Questions about the efficacy of screening are key to impacting cancer morbidity and mortality. The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial was designed by the National Cancer Institute in the early 1990s to address these questions for the 4 cancers that make up its name.

• Westat has served as the coordinating center for PLCO Cancer Screening Trial since its inception. The trial originally recruited more than 150,000 people aged 50 to 74 at 10 clinical centers, randomized them to a screening or control arm, and continues to follow them longitudinally, collecting data on cancer incidence and mortality.
• After 20 years of data collection at each clinical center, the study has moved to centralized followup, carried out by Westat.
• Westat staff contributed to the report, which appeared in the New England Journal of Medicine,  about the results of screening with flexible sigmoidoscopy for colon cancer. Screening was associated with a significant decrease in colon cancer incidence and mortality.
• Westat is continuing active data collection with PLCO participants, physicians, and medical records and pathology departments through the Central Data Collection Center (CDCC). The CDCC also conducts passive data collection activities such as submissions to state tumor registries for data linkage and National Death Index searches.

• PLCO has already helped researchers answer important questions about the early detection value of PSA testing for prostate cancer, chest X-ray for lung cancer, flexible sigmoidoscopy for colon cancer, and CA125 and ultrasound for ovarian cancer.