Evaluation of the representativeness and generalizability of Japanese clinical trials for localized rectal/colon cancer: Comparing participants in the Japan Clinical Oncology Group study with patients in Japanese registries

Eur J Surg Oncol. 2020 Sep;46(9):1642-1648. doi: 10.1016/j.ejso.2020.04.005. Epub 2020 Apr 18.


Introduction: It is unclear if clinical trial results including patients who meet trial eligibility criteria, are applicable to actual patients in daily practice (generalizability). Moreover, the extent to which are trial participants different from patients seen in daily practice (representativeness) is also unclear. The aim of this study was to evaluate the representativeness of the patients registered in randomized clinical trials to patients in daily practice and examine the generalizability of trial results to daily practice.

Methods: We compared the results of surgical trials conducted by the Japan Clinical Oncology Group with data from two Japanese cancer registries, representing patients seen in daily practice. We compared overall survival (OS) between trial participants and registry patients to evaluate representativeness of trial participants. We then compared the OS of registry patients who received open surgery (OP) and laparoscopic surgery (LAP) to evaluate the generalizability of trial results.

Results: We analyzed 3051 patients (701 in JCOG0212, 2350 registry patients) with rectal cancer and 3116 patients (1057 in JCOG0404, 2059 registry patients) with colon cancer. Trial participants tended to possess lower clinical stages. Multivariable analyses revealed registry patients with significantly worse survival compared with trial participants. The hazard ratio of LAP to OP among registry patients was 0.305 (95% CI; 0.048-2.188), which did not meet the prespecified generalizability criteria of 0.9.

Conclusions: Our results failed to ensure either the representativeness or generalizability of clinical trial results, compared to daily practice. Careful considerations are required when applying trial results to patients in daily practice.

Keywords: Clinical trials; Colorectal cancer; Daily practice; Generalizability; Representativeness.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Colectomy / methods*
  • Colonic Neoplasms / pathology
  • Colonic Neoplasms / surgery*
  • Equivalence Trials as Topic
  • Female
  • Humans
  • Japan
  • Laparoscopy / methods*
  • Lymph Node Excision / methods*
  • Male
  • Mesentery / surgery
  • Middle Aged
  • Multivariate Analysis
  • Neoplasm Staging
  • Patient Selection
  • Proctectomy / methods*
  • Proportional Hazards Models
  • Randomized Controlled Trials as Topic
  • Rectal Neoplasms / pathology
  • Rectal Neoplasms / surgery*
  • Registries
  • Research Subjects
  • Survival Rate
  • Young Adult