Statistical controversies in clinical research: basket trials, umbrella trials, and other master protocols: a review and examples

In recent years, cancers once viewed as relatively homogeneous in terms of organ location and treatment strategy are now better understood to be increasingly heterogeneous across biomarker and genetically defined patient subgroups. This has produced a shift toward development of biomarker-targeted agents during a time when funding for cancer research has been limited; as a result, the need for improved operational efficiency in studying many agent-and-target combinations in parallel has emerged. Platform trials, basket trials, and umbrella trials are new approaches to clinical research driven by this need for enhanced efficiency in the modern era of increasingly specific cancer subpopulations and decreased resources to study treatments for individual cancer subtypes in a traditional way. In this review, we provide an overview of these new types of clinical trial designs, including discussions of motivation for their use, recommended terminology, examples, and challenges encountered in their application.

Survival following early-stage colon cancer: an ACCENT-based comparison of patients versus a matched international general population†

BACKGROUND

Post-treatment survival experience of early colon cancer (CC) patients is well described in the literature, which states that cure is probable for some patients. However, comparisons of treated patients' survival versus that expected from a matched general population (MGP) are limited.

PATIENTS AND METHODS

A total of 32 745 patients from 25 randomized adjuvant trials conducted from 1977 to 2012 in 41 countries were pooled. Observed long-term survival of these patients was compared with expected survival matched on sex, age, country, and year, both overall and by stage (II and III), sex, treatment [surgery, 5-fluorouracil (5-FU), 5-FU + oxaliplatin], age (<70 and 70+), enrollment year (pre/post 2000), and recurrence (yes/no). Comparisons were made at randomization and repeated conditional on survival to 1, 2, 3, and 5 years. CC and MGP equivalence was tested, and observed Kaplan-Meier survival rates compared with expected MGP rates 3 years out from each landmark. Analyses were also repeated in patients without recurrence.

RESULTS

Within most cohorts, long-term survival of CC patients remained statistically worse than the MGP, though conditional survival generally improved over time. Among those surviving 5 years, stage II, oxaliplatin-treated, elderly, and recurrence-free patients achieved subsequent 3-year survival rates within 5% of the MGP, with recurrence-free patients achieving equivalence.

CONCLUSIONS

Conditional on survival to 5 years, long-term survival of most CC patients on clinical trials remains modestly poorer than an MGP, but achieves MGP levels in some subgroups. These findings emphasize the need for access to quality care and improved treatment and follow-up strategies.