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A vast amount of data was collected in the PLCO trial, covering various areas of focus from a variety of sources. The purpose of this section is to break down the data by topic, to explain how it was collected and identify in what files the data can be found.

The bullets to the left are arranged in a loosely chronological order, beginning with questionnaires completed near the start of the trial, through screening, cancer diagnoses and other events of interest, and ending with exit conditions, mortality information and general data cleaning and compilation into files.