活體捐贈腎臟伴有小腫塊仍然適合移植

作者：Laurie Barclay, MD  
出處：WebMD醫學新聞

　　December 29, 2009 — 根據12月英國國際泌尿學期刊(British Journal of Urology International)的系列案例報告結果，活體捐贈腎臟伴有小腫塊仍然適合移植給高風險的接受者。
　　
　　雖然使用這種腎臟有爭議且風險高，但是因為遺體器捐者的器官短缺、以及等待移植時的存活率低，研究者決定進行嘗試。5對捐贈者和接受者在確認捐贈者腎臟有小腫塊之後，予以告知並獲得同意。
　　
　　共同作者、馬里蘭大學醫學院泌尿科、泌尿腹腔鏡手術與微創手術主任、外科助理教授Michael W. Phelan醫師向Medscape Transplantation表示，此技術當然不是解決器官短缺的最佳方案。
　　
　　不過，隨著X光照相技術有所改善，越來越多小腫塊被發現，如果所有伴有小腫塊的病患都被排除於捐贈者之外，適合的捐贈者只會越來越少。
　　
　　此系列案例分析的目標是，評估在活體捐腎者的例行檢查中偶然發現有腎臟腫塊的高風險腎臟，移植到生命有限之血液透析病患的結果。
　　
　　【必須是小且僅限於該器官的腫塊】
　　Phelan醫師表示，適合的捐贈者其腎臟腫塊必須小且僅限於該器官，此外，我們這一系列案例的所有接受者均為重症患者，也就是長期血液透析存活不佳者。
　　
　　在評估捐贈者時，Phelan醫師的團隊確認5個小的(<2.3公分)偶發腎腫塊，和這5對捐贈者與接受者詳細討論可能的風險之後獲得知情同意，所有病患都進行標準轉移評估。以腹腔鏡摘取捐贈者腎臟之後，研究者在後桌(back table)進行部份腎切除，並使用冷凍切片分析，以確認診斷和確保手術邊緣為陰性，之後進行移植。
　　
　　5對捐贈者與接受者中，有2對無親戚關係，3對有基因關係。接受者年紀範圍為47-61歲(平均年紀54歲)，捐贈者年紀為38-72歲(平均年紀38歲)。除了末期腎臟病之外，所有病患都有嚴重高血壓、心血管疾病以及其他重要共病症。
　　
　　Phelan醫師解釋，此手術所考量的主要風險是將癌症從捐贈者轉移到接受者，藉由充分的檢查，此風險低，但是仍然有風險存在，必須在和捐贈者與接受者的討論中告知並獲得同意。術前，捐贈者一定要進行轉移檢查。
　　
　　這系列案例發現的5個腫塊直徑範圍從1.0 -2.3公分，3個是腎細胞癌，2個是良性血管肌肉脂肪瘤，腎細胞癌中，1個是囊狀，1個是透亮細胞(clear cell)，1個是乳突樣，分別是Fuhrman分級第2、2、3級。移植的腎臟顯示沒有長期併發症徵兆。
　　
　　移植之後，1個病患發生延遲急性體液排斥，給予適當治療。捐贈者和接受者都進行定期的影像檢查。追蹤期間中位數為15個月(範圍為1-41個月)。
　　
　　最後追蹤時，4個病患存活，1個死於跌倒引起的併發症。癌症特定存活率為100%，在最後追蹤時，沒有病患有任何的復發跡象。根據這些發現，有小腫塊的活體捐贈腎臟經仔細的後桌部份腎切除之後，可以接受使用於高風險接受者。
　　
　　Phelan醫師結論表示，我們的系列研究和Nicol醫師與其他引述文獻，認為小的、侷限於該器官的腎癌，在完整切除腫瘤之後可以安全地用於移植。此外，小於2公分的腫瘤約40% -50%為良性，即使電腦斷層懷疑它們是癌症，當然，這些良性腫瘤如血管肌肉脂肪瘤，可以無疑的用於移植。
　　
　　【困難的兩難】
　　澳洲Woolloongabba雅麗珊公主醫院、昆士蘭大學南部臨床學院腎臟移植小組的David Nicol醫師在編輯評論中表示，許多移植中心有關是否使用有小腫塊的活體腎臟進行移植的決定將會增加。
　　
　　Nicol醫師寫道，捐贈者、可能的接受者、參與照護的醫師，都將面對一個困難的兩難，首先，捐贈者表明意願或自願進行腎切除，根據X光檢查結果，其相關風險與對可能之接受者的利益，都需再度評估他們的立場與決定。
　　
　　意外發現腎腫塊病患的治療選項包括腎元細胞保留手術、微創燒灼手術、腎切除術，某些特定案例則可以先觀察。相較於腎臟切除術，一般會偏好腎元細胞保留手術，因為它有相同的癌症特定存活且保留腎功能，其他手術風險包括出血、尿水外溢、傷口相關併發症。
　　
　　Nicol醫師寫道，相較於其他病患，可能的活體捐贈者解決了腎切除術的問題與風險，也提供幫助給可能的接受者。
　　
　　他指出，許多案例中，如果這可以提供進行透析的接受者有更好的結果、如果有適當的考慮遺體器捐，更多的資訊並不會改變他們接受腎臟切除術的動機，接受者須面對可能會有癌症診斷的挑戰，以及局部復發和轉移疾病風險之後遺症。
　　
　　不過，這些風險和那些持續透析的風險相抵銷，遺體器官移植的後續可能性則未知。
　　
　　Nicol醫師結論表示，整體而言，腎元細胞保留手術後的腫瘤復發風險明顯小於持續透析之風險，特別是年長者或無法接受透析者。
　　
　　他寫道，醫師面對捐贈者和接受者時，需體認到這兩者的兩難，需提供整體的風險觀、支持並尊重病患自主，協助做出最後決定。年紀和個別情況會影響提供的建議。
　　
　　研究作者與Nicol醫師皆宣告沒有相關財務關係。


