Anderson William F, Chen Bingshu E, Brinton Louise A, Devesa Susan S
Biostatistics Branch, DHHS/NIH/NCI/DCEG, EPS, Bethesda, MD 20892-7244, USA.
Cancer Causes Control. 2007 Dec;18(10):1187-98. doi: 10.1007/s10552-007-9057-x. Epub 2007 Sep 6.
Prior to 1999-2000, breast cancer incidence rates had risen for decades, though more among older than younger women.
To further explore the impact of advancing age-at-diagnosis upon breast cancer incidence, we used the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program (1974-2003).
Over time, we observed age interactions by tumor grade, stage, and race. For example, among women ages <40 years, high-grade lesions were more common than low-grade tumors for all time periods. Among women ages 40+ years, high-grade lesions were more common during early time periods then trend lines crossed, after which low-grade tumors were more common than high-grade lesions. Notably, the transition (crossover point) occurred earlier with advancing age-at-diagnosis.
The reversal (crossing) of incidence rates from high to low-grade tumors among women 40+ years is a qualitative age interaction, probably due to changing age-related risk factor and/or screening patterns, where mammography preferentially detected tumors of low malignant potential among older women. Though once thought to be rare or artifactual, qualitative age interactions suggest breast cancer heterogeneity. Indeed, if real, qualitative age interactions (effect modifications) imply different etiologic pathways for early-onset and late-onset types of breast cancer.
在1999 - 2000年之前的几十年里，乳腺癌发病率一直在上升，不过老年女性的上升幅度大于年轻女性。
为了进一步探究确诊年龄增长对乳腺癌发病率的影响，我们使用了美国国立癌症研究所的监测、流行病学和最终结果（SEER）计划（1974 - 2003年）。
随着时间的推移，我们观察到肿瘤分级、分期和种族方面的年龄交互作用。例如，在年龄小于40岁的女性中，所有时间段内高级别病变都比低级别肿瘤更常见。在年龄40岁及以上的女性中，早期高级别病变更常见，然后趋势线交叉，此后低级别肿瘤比高级别病变更常见。值得注意的是，随着确诊年龄的增加，这种转变（交叉点）出现得更早。
40岁及以上女性中肿瘤发病率从高级别向低级别转变（交叉）是一种定性的年龄交互作用，可能是由于与年龄相关的危险因素和/或筛查模式的变化，其中乳腺钼靶检查优先检测出老年女性中低恶性潜能的肿瘤。尽管定性年龄交互作用曾被认为罕见或具有人为性，但它提示了乳腺癌的异质性。事实上，如果是真实的，定性年龄交互作用（效应修饰）意味着早发型和晚发型乳腺癌的病因途径不同。
