Identifying barriers to accrual in radiation oncology randomized trials

J. M. Laba, S. Senan, D. Schellenberg, S. Harrow, L. Mulroy, S. Senthi, A. Swaminath, N. Kopek, J. R. Pantarotto, L. Pan, A. Pearce, A. Warner, A. V. Louie, David A. Palma

Research output: Contribution to journalArticleResearchpeer-review

11 Citations (Scopus)


Background Data about factors driving accrual to radiation oncology trials are limited. In oncology, 30%–40% of trials are considered unsuccessful, many because of poor accrual. The goal of the present study was to inform the design of future trials by evaluating the effects of institutional, clinician, and patient factors on accrual rates to a randomized radiation oncology trial. Methods Investigators participating in sabr-comet (NCT01446744), a randomized phase ii trial open in Canada, Europe, and Australia that is evaluating the role of stereotactic ablative radiotherapy (SABR) in oligometastatic disease, were invited to complete a survey about factors affecting accrual. Institutional ethics approval was obtained. The primary endpoint was the annual accrual rate per institution. Univariable and multivariable linear regression analyses were used to identify factors predictive of annual accrual rates. Results On univariable linear regression analysis, off-trial availability of SABR (p = 0.014) and equipoise of the referring physician (p = 0.014) were found to be predictive of annual accrual rates. The annual accrual rates were lower when centres offered sabr for oligometastases off-trial (median: 3.7 patients vs. 8.4 patients enrolled) and when referring physicians felt that, compared with having equipoise, sabr was beneficial (median: 4.8 patients vs. 8.4 patients enrolled). Multivariable analysis identified perceived level of equipoise of the referring physician to be predictive of the annual accrual rate (p = 0.023). Conclusions The level of equipoise of referring physicians might play a key role in accrual to radiation oncology randomized controlled trials. Efforts to communicate with and educate referring physicians might therefore be beneficial for improving trial accrual rates.

Original languageEnglish
Pages (from-to)e524-e530
Number of pages7
JournalCurrent Oncology
Issue number6
Publication statusPublished - 20 Dec 2017
Externally publishedYes


  • Accrual
  • Clinical trials
  • Oligometastases
  • Stereotactic radiotherapy

Cite this