Live Donor Kidneys With Incidental Small Masses May Be Suitable for Transplantation

By Laurie Barclay, MD
Medscape Medical News

December 29, 2009 — Live donor kidneys with incidental small masses may still be suitable for transplantation to high-risk recipients, according to the results of a case series reported in the December issue of the British Journal of Urology International.

Although using this source of kidneys has been considered controversial and high-risk, the investigators decided to try it because of the ongoing shortage of organs from deceased donors and because of low recipient survival while awaiting transplant. Five donors and recipients gave informed consent for surgery after small masses were identified in the donor kidneys.

"This technique is certainly not the magic solution for the organ shortage," coauthor Michael W. Phelan, assistant professor of surgery and director of urological laparoscopy and minimally invasive surgery, Division of Urology, University of Maryland School of Medicine in Baltimore, told Medscape Transplantation.

"However, radiographic technology is improving, and more and more small, incidental masses are being discovered. If all of these small, incidental mass patients are excluded from the donor pool, this could increase the shortage of approved donors."

The goal of this case series analysis was to evaluate transplantation of high-risk kidneys with incidental renal masses, which are occasionally found during the routine evaluation of a living kidney donor, into recipients with limited life expectancy on hemodialysis.

Masses Must Be Small, Organ-Confined

"The eligible donors must present with small, organ-confined renal masses," Dr. Phelan said. "Additionally, all of the recipients in our series were very ill and considered high risk; that is, poor survival on long-term hemodialysis."

During donor evaluation, Dr. Phelan's group identified 5 kidneys with small (<2.3 cm), incidental, enhancing renal masses. Detailed discussion of potential risks led to obtaining informed consent in all 5 donor-recipient pairs. Standard metastatic evaluation was performed in all patients. After laparoscopic donor nephrectomy, the investigators performed a back-table partial nephrectomy and used frozen section analysis to confirm the diagnosis and to ensure that surgical margins were negative before transplantation.

Two of the 5 donor pairs were unrelated, and 3 were genetically related. Age range was 47 to 61 years in the recipients (average age, 54 years) and 38 to 72 years in the donors (average age, 38 years). In addition to end-stage renal disease, all patients had severe hypertension, cardiovascular disease, or other significant comorbidity.

"The most concerning risk [of this procedure] is that of transmitting a cancer from donor to the recipient," Dr. Phelan said. "Given the extensive work-up, this risk is low, but certainly the risk exists and has to be included in the informed consent discussion with the donor-recipient pair. Preoperatively, metastatic work-up is essential in the donor."

Of the 5 identified masses in this series, which ranged from 1.0 to 2.3 cm in diameter, 3 were renal cell carcinomas and 2 were benign angiomyolipomas. Of the renal cell carcinomas, 1 was cystic, 1 was clear cell, and 1 was papillary; these were Fuhrman grades II, II, and III, respectively. The transplanted kidneys showed no signs of long-term complications.

After transplantation, 1 patient developed delayed acute humoral rejection, which was treated appropriately. Periodic imaging was performed both for donor and recipient. Median duration of follow-up was 15 months (range, 1 - 41 months).

At last follow-up, 4 patients were alive and 1 had died from complications after a fall. Cancer-specific survival was 100%, and none of the patients had any evidence of local recurrence at the last follow-up. These findings suggest that it may be acceptable to transplant live donor kidneys with incidental small renal masses into high-risk recipients after careful back-table partial nephrectomy.

"Our series, as well as that of Dr. Nicol and others cited, indicate that small, organ-confined kidney cancers can be transplanted safely if the tumor is excised completely," Dr. Phelan concluded. "Additionally, approximately 40% to 50% of tumors less than 2 cm are benign, even though they are suspicious for cancer on [computed tomography] scans. Certainly, these benign tumors — such as angiomyelolipomas — can be transplanted without question or concern."

A Difficult Dilemma

In an accompanying editorial, David Nicol, MD, from the Renal Transplant Unit and Southern Clinical School, University of Queensland, Princess Alexandra Hospital, in Woolloongabba, Brisbane, Australia, notes that the decision of whether to transplant live donor kidneys with small masses may arise at many transplant centers.

"The donor, their potential recipient, and clinicians involved with the care of both are then confronted with a difficult dilemma," Dr. Nicol writes. "First, the donor who