Do extended recruitment efforts minimize attrition but not necessarily bias?
Extended recruitment efforts appeared justified in terms of response maximization. However, enhanced response proportions may not necessarily minimize bias. In our analysis, aiming for a high-response proportion in terms of health-related indicators had no effect, because late respondents did not differ from early respondents.
Patient-derived xenografts allow detailed investigation of therapy-related markers and their dynamic regulation in a well-standardised and clinically related way. As a consequence of our investigations, we regard multidrug resistance to be a multifactorial phenomenon, in which more factors than the markers analysed by the present study may be involved.