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Welcome to the Cancer Data Access System

The Cancer Data Access System (CDAS) is a submission and tracking system for the use of data from the National Lung Screening Trial (NLST) and the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

Interested investigators can register with CDAS and request access to data from either screening trial. All requests are reviewed by NCI trial leadership. Upon approval, investigators will be granted access to the requested data for a limited period.

CDAS provides extensive documentation for each trial including a summary of the trial, a description of the data collected, and a searchable list of research projects and publications.



The National Lung Screening Trial compared two ways of detecting lung cancer: low-dose helical computed tomography (CT) and standard chest X-ray. Both chest X-rays and low-dose helical CT scans have been used to find lung cancer early, but the effects of these screening techniques on lung cancer mortality rates had not been determined. NLST enrolled approximately 54,000 current or former heavy smokers from 33 sites and coordinating centers across the United States.

Information about NLST and available data and documentation



The Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial is a large scale, randomized study to determine whether certain screening tests will reduce the number of deaths from these cancers. PLCO is being conducted at ten sites, geographically and demographically disparate, around the U.S. The Trial enrolled approximately 155,000 male and female participants between the ages of 55 and 74 from 1993 to 2001.

Information about PLCO and available data and documentation

The CDAS development team would like to acknowledge the National Heart, Lung, and Blood Institute and its BioLINCC Program for the programming code used in the implementation of this website. The CDAS code was based on the BioLINCC framework, which shares many of the same advanced features and a well-defined yet flexible workflow for request submission and fulfillment.