EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Objectives: Because of the risk of tumor implantation, a kidney with a small renal mass is not accepted as a donor in the kidney transplant program. Here, we evaluated the long-term outcomes of transplantation of kidneys with small renal mass.
Materials and Methods: We reviewed 14 donors who had been incidentally diagnosed with a small renal mass during standard donor evaluation. All donors underwent laparoscopic donor nephrectomy followed by bench resection of the mass. The negative margins were confirmed on the frozen section.
Results: On histopathological examination, 6 masses were reported as renal cell carcinoma, 4 were angiomyolipomas, 2 were oncocytoma, and 2 were papillary adenoma. After a median follow-up of 30 months, no recurrences were shown in the recipients. All recipients showed stable graft function.
Conclusions: When no other donor is available, a kidney with a small renal mass can be considered for living related kidney transplant. Bench excision of the mass was oncologically safe, with recipients having good long-term outcomes.

Key words : Bench partial nephrectomy, Donor shortage, Kidney transplantation, Tumor in donor kidney

The worldwide increase in the prevalence of end-stage renal disease and the shortage of available donors have made it necessary to increase the pool of potential graft donors. On routine evaluation of kidney donors, a small renal mass (SRM) is occasionally inci-dentally detected. Although the treatment options for SRM are debatable, surgical resection offers a cure. Various options are available, depending on the size and location of the tumor, patient preferences, and comorbidities of the patient.¹ As per oncological outcomes, a partial nephrectomy with free margins be-fore transplant could offer a cure for the donor without any risks to the recipient. In this study, we evaluated the long-term oncological and functional outcomes in recipients and donors in a series of living donor kidney transplants after ex vivo partial nephrectomy.

Materials and Methods

We retrospectively reviewed the prospectively maintained electronic records of all living donor nephrectomies from 2007 through 2023. We retros-pectively evaluated 14 healthy kidney donors who had been incidentally diagnosed with SRM during standard donor evaluation. All donors were living related donors as per institute protocols and The Transplantation of Human Organs and Tissue Act India (1994). All donors at our center were first- or second-degree relatives or spouses to the recipient. We included male or female donors who were more than aged 18 years and less than 70 years.
All donors with SRM underwent metastatic evaluation before graft procurement. After laparos-copic donor nephrectomy, on-bench partial nephrectomy/resection was performed, and frozen-section histopathological examination was done to confirm the negative surgical margins before transplant of allograft (Figure 1, Figure 2, and Figure 3).
Recipients and donors were followed for functional kidney transplant profiles as per our institutional protocol. For oncological outcomes, recipients and donors were followed up with ultrasonography and/or magnetic resonance imaging every 6 months. Donors and recipients provided detailed informed consent. All cases were discussed among our multi-disciplinary team before transplant.

Of 2360 voluntary living kidney donors, 14 were identified with incidental SRM during routine donor evaluation. Mean age of donors was 41.85 ± 7.62 years with a 4:3 male-to-female ratio. Of the 14 cases, 6 had clear cell renal carcinoma; the remaining cases showed benign tumors on histopathological examination (Table 1). Mean age of recipients was 43.00 ± 5.50 years. No substantial postoperative complications were shown in recipients except for 1 patient who developed features of mild acute tubular necrosis, which resolved with conservative management. After a median follow-up of 30 months, no recurrences were shown in tumors in donors and recipients. Patients showed no long-term complications in the transplanted kidneys and showed stable graft function. The cancer-specific survival was 100%. Through last follow-up, both recipients and donors showed good outcomes.

