Solid organ transplantation is life-saving for patients with organ failure. However, transplant patients are known to be at a higher risk of developing cancer because their immune system needs to be suppressed. This study will use information from the CORR registry - a registry of all patients having a solid organ transplant in Ontario linked to information from the Ontario Cancer Registry, a registry of people developing cancer in Ontario. We are interested in evaluating if transplant patients develop cancer over time, if some cancers occur more frequently, and in patients who develop cancer, if the outcomes of these patients are worse than non-transplant patients. Very little is known about how cancer is treated in transplant patients and we will perform a review of the medical charts of 600 transplant patients with cancer and 600 non-transplant patients with cancer (control patients) to help determine if there are differences in how cancer is detected and/or treated in transplant vs. control patients. If we identify differences that have an impact on survival, we can then develop strategies to improve outcome. For example, if cancer tends to be diagnosed late in transplant patients a greater focus on screening and early detection of cancer would be an important strategy to improve cancer survival in this group of patients. We will gather together experts in the field of cancer care and transplantation as well as groups representing transplant and cancer patients. These individuals and organizations have input into our study so that the results of our research are maximally useful and have an impact.