The PLCO Biorepository stores approximately 2.9 million biologic specimens collected from PLCO participants. Some of characteristics that make PLCO samples particularly valuable for etiologic and early marker research are:

  • Large number of cases and controls available for common cancers
  • Specimens collected under a uniform collection and storage protocol
  • Serial specimens collected annually for up to 6 rounds for participants in the intervention arm
  • Specimens collected before cancer diagnosis
  • Lifestyle and dietary data collected prior to cancer diagnosis
  • Diagnosis and treatment data available for the P, L, C, O cancers
  • Diagnosis and treatment data available for colorectal adenomas
  • Diagnosis data available for other cancers
  • Patients consented for research in cancer and other diseases common in this age group

PLCO biospecimens are available to all qualified researchers through the EEMS program. For more information on how to submit a proposal for access to PLCO biospecimen resources, please visit

Biospecimens available for research include:

Fractionated Blood Samples

At each of six screening rounds, screening arm participants provided blood samples for etiologic and early marker research. Amounts collected and fractioning protocols vary by study year. Serum samples are stored for all study years. Plasma, red blood cells, and DNA (buffy coat) fractions are stored for some years.

Cryopreserved Whole Blood

Cryopreserved whole blood is stored from blood collections in the fourth screening round. The samples contain viable lymphocytes which can be used directly for in vitro studies and are suitable for EBV transformation to cell lines.

Buccal Cells

Buccal cells were collected from participants in the control arm of the trial. These serve primarily as a DNA resource, although amounts are limited.