Solid organ transplantation provides life-saving therapy for patients with end-stage organ disease. Although transplant outcomes have improved dramatically over time, substantial morbidity results from chronic immunosuppressive therapy administered to prevent graft rejection. In large part due to this immunosuppression, transplant recipients have an elevated risk of cancer that is 2-4 times higher overall than the risk seen in the general population.
Much of this increased risk is related to a high risk for cancers caused by viral infections. The most common of these virus-related cancers is non-Hodgkin lymphoma, which is frequently caused by Epstein Barr virus. Other virus-related cancers include Kaposi sarcoma (caused by human herpesvirus 8); cancers of the cervix, vagina, vulva, penis, anus, and oral cavity (caused by human papillomavirus); and liver cancer (caused by hepatitis C and B viruses). Certain other malignancies, such as cancers of the lung, kidney, and thyroid, are also increased in transplant recipients. In addition, skin cancers (especially squamous cell and basal cell carcinomas, but also melanoma) occur at an elevated frequency.
For public health purposes, both organ transplantation and cancer are monitored by U.S. federal and state agencies. Information on all U.S. transplant candidates, recipients, and donors is provided by transplant centers and organ procurement organizations to the Scientific Registry of Transplant Recipients (SRTR). Cancers are reportable by clinicians and healthcare facilities to state and regional cancer registries.
The Transplant Cancer Match Study uses electronically linked data from the SRTR and cancer registries to study the epidemiology of cancer in the U.S. transplant population. This study is the largest study of cancer risk in solid organ transplant recipients in the world. Participating cancer registries collectively provide data on approximately 48% of the U.S. transplant population through 2014, or approximately 291,000 transplant recipients. The study captures recipients of all organ types in each participating state or metropolitan region, so the included population is representative of the overall U.S. transplant population. Ongoing registry linkages provide updated data to monitor cancer trends and to expand the study into new geographic regions of the U.S.
A major goal of the Transplant Cancer Match Study is to determine the overall pattern of cancer in transplant recipients and identify key risk factors for individual cancer types. These findings will yield information on the role of the immune system in the development of cancer. In addition, a better understanding of cancer risk factors will help clarify the contributions of medical conditions, chronic viral infections, and specific medications.
While cancer risk is elevated in transplant recipients, the benefits of organ transplantation for people with end-stage organ disease far outweigh this risk. Nonetheless, HRSA and the SRTR continuously monitor transplant outcomes to maximize the safety of solid organ transplantation. Because cancer is an important adverse outcome of transplantation, findings from the Transplant Cancer Match Study can help identify opportunities to prevent or screen for cancer, and optimize survival following a cancer diagnosis.