Etiologic and early marker studies in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, which is randomizing 74,000 screening arm participants (37,000 men, 37,000 women; a ges 55-74) and an equal number of nonscreened controls, is a unique setting for the investigation of the etiology of cancer and other diseases and for the evaluation of potential molecular markers of early disease. At entry, baseline information is collected by questionnaire on dietary intake, tobac co and alcohol use, reproductive history (for women), family history of can cer, use of selected drugs, and other selected risk factors. Blood samples collected at the baseline screening exam are aliquoted to serum, plasma, re d blood cell, and buffy coat fractions. At the next two annual screening vi sits, serum samples are collected. At the third annual reexamination, cryop reserved whole blood is obtained, in addition to serum, plasma, red blood c ell, and buffy coat fractions. At the fourth and fifth years, serum, plasma , and buffy coat are collected. All blood samples are shipped to a central repository for long-term storage at -70 degreesC. Dietary questionnaires an d buccal cells for DNA analysis are obtained from nonscreened controls. Can cer cases are identified through annual follow-up questionnaires, and all d eaths are identified through vital status tracing mechanisms. Procedures ar e being developed to obtain archival pathologic material for selected cases of cancer and related diseases. Initial investigations are focusing on the etiology of colorectal cancer and on the operative characteristics of test s for the early detection of colorectal and prostate cancer. Control Clin T rials 2000;21:349S-355S (C) Elsevier Science Inc. 2000.