Sahlgrenska Cancer Center, University of Gothenburg, Box 425, 405 30, Göteborg, Sweden,
Cancer Immunol Immunother. 2013 Oct;62(10):1547-51. doi: 10.1007/s00262-013-1458-y. Epub 2013 Aug 24.
Late divergence of survival curves of treated patients and controls is commonly seen in successful cancer immunotherapy trials. Although late survival curve divergence may be caused by a delayed action of therapy, it may also be related to early effects of the treatment. We suggest that late survival divergence most often reflects a specific benefit of therapy for patients who suffer from a comparatively slow progression of disease. The occurrence of delayed survival curve divergence has important implications for the statistical analysis of immunotherapy trials. Thus, it leads to non-proportional hazard ratios that make commonly used statistical tests, e.g., the logrank test, suboptimal. It is therefore suggested that the statistical analysis of immunotherapy trials primarily should be based on a test that compares the survival curves at or after a prespecified, fixed, late time point.
在成功的癌症免疫疗法试验中，通常会观察到治疗患者和对照组的生存曲线后期分离。虽然晚期生存曲线分离可能是由于治疗的延迟作用引起的，但也可能与治疗的早期效果有关。我们认为，晚期生存曲线分离最常反映了对疾病进展相对较慢的患者的治疗的特定益处。延迟生存曲线分离的发生对免疫疗法试验的统计分析具有重要意义。因此，它导致非比例风险比，从而使常用的统计检验（例如对数秩检验）变得不理想。因此，建议免疫疗法试验的统计分析主要应基于在预先指定的固定晚期时间点或之后比较生存曲线的检验。
