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