Clinical trials have strict eligibility criteria, potentially limiting external validity. However, while often discussed this has seldom been explored, particularly across cancer types and at variable time frames posttrial completion. We examined comprehensive registry data (January 2014 to June 2019) for standard first-line treatments for metastatic colorectal cancer (CRC), advanced pancreatic cancer (PC), metastatic HER2-amplified breast cancer (BC) and castrate-resistant prostate cancer (CaP). Registry patient characteristics and outcomes were compared to the practice-changing trial. Registry patients were older than the matched trial cohort by a median of 2-6 years (all P = <.01) for the CRC, BC and PC cohorts. The proportion of Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1 patients was lower for CRC (94.1% vs 99.2%, P = .001) and BC (94.9% vs 99.3%, P = .001). Progression-free survival (PFS) for registry patients was similar to the trial patients or significantly longer (CaP, Hazard Ratio [HR] = 0.65, P = <.001). Overall survival (OS) was also similar or significantly longer (CaP, HR 0.49, P = <.001). In conclusion, despite real-world patients sometimes being older or having inferior PS to trial cohorts, the survival outcomes achieved were consistently equal or superior to those reported for the same treatment in the trial. We suggest that this is potentially due to optimised use of each treatment over time, improved multidisciplinary care and increased postprogression options. We can reassure clinicians and patients that outcomes matching or exceeding those reported in trials are possible. The potential for survival gains over time should routinely be factored into future trial statistical plans.
Keywords: efficacy-effectiveness gap; metastatic cancer; real-world outcomes.
© 2021 Union for International Cancer Control.