In general, renal grafts from older voluntary donors, grafts with complex anatomical variants, grafts from donors with untreated metabolic diseases, and grafts from donors with potentially transmissible diseases such as infections or malignancies are not considered because of the suboptimal and variable outcomes in recipients.²
In the living donor transplant program, the donor is always the utmost priority. Hence, donor screening should include both kidney function analysis and assessment of clinical situations or diseases that may increase disease transmission to the recipient (eg, neoplasia, infections).³
Incidence of kidney cancer, especially asympto-matic and SRM, has steadily increased over recent decades.⁴ Among the renal masses, renal cell carcinoma is the most common solid lesion in the kidney and accounts for approximately 90% of all kidney malignancies. Some risk factors consistent with increased risk for renal cell carcinoma include male sex, donor age (older than aged 60 years), obesity, and history of smoking and hypertension.⁵ The incidental finding of a SRM during donor workup or a previous history of renal tumor in either recipients or donors is still a debatable topic. The use of immunosuppressive drugs leads to about 5- to 10-time increased risk of renal cell carcinoma among transplant patients compared with the general population.⁶
Despite the associated potential complications, like perioperative bleeding, urine leak, and recurrence, agreement remains that partial nephrectomy is curative for most T1aN0M0 lesions, is the accepted treatment of choice in otherwise healthy individuals, and carries a small risk of recurrence and metastasis. Other surgical alternatives are radiofrequency ablation, microwave ablation, or cryoablation, which are usually used in patients with small cortical tumors with high surgical risk.^7,8
Studies have supported the evidence of use of donor kidneys with SRM. Kidney transplant in donors with small renal masses after ex vivo excision of small tumors has been reported since 1982.⁹ Previously, ex vivo excision of tumor from deceased kidney donors was mainly reported; however, living donor nephrectomy with SRM is presently also considered.
Cristea and colleagues recently reviewed 147 patients who underwent tumor excision before kidney donation, including 120 who were living kidney donors and 27 who were deceased kidney donors. The investigators concluded that use of kidneys from donors with SRMs is feasible and safe, with an overall recurrence rate of less than 1.5%.¹⁰
In our study, we noted 14 cases of incidentally detected SRMs between 2007 to 2021 on routine donor evaluation. On histopathological examination, 6 cases were reported as clear cell renal cell carcinoma, 4 were angiomyolipoma, 2 were oncocytoma, and 2 were papillary adenoma. Donors had preoperative 3-phase computed tomography renal angiography as a stan-dard protocol to define renal anatomy, vasculature, and associated characteristics, like stones or mass lesions. Standard laparoscopic donor nephrectomy was performed, and, on bench, further dissection along with partial nephrectomy was performed. Intraoperative blood loss, duration of surgery, and total hospital stay were comparable to routine laparoscopic donor nephrectomy cases. Warm ischemia time was similar, but cold ischemia time was slightly raised compared with other donor nephrectomies. Donor creatinine levels in the postoperative period at 1 and 6 months were within the normal range. No disease recurrence was found in donors on follow-up. Graft function in recipients was stable and comparable to recipients from donors with normal kidney without any SRM.
In a systematic review from Hevia and colleagues, 5-year overall survival rate was 92% and graft survival rate was 95.6% in recipients of kidneys with small renal tumors excised ex vivo.¹¹ Mean recipient age was 44.2 years, and kidneys used were retrieved from living donors in 86% (94/109) of cases. The authors suggested that, although the number of cases was low, kidneys with excised SRMs are an acceptable graft source without compromising oncological outcomes and with similar functional outcomes to other donor kidneys.¹¹ Use of such kidneys should be mainly reserved for patients aged >60 years with a substantial survival advantage by maximizing their residual renal function.¹² In another study from Piana and colleagues, use of grafts with SRM may be considered a safe option after bench table tumor excision in both living and deceased donors.¹³
We suggest that optimal use of kidneys with SRM should include careful selection; their use will serve a reasonable benefit to the society by helping both donors and recipients. Initial approval from ethical/legal committees and proper consent and counseling before surgery are necessary regarding risk of cancer recurrence and transmission and risk of surgical complications related to the tumor excision.

If no other appropriate donor is available, kidneys with SRMs can be considered for kidney transplant. Bench excision of SRM in donor nephrectomy is a viable and safe surgery and can increase the pool of living kidney donors with good outcomes. The most important advantage is that donors will have the removal of any kidney tumor and the recipient will receive a tumor-free kidney at the same time.

Volume: 23 Issue: 2 February 2025

FULL TEXT