Cancer can exhibit relentless growth and relapse because of the enhanced protection of its chromosome ends. Dr. Uri Tabori is a world expert in telomeres – the protective caps at the ends of DNA. Dr. Tabori has discovered that telomeres are maintained by a section of DNA called THOR. THOR methylation allows cancers to become immortal and cause tumour relapse. The team has recently shown in several childhood and adult cancers that THOR can predict which tumours will recur and that removal of THOR methylation stops cancer’s ability to recur. In this project, Dr. Tabori and his team will test whether the presence of THOR in a simple blood or urine test could be used to detect cancer early, predict relapse and survival, and identify new drugs to prevent relapse. The impact of this proposal is severalfold: THOR is a simple and cheap assay which can be done in most clinical laboratories worldwide, and if it can predict outcome, testing could be routinely done. The ability to find cancer in a simple blood and urine test before it appears can enable us to prevent initial cancer and to detect and treat early relapse. This important research could lead to new diagnostic and treatment strategies with a focus on brain, prostate and bladder cancers.