BACKGROUND Familial breast cancer risk studies usually overlook the dynamic nature of family history. METHODS The authors assessed the effect of incorporating the timing of cancer diagnosis events into the assessment of familial risks of breast cancer in first-degree and second-degree relatives in a nationwide cohort study of 5,099,172 women (follow-up was between 1958-2015). Family history was assessed using 3 approaches: 1) as a static variable (ever having a relative with breast cancer); 2) as accumulative history; and 3) as a dynamic variable (time-dependent variable). RESULTS For women aged <50 years, familial risk was mostly higher when family history was assessed as a dynamic variable compared with using a static or accumulative family history. For example, the cumulative risk of receiving a breast cancer diagnosis until age 50 years for women with a history of breast cancer in 1 first-degree relative was 2.6% (95% CI, 2.5%-2.7%) using the static method, 2.4% (95% CI, 2.3%-2.4%) using the accumulative method, and 3.1% (95% CI, 3.0%-3.2%) using the dynamic method. Relative risk in women aged <50 years with a breast cancer diagnosis in a sister was 1.40-fold (95% CI, 1.31-fold to 1.48-fold) using the static method, 1.66-fold (95% CI, 1.57-fold to 1.76-fold) using the accumulative method, and 2.28-fold (95% CI, 2.07-fold to 2.51-fold) using the dynamic method. CONCLUSIONS The results of the current study demonstrated that assessing family history as static, accumulative, or dynamic results in different familial risk estimates. The answer as to which method to use for family history assessment depends on the implications of the study, with the dynamic method appearing to be better suited for risk stratification studies, the accumulative method being the most convenient in practice and the least favored for risk prediction, and the static method being suitable for etiological impact and risk attribution studies.

中文翻译：

---

通过动态、累积和静态家族史定义来确定乳腺癌的家族风险。


背景家族性乳腺癌风险研究通常忽视家族史的动态性质。方法 作者在一项涉及 5,099,172 名女性的全国队列研究中评估了将癌症诊断事件的时间纳入一级和二级亲属乳腺癌家族风险评估中的效果（随访时间为 1958 年至 2015 年） 。使用 3 种方法评估家族史：1）作为静态变量（曾经有亲属患有乳腺癌）； 2）作为累积历史； 3) 作为动态变量（随时间变化的变量）。结果 对于 <50 岁的女性，与使用静态或累积家族史相比，当家族史作为动态变量进行评估时，家族风险大多更高。例如，使用静态方法，对于 1 名一级亲属有乳腺癌病史的女性，在 50 岁之前接受乳腺癌诊断的累积风险为 2.6%（95% CI，2.5%-2.7%），2.4使用累积方法为 %（95% CI，2.3%-2.4%），使用动态方法为 3.1%（95% CI，3.0%-3.2%）。使用静态方法，年龄为 <50 岁且姐妹诊断为乳腺癌的女性的相对风险为 1.40 倍（95% CI，1.31 倍至 1.48 倍），使用静态方法时为 1.66 倍（95% CI，1.57 倍至 1.57 倍）。使用累积法为1.76倍），使用动态法为2.28倍（95% CI，2.07倍至2.51倍）。结论 当前研究的结果表明，以静态、累积或动态方式评估家族史会导致不同的家族风险估计。 使用哪种方法进行家族史评估取决于研究的意义，动态方法似乎更适合风险分层研究，累积方法在实践中最方便，但最不适合风险预测，静态方法适用于病因影响和风险归因研究。