Cancer Immunology, Immunotherapy

, Volume 62, Issue 10, pp 1547–1551

Late divergence of survival curves in cancer immunotherapy trials: interpretation and implications

  • Fredrik B. Thorén
  • Harald Anderson
  • Örjan Strannegård
Opinion Paper

DOI: 10.1007/s00262-013-1458-y

Cite this article as:
Thorén, F.B., Anderson, H. & Strannegård, Ö. Cancer Immunol Immunother (2013) 62: 1547. doi:10.1007/s00262-013-1458-y


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.


ImmunotherapySurvival analysisKaplan–MeierTreatment outcomeLate divergenceStatistical models

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Fredrik B. Thorén
    • 1
    • 2
  • Harald Anderson
    • 3
  • Örjan Strannegård
    • 2
  1. 1.Sahlgrenska Cancer CenterUniversity of GothenburgGöteborgSweden
  2. 2.Department of Infectious DiseasesUniversity of GothenburgGöteborgSweden
  3. 3.Department of Cancer EpidemiologyUniversity of LundLundSweden