Sergio A. Acuna, MD, PhD Student – Clinical Epidemiology and Health Care Research Institute of Health Policy Management and Education
Although solid organ transplant recipients (SOTRs) are at greater risk of developing some cancers than the general population, because they are also at increased risk of mortality from non-cancer causes, the effect of transplantation on cancer mortality was unclear. We sought to determine the risk of cancer mortality in SOTRs using a population-based cohort study of patients who underwent solid-organ transplantation in Ontario, Canada, between 1991 and 2010. SOTRs were identified using the national transplant register and linked to the provincial cancer registry and administrative databases. Mortality was determined from death certificates using the Office of the Registrar General of Ontario death database (ORGD) and verified using Ontario Cancer Registry (OCR) cause of death. In order to determine whether cancer deaths were caused by a post-transplant de novo malignant neoplasm or the recurrence of a pre-transplant malignant neoplasm, the cause of death was matched to cancer diagnosis information from the OCR.
We found that cancer mortality in SOTRs was significantly elevated compared with the Ontario population (SMR, 2.84 [95%CI, 2.61-3.07]), and that although the majority of cancer-related deaths were secondary to post-transplant de novo malignant neoplasms (n = 411 [68%]), recurrent malignant neoplasms were responsible for 21% (n = 127). Most of the cancer deaths associated with pre-transplant malignant neoplasms were caused by malignant neoplasms that were the indication for transplantation (n = 98 [77%]).
Few jurisdictions could replicate the population-based nature of our study. Our ability to link the provincial cancer registry with the transplant registry was key for successful completion of this study. The few studies that have previously explored cancer mortality after transplantation report disparate findings. An attempt at determining cancer mortality risk in American kidney transplant recipients resulted in contradictory findings given the limited availability of mortality data to be linked in the US. This study used the mortality data from the United States Renal Data System, which had a 40% of missing causes of death. Our investigation uses the unique resources of the Institute for Clinical Evaluative Science in Ontario and its population-based data is particularly powerful and ensures generalizability. The large number of SOTR included, the comprehensive availability of the cause of death for all SOTR, and the ability to link to the Ontario cancer registry allow us to conclusively ascertain the risk of cancer mortality in this population. Additionally, this study is the first to compare cancer mortality by type of SOTR and that evaluates recurrent versus post-transplant de novo cancer deaths. Recognizing the increased risk of cancer mortality among transplant recipients is critical to optimize cancer screening and treatment in this population.
Read Full Article (The abstract below is from The JAMA Network)
Abstract
Importance Solid-organ transplant recipients (SOTRs) are at greater risk of developing some cancers than the general population; however, because they are also at increased risk of mortality from noncancer causes, the effect of transplantation on cancer mortality is unclear.
Objective To describe cancer mortality in SOTRs and to assess whether SOTRs are at increased risk of cancer mortality compared with the general population.
Design, Setting, and Participants Population-based cohort study of patients who underwent solid-organ transplantation in Ontario, Canada, between 1991 and 2010 with 85 557 person-years of follow-up through December 31, 2011. Solid-organ transplantation was identified using the national transplant register and linked to the provincial cancer registry and administrative databases. The analysis was conducted between November 2013 and February 2015.
Exposure Solid-organ transplantation.
Main Outcomes and Measures Cancer mortality for SOTRs was compared with that of the general population using standardized mortality ratios (SMRs). Mortality and cause of death were ascertained by record linkage between the Canadian Organ Replacement Register, the Ontario Cancer Registry, and the Office of the Registrar General of Ontario death database.
Results A total of 11 061 SOTRs were identified, including 6516 kidney, 2606 liver, 929 heart, and 705 lung transplantations. Recipients had a median (interquartile range) age of 49 (37-58) years, and 4004 (36.2%) were women. Of 3068 deaths, 603 (20%) were cancer related. Cancer mortality in SOTRs was significantly elevated compared with the Ontario population (SMR, 2.84 [95% CI, 2.61-3.07]). The risk remained elevated when patients with pretransplant malignant neoplasms (n = 1124) were excluded (SMR, 1.93 [95% CI, 1.75-2.13]). The increased risk was observed irrespective of transplanted organ. The SMR for cancer death after solid-organ transplantation was higher in children (SMR, 84.61 [95% CI, 52.00-128.40]) and lower in patients older than 60 years (SMR, 1.88 [95% CI, 1.62-2.18]) but remained elevated compared with the general population at all ages.
Conclusions and Relevance Cancer death rate in SOTRs was increased compared with that expected in the general population; cancer was the second leading cause of death in these patients. Advances in prevention, clinical surveillance, and cancer treatment modalities for SOTRs are needed to reduce the burden of cancer mortality in this population.
The opinions expressed in this article are those of the authors and may not represent the official positions of NAACCR.
