致密乳腺发生对侧乳腺癌风险增加近两倍

　　乳腺癌患者10年内出现对侧乳腺癌风险约2%～40%，变化范围较大，主要取决于患者人群多个风险因素的可变性。根据既往多个研究，原发性和继发性乳腺癌的风险因素包括乳腺癌易感基因（BRCA）突变、家族史、肿瘤雌激素受体状态等。乳腺密度也是原发性乳腺癌的最重要危险因素之一，是否为乳腺癌患者对侧乳腺疾病的风险因素尚不可知。

　　2017年1月30日，美国癌症学会官方期刊《癌症》在线发表德克萨斯大学MD安德森癌症中心和公共卫生学院的研究报告，发现致密型乳腺癌发生对侧乳腺癌的风险增加近两倍。

　　该病例对照回顾研究入组1997年1月～2012年12月MD安德森癌症中心Ⅰ～Ⅲ期乳腺癌患者680例，其中病例组为初次诊断乳腺癌超过6个月出现对侧乳腺癌者229例，对照组为根据发病年龄、诊断年份、激素受体状态等因素按1∶2进行匹配的无对侧乳腺癌者451例。根据首次诊断乳腺癌时的钼靶乳腺密度，将患者分为非致密和致密，分析原发性乳腺癌患侧乳腺密度与发生对侧乳腺癌之间的相关性。

　　结果发现，病例组的非致密和致密患者分别占39.3%、60.7%，而对照组的非致密和致密患者分别占48.3%、51.7%。

　　经过对乳腺癌的可能预后风险因素进行调整后，乳腺致密与非致密的患者相比，发生对侧乳腺癌的风险高1.8倍（比值比：1.80，95%置信区间：1.22～2.64，P＜0.01）。接受化疗或内分泌疗法的患者发生对侧乳腺癌的风险较低。

　　该研究可能是第一个发现乳腺密度与对侧乳腺癌之间相关性的研究，对于患侧乳腺致密的乳腺癌患者有重要意义，可以根据该研究结果对乳腺癌存活者的长期二次复发风险进行管理。未来的研究目标是建立乳腺密度风险模型，对乳腺癌存活者的对侧乳腺癌风险进行更好评估，并希望能够使用该模型，帮助对侧乳腺癌风险较高患者对其治疗选择、早期筛查等给出较好建议。

Cancer. 2017 Jan 30. [Epub ahead of print]

Mammographic breast density is associated with the development of contralateral breast cancer.

Raghavendra A, Sinha AK, Le-Petross HT, Garg N, Hsu L, Patangan M Jr, Bevers TB, Shen Y, Banu A, Tripathy D, Bedrosian I, Barcenas CH.

The University of Texas MD Anderson Cancer Center, Houston, Texas; The University of Texas School of Public Health, Houston, Texas.

BACKGROUND: Women with dense mammographic breast density (BD) have a 2-fold increased risk of developing primary breast cancer (BC). The authors hypothesized that dense mammographic BD also is associated with an increased risk of developing contralateral breast cancer (CBC).

METHODS: Among female patients treated at The University of Texas MD Anderson Cancer Center for sporadic, AJCC stage I to stage III BC between January 1997 and December 2012, the authors identified patients who had developed metachronous CBC (cases) and selected 1:2 matched controls who did not develop CBC using incidence density sampling, matched on attainted age, year of diagnosis, and hormone receptor status of the first BC. Mammographic BD, assessed at the time of first BC diagnosis, was categorized as "nondense" (American College of Radiology breast categories of fatty or scattered density) or "dense" (American College of Radiology categories of heterogeneously dense or extremely dense). Multivariable conditional logistic regression models were used for statistical analysis.

RESULTS: A total of 229 cases and 451 controls were evaluated. Among the cases, approximately 39.3% had nondense breast tissue and 60.7% had dense breast tissue. Among controls, approximately 48.3% had nondense breast tissue and 51.7% had dense breast tissue. After adjustment for potential prognostic risk factors for BC, the odds of developing CBC were found to be significantly higher for patients with dense breasts (odds ratio, 1.80; 95% confidence interval, 1.22-2.64 [P<.01]) than for those with nondense breasts. Patients who received chemotherapy or endocrine therapy were less likely to develop CBC.

CONCLUSIONS: In women with primary BC, mammographic BD appears to be a risk factor for the development of CBC.

KEYWORDS: contralateral breast cancer; dense; mammographic breast density; nondense

PMID: 28135395

DOI: 10.1002/cncr.30573

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