In 2015 we established the Lymphoma Epidemiology of Outcomes (LEO) Cohort. [NCT 02736357].  The goal of the LEO study is to build and maintain a large and diverse cohort of non-Hodgkin lymphoma (NHL) patients to support a broad research agenda aimed at identifying new clinical, epidemiologic, genetic, tumor, and treatment factors that influence outcome and the overall survivorship experience.

The LEO cohort opened enrollment in July 2015, and through May 2020 enrolled 7748 newly diagnosed NHL patients recruited from 8 LEO centers (Cornell, Emory, Mayo Clinic, MD Anderson, University of Iowa, University of Miami, University of Rochester, Washington University).  The LEO cohort expanded an ongoing cohort of 4905 NHL patients that was established in 2002 as the Molecular Epidemiology Resource (MER) in the University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellence (SPORE) program.  The MER cohort closed enrollment when LEO was started on July 1, 2015, and became a part of LEO as the LEO-MER subcohort.  When combined together, the 12,653 participants make LEO the largest prospective cohort of NHL survivors in the world.  In 2021, LEO was renewed through 2026 for follow-up of all participants as well as additional targeted recruitment as LEO Phase 2 [NCT 04996706].

Once enrolled into LEO, participants complete questionnaires on their health history, lifestyle, quality of life, and other factors.  The LEO study team collects clinical, pathology and treatment data from medical records.  Participants also provide a blood sample, which is processed and stored as DNA, plasma and serum in the LEO biorepository.  LEO study pathologists review and classify diagnostic tumor tissue, some of which is stored in the LEO biorepository.  The LEO team then follows all participants over time to collect updated medical and lifestyle data, quality of life, new treatments, and disease outcomes.