Centralized blood processing for the selenium and vitamin E cancer prevention trial: effects of delayed processing on carotenoids, tocopherols, insulin-like growth factor-I, insulin-like growth factor binding protein 3, steroid hormones, and lymphocyte viability.

This experiment examined the effects of delays in separation and freezing of whole blood components on analytes of interest in studies of prostate cancer prevention, in order to evaluate the feasibility of centralized processing of blood for the multisite Selenium and Vitamin E Cancer Prevention Trial. Blood from 40 healthy men was subjected to four treatment protocols, allowing the contrast of immediate processing to delays of 32, 72, and 144 hours. At 32 hours, simulating refrigerated storage and overnight shipping, there was a 2.9% decrease (95% confidence interval, 0.7-5.1) in insulin-like growth factor-I (IGF-I) but no significant change in carotenoids, tocopherols, testosterone, 3alpha-androstanediol glucuronide (AAG), sex hormone-binding globulin (SHBG) or insulin-like growth factor binding protein 3 (IGFBP3). A 144-hour processing delay, simulating weekend blood collection or shipping delay, resulted in significant changes in gamma-tocopherol (-1.5%), IGF-I (-5.7%), IGFBP3 (-2.9%), SHBG (-4.0%), testosterone (+4.7%), and AAG (+5.5%). The rank-order and intraclass correlations between analytes from blood processed immediately and those subjected to delayed processing were 0.96 or higher for carotenoids, tocopherols, AAG, and SHBG, and between 0.87 and 0.95 for IGF-I, IGFBP3, and testosterone. A 32-hour delay decreased lymphocyte viability from 82.5% to 75.0% (P = 0.45), but a 72-hour delay decreased viability to 36.8% (P < 0.001). Overnight shipping and centralized processing is an acceptable approach to blood collection in large multisite trials examining the cancer-related measures proposed in the Selenium and Vitamin E Cancer Prevention Trial. Longer processing delays, however, have small but statistically significant effects on many analytes and substantially decrease lymphocyte viability.