29 August 2016 - Interpretation of oncology clinical trial data are not always straightforward or consistent. Similar trial results with disparate interventions may be interpreted differently by the oncology community.

In a commentary published in the Journal of Clinical Oncology, Gywall & Prasad state that one of the main reasons for this discrepancy is the debate regarding what is the appropriate outcome for demonstration of the efficacy of new cancer medicines. There is no doubt that overall survival (OS) is the best parameter to judge the utility of any intervention, and it is free from bias in ascertainment and measurement; but for conditions with few treatment options and dire outcomes, the need for new agents is high and the oncology community sometimes settles on a surrogate outcome that, in many cases, is progression-free survival (PFS).

They say that It is easy to understand why PFS is favored among the researchers: It occurs early and is not influenced by postprogression therapy. At the same time, it would make little sense to have an agent that reduces chances of dying of cancer but increases off-target deaths; hence, the need for verification of OS. Phase III trials that report on significant PFS benefits without OS prolongation become the apples of discord in the oncology community. In this commentary, we present three examples from lung, ovarian, and breast cancers and demonstrate how the oncology community interprets similar data differently. Finally, we take our best guess as to why this phenomenon happens.

Read Journal of Clinical Oncology Commentary