Sector of Medical Oncology, Institute of Oncology Ljubljana, Ljubljana, Slovenia.
Department of Oncology, McMaster University, Hamilton, Ontario.
Ann Oncol. 2012 Nov;23(11):2977-2982. doi: 10.1093/annonc/mds174. Epub 2012 Jun 24.
Reporting of relative risk reduction as the measure of treatment effect in randomized clinical trials (RCTs) may be difficult to understand. Here, we compare two methods for assessing absolute benefits of anticancer therapies.
We searched PubMed for RCTs comparing therapies for breast and colorectal cancers published 1975-2009 (adjuvant setting) and 2000-2010 (metastatic setting). Eligible trials reported statistically significant differences. Kaplan-Meier curves were assessed for absolute differences in time-to-event end points at a single point (snapshot method) and as the area between curves (area method). Pooled absolute benefits determined by both methods were compared by the Pitman-Morgan test.
Eighty-three and 39 paired curves were assessed in the adjuvant and metastatic settings, respectively. In trials of adjuvant therapy, absolute benefits were larger and more variable when assessed at different time points by the snapshot compared with the area method (median and ranges for 60-month difference in overall survival: 7.6% [2.5%-28.4%] and 4.5% [1.8%-13.6%]; P = 0.002, respectively). For metastatic disease, both methods were within 0.5 month of each other in 62% of trials.
The area method provides an alternative measure of absolute treatment effect, which uses all of the available data and is less dependent on the shape of survival curves.
在随机临床试验（RCT）中，以风险降低比作为治疗效果的衡量指标可能难以理解。在此，我们比较了两种评估抗癌疗法绝对获益的方法。
我们在 PubMed 中检索了 1975 年至 2009 年（辅助治疗）和 2000 年至 2010 年（转移性疾病）发表的比较乳腺癌和结直肠癌治疗方法的 RCT 研究。纳入的试验报告了有统计学意义的差异。通过 Kaplan-Meier 曲线评估在单个时间点（快照法）和曲线之间区域（面积法）的时间依赖性终点的绝对差异。通过 Pitman-Morgan 检验比较两种方法确定的累积绝对获益。
分别评估了辅助治疗和转移性疾病环境下的 83 个和 39 个配对曲线。在辅助治疗试验中，与面积法相比，快照法在不同时间点评估的绝对获益更大且更具变异性（60 个月总生存率差异的中位数和范围：7.6%[2.5%-28.4%]和 4.5%[1.8%-13.6%]；P = 0.002）。对于转移性疾病，两种方法在 62%的试验中相差不到 0.5 个月。
面积法提供了一种替代的绝对治疗效果衡量方法，它利用了所有可用的数据，并且对生存曲线的形状依赖性更小。
