Design of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

The objectives of the Prostate, Lung, Colorectal and Ovarian Cancer Screeni ng Trial are to determine in screenees ages 55-74 at entry whether screenin g with flexible sigmoidoscopy (60-cm sigmoidoscope) can reduce mortality fr om colorectal cancer, whether screening with chest X-ray can reduce mortali ty from lung cancer, whether screening men with digital rectal examination (DRE) plus serum prostate-specific antigen (PSA) can reduce mortality from prostate cancer, and whether screening women with CA125 and transvaginal ul trasound (TVU) can reduce mortality from ovarian cancer. Secondary objectiv es are to assess screening variables other than mortality for each of the i nterventions including sensitivity, specificity, and positive predictive va lue; to assess incidence, stage, and survival of cancer cases; and to inves tigate biologic and/or prognostic characterizations of tumor tissue and bio chemical products as intermediate endpoints. The design is a multicenter, t wo-armed, randomized trial with 37,000 females and 37,000 males in each of the two arms. In the intervention arm, the PSA and CA125 tests are performe d at entry, then annually for 5 years. The DRE, TW, and chest X-ray exams a re performed at entry and then annually for 3 years. Sigmoidoscopy is perfo rmed at entry and then at the 5-year point. Participants in the control arm follow their usual medical care practices. Participants will be followed f or at least 13 years from randomization to ascertain all cancers of the pro state, lung, colorectum, and ovary, as well as deaths from all causes. A pi lot phase was undertaken to assess the randomization, screening, and data c ollection procedures of the trial and to estimate design parameters such as compliance and contamination levels. This paper describes eligibility, con sent, and other design features of the trial, randomization and screening p rocedures, and an outline of the follow-up procedures. Sample-size calculat ions are reported, and a data analysis plan is presented. Control Clin Tria ls 2000;21:273S-309S (C) Elsevier Science Inc. 2000.