Comparison of outcomes of phase II trials (P2Ts) and subsequent randomized control trials (RCTs) using identical therapeutic regimens. M. I. Zia, L. L. Siu, G. R. Pond, E. X. Chen; Princess Margaret Hospital, Toronto, ON, Canada Abstract: Background: RCTs are cornerstones of evidence-based clinical oncology practice. RCTs are often based on promising results from P2Ts. However, it is not clear whether these results translate into positive RCTs. Methods: We searched for all RCTs of chemotherapy or combined chemotherapy and radiation therapy in solid malignancies published in the English language literature from July 1998 to June 2003. RCTs of neoadjuvant or adjuvant therapy were excluded. Eligible RCTs were reviewed to identify preceding P2Ts. To be included in the analysis, P2Ts and RCTs must have used identical therapeutic regimens in same patient populations. RCTs were considered to be positive if the experimental regimen was significantly better than the control in terms of primary endpoints. Response rates from both P2Ts and RCTs were retrieved. The following variables were also collected from P2Ts: number of patients, whether P2Ts were randomized and/or multi-centered, and the impact factor of the journal in which a P2T was published. Logistic regressions were performed to evaluate influences of these variables on outcomes of subsequent RCTs. Results: Of 181 RCTs identified, 47 used same therapeutic regimens as those in 59 preceding P2Ts. Ten (21.3%) of 47 RCTs are considered positive RCTs. Response rates were at least equal to those in P2Ts in only 9 (19.1%) RCTs. The mean difference in response rates between P2Ts and RCTs was 13% (absolute difference, range: 0 - 37.8%). The only statistically significant predictor of a positive RCT is the number of patients entered in preceding P2Ts. For every 10-patient increment in the size of a P2T, the odds of observing a positive RCT increases by 1.22 times (p = 0.042). Conclusions: Promising results from P2Ts frequently do not translate into positive RCTs. Response rates in most RCTs are lower than those in preceding P2Ts. The only significant predictor of a positive RCT is the number of patients in preceding P2Ts. Abstract No: 6000 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.