Same Data; Different Interpretations
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. One of the main reasons for this discrepancy is the debate regarding what is the appropriate end point for demonstration of efficacy of cancer drugs. 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 measurement1; 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 end point that, in many cases, is progression-free survival (PFS).2 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.
We cannot also ignore the deep issues beyond clinical data that result in discrepancies in cancer care, such as politics, emotional overlay, lobbying, and advocacy of support groups. Although we explore three instances of discrepancies in the treatment of three similar cancer settings in this paper, many discrepancies exist in cancer care. When bevacizumab was revoked for breast cancer, support groups and patient advocates protested against the decision, but when 131I-tositumomab was withdrawn from marketing, it died silently. Thus, our attitudes toward cancer care are multifactorial. As oncologists, however, we should push for uniformity in the interpretation of clinical trial results and try to achieve as much consistency in our practice as possible. Consistency would be a virtue for cancer care.