The Diffusion of Docetaxel in Patients With Metastatic Prostate Cancer

The diffusion of new health care innovations can be inefficient: sometimes treatments with proven benefit permeate slowly through the treatment community, while in other instances, uptake of new drugs occurs prior to definitive evidence (1–3). For such reasons, the study of diffusion has been a major focus of agencies within the National Institutes of Health (NIH) (1). The past several decades have witnessed the introduction of multiple new cancer therapies. The appropriate and rapid adoption of proven new cancer treatments could impact population survival (4,5). Diffusion is the transmission of a new innovation over time within a social system and is driven by perceptions of the innovation, characteristics of adopters, and contextual factors (6,7). Perceptions of an innovation pertain to (often qualitative) assessments of the risks and benefits of the new innovation. Presentation of efficacy findings for a new drug at a scientific conference or in a journal may influence the perception of new treatment benefits (8). Drugs with clearly positive benefit/risk ratios may be taken up immediately into clinical practice. One question is whether adoption follows definitive evidence of a new treatment in a phase III study. Patient characteristics may also influence patterns of chemotherapy use. For instance, older lymphoma and ovarian cancer patients are less likely to receive chemotherapy (2,9). Patients with metastatic prostate cancer typically receive androgen deprivation therapy (ADT) (10), with response durations of 18 to 24 months (11,12). For patients with castration-resistant prostate cancer (CRPC), standard therapy was mitoxantrone combined with prednisone following positive clinical trials in the 1990s, showing that mitoxantrone provided palliative relief but no survival benefit (13,14). Docetaxel (Taxotere, Sanofi-Aventis) received US Food and Drug Administration (FDA) approval for treatment of advanced breast and lung cancers in the late 1990s. Thereafter in 2004, docetaxel was shown to provide both pain relief and improved survival in CRPC, reducing the risk of death by about 20%, and, with concurrent FDA approval, became new standard care (15,16). In this analysis, we hypothesized that docetaxel uptake followed definitive evidence of docetaxel efficacy in a phase III trial, and that diffusion was slower for disadvantaged patient populations.