The objectives of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial
are to determine in screenees ages 55-74 at entry whether screening with flexible
sigmoidoscopy (60-cm sigmoidoscope) can reduce mortality from colorectal cancer, whether
screening with chest X-ray can reduce mortality 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 ultrasound (TVU) can reduce mortality from ovarian cancer. Secondary
objectives are to assess screening variables other than mortality for each of the
interventions including sensitivity, specificity, and positive predictive value; to
assess incidence, stage, and survival of cancer cases; and to investigate biologic
and/or prognostic characterizations of tumor tissue and biochemical products as intermediate
endpoints. The design is a multicenter, two-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 performed at entry, then annually for 5 years. The DRE, TVU, and chest X-ray
exams are performed at entry and then annually for 3 years. Sigmoidoscopy is performed
at entry and then at the 5-year point. Participants in the control arm follow their
usual medical care practices. Participants will be followed for at least 13 years
from randomization to ascertain all cancers of the prostate, lung, colorectum, and
ovary, as well as deaths from all causes. A pilot phase was undertaken to assess the
randomization, screening, and data collection procedures of the trial and to estimate
design parameters such as compliance and contamination levels. This paper describes
eligibility, consent, and other design features of the trial, randomization and screening
procedures, and an outline of the follow-up procedures. Sample-size calculations are
reported, and a data analysis plan is presented.