，绝大多数（99.75%）不会被诊断为侵袭性乳腺癌。在25年随访期间，约95%的女性不会被诊断为侵袭性乳腺癌。仅接受临床检查而未行乳腺钼靶摄影的女性，其无癌生存率更高，原因是占乳腺钼靶摄影诊断病例30%~50%的无害假阳性结果不会被检出。向无症状女性提供知情同意时，应纳入上述研究结果，并告知其规避乳腺钼靶摄影的获益。