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Overcoming challenges in designing and implementing a phase II randomized controlled trial using a presurgical model to test a dietary intervention in prostate cancer

Division of Cancer Prevention & Control/Department of Behavioral Science, MD Anderson Cancer Center, Houston, TX USA, wdemarkw{at}mdanderson.org

Stephen L George

Department of Biostatistics, Duke University Medical Center (DUMC), Durham, NC, USA

Boyd R Switzer

Department of Nutrition, University of North Carolina, Chapel Hill, NC, USA

Denise C Snyder

Duke School of Nursing, Durham, NC, USA

John F Madden

Department of Pathology, DUMC, Durham, NC, USA

Thomas J Polascik

Department of Surgery, DUMC, Durham, NC, USA

Mack T Ruffin, IV

Department of Family Medicine and University of Michigan Community Clinical Oncology Program Research Base, University of Michigan, Ann Arbor, MI, USA

Robin T Vollmer

Department of Pathology, DUMC, Durham, NC, USA, Durham Veterans Administration Medical Center, Durham, NC, USA

Background: The time between the diagnosis of cancer and a planned definitive surgical procedure offers a strong and direct approach for assessing the impact of interventions (including lifestyle interventions) on the biology of the target tissue and the tumor. Despite the many strengths of presurgical models, there are practical issues and challenges that arise when using this approach.

Purpose:/Methods We recently completed an NIH-funded phase II trial that utilized a presurgical model in testing the comparative effects of flaxseed supplementation and/or dietary fat restriction on the biology and biomarkers associated with prostatic carcinoma. Herein, we report the rationale for our original design, discuss modifications in strategy, and relay experiences in implementing this trial related to the following topics: (1) subject accrual; (2) subject retention; (3) intervention delivery; and (4) retrieval and completion rates regarding the collection of paraffin-embedded and fresh frozen prostate tissue, blood, urine, ejaculate, anthropometric measures and survey data.

Results: This trial achieved its accrual target, i.e., a racially-representative (70% white, 30% minority) sample of 161 participants, low rates of attrition (7%); and collection rates that exceeded 90% for almost all biospecimens and survey data. While the experience gained from pilot studies was invaluable in designing this trial, the complexity introduced by the collection of several biospecimens, inclusion of a team of pathologists (to provide validated readings), and shifts in practice patterns related to prostatectomy, made it necessary to revise our protocol; lessons from our experiences are offered within this article.

Conclusions: While our experience specifically relates to the implementation of a presurgical model-based trial in prostate cancer aimed at testing flaxseed-supplemented and fat-restricted diets, many of the lessons learned have broad application to trials that utilize a presurgical model or dietary modification within various cancer populations. Clinical Trials 2008; 5: 262—272. http://ctj.sagepub.com

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