For the past 5 decades, the randomized clinical trial (RCT) has been the standard to establish efficacy of new cancer therapies. However, there have been important changes in RCT design and end points since its widespread adoption in the 1970s. In 2008, our group described characteristics of RCTs published in major journals during the era of cytotoxic chemotherapy (1975-2004) for breast, colorectal, and non–small cell lung cancers.
1 During this period, the size of RCTs increased substantially; primary end points shifted from response rate to overall survival (OS); the proportion of trials with a statistically significant difference in favor of the experimental arm doubled (23% to 42%); and, although the magnitude of benefit did not change over time, authors of modern recent RCTs were more likely to strongly endorse the experimental arm as a new standard of care. We also reported a major shift in funding: while government grants supported most RCTs (60%) in the 1970s and 1980s, by the late 1990s and early 2000s, 57% of trials were funded by industry. Finally, our original overview demonstrated sponsorship bias (ie, independent of effect size and statistical significance, industry-funded trials are more likely to be “positive”—defined in the present study as RCTs in which the primary end point has a statistically significant difference in favor of the experimental arm).