To the Editor:
The recent paper by Nalesnik impressed us owing to its aim to promote organ transplantation while minimizing the risk of cancer transmission (1).
In Japan, 11 985 dialysis patients are on waiting lists for kidney transplantation, and the mean waiting time is 15 years. This desperate shortage of organs has given rise to the sales and trafficking of organs as well as transplant tourism.
In an effort to find a means to expand the pool of donors, Mannami et al. have reported retrospectively 42 cases of the transplantation of “restored” kidneys. Eight of the kidneys were obtained after nephrectomy for renal cell carcinoma (RCC) that was 1.2–3.5 cm in size, and in these cases no tumor recurred during a follow-up period that ranged from 12 to 135 months. (2) In addition, Nicol reported 43 cases of the transplantation of restored kidneys after nephrectomy for renal tumors (<3 cm) (3). More than 80% of small renal tumors (<4 cm) are treated by nephrectomy in Japan; hence, an estimated 2000 kidneys are discarded each year. However, “diseased kidney transplantation” was prohibited by the Japanese government in 2007, with the exception of clinical trials.
A kidney that has been restored after resection of a small RCC might be of benefit to selected recipients who anticipate a long-waiting period, or to elderly persons (2–4). Partial nephrectomy for T2 or more advanced RCC seems to achieve a similar oncological outcome to radical nephrectomy (5). This is a little risky for kidney transplantation, but partial nephrectomy for T1a tumors (<4 cm) might be acceptable because of the lower risk of cancer transmission.
We performed a prospective clinical trial (ClinicalTrials.gov NCT00980317) in which five discarded kidneys were restored and transplanted into five unrelated recipients. The donors were selected from among patients who had small RCC (2.0–3.8 cm), and who opted to undergo nephrectomy after extensive discussion of other treatment modalities. Five male patients aged 51–79 years donated the kidneys. The tumors included one granular cell RCC and four clear cell subtypes. Each restored kidney was transplanted into an unrelated recipient, who was selected from among 56 candidate recipients by a third-party selection committee. Four recipients have experienced rejection episodes so far, and the latest serum creatinine levels, after a follow-up period of 11–17 months, range from 1.22 to 1.67 mg/dL. There has been no tumor recurrence. We reported these preliminary results at the 2011 annual meeting of the AUA, and concluded that patients selected tolerate restored kidney transplantation, and achieve good renal function without tumor recurrence. In addition to these five cases, we have reviewed the eight cases reported by Mannami and analyzed another three cases that have been followed up for 2–6 months in the second stage of the on-going clinical trial, and our conclusion remains the same.
Further large-scale clinical trials using kidneys from patients with RCC of various histological types and stages are warranted to evaluate the true risk of cancer transmission and the operative morbidity associated with the transplantation of restored kidneys.