BERKELEY, CA (UroToday.com) -
Excellent short- and long-term patient and graft survivals in recent decades have drawn increasing attention to long-term complications of transplantation, including malignancies. Urinary tract cancers are the third most common cancers in renal transplant recipients (RTX). This study examined the impact of dialysis duration and native renal cyst(s) (NRC) on the development of renal cell carcinoma (RCC) among all 1,132 RTX followed-up at the Singapore General Hospital from 1995 to July 2007.
From 1995, abdominal ultrasonography (US) was planned within 1-month of transplant, then every 5 years, or 2 years if renal cysts developed. Suspicious lesions were further investigated with computed tomography and/or magnetic resonance imaging, followed by the appropriate treatment. Patients transplanted prior to 1995, or those transferring from other transplant centers underwent their first US at the earliest opportunity. For all transplants, including re-transplants, duration of dialysis was taken from the date of first dialysis. The study population was evaluated for the presence of risk factors for RCC by examining the presence or absence of NRC, timing of onset of NRC in relation to transplantation, duration of dialysis pre-transplant and interval post-transplant. Based on presence and time of development of NRC, RTX were grouped into those with no (No-NRC), new (N
ew-NRC), pre-existing (Pre-NRC) and time-indeterminate NRC (TI-NRC). Ten asymptomatic RTX were diagnosed with RCC at a median of 5.8 years post-transplant and had 5-year graft and patient survivals of 90% and 100% respectively, following appropriate therapy, which was comparable to survival rates in RCC patients in the general population. RCC occurred only in Pre-NRC and TI-NRC who had significantly longer dialysis duration than No- or New-NRC (6.7±3.9 and 3.3±3.2 vs. 2.7±3.1 and 2.6±2.4 years, respectively), with NRC representing a relative risk of 1.72-fold [95% CI 1.6 – 1.8] for RCC development.
This study demonstrates an incidence of RCC in RTX which is more than ten-fold greater than that in the general population, and a strong association of RCC with NRC. The occurrence of NRC i.e., even a single cyst, confers a 1.7-fold higher risk of developing RCC in RTX. Furthermore, NRC development is not arrested post-transplant. The increased risk of RCC in the subgroups with a longer duration of uremia suggests the initial stimulus for NRC development stemming from a period of uremia was not arrested following transplantation. With potent immunosuppression added post-transplant, the risk for hyperplastic renal tubular cells to undergo malignant transformation increases, potentially triggering NRC to develop into RCC, especially in those with pre-existing NRC. Since early treatment of RCC gives excellent outcomes, regular ultrasonography performed within a month of transplantation, then every 5 years for those without cysts and every 2 years for those with cysts for early detection of RCC is recommended.
A. Goh1 and A. Vathsala1 as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
1Department of Renal Medicine, Singapore General Hospital
Corresponding author contact information:
Department of Renal Medicine, Block 6 Level 6, Singapore General Hospital
Outram Road Singapore 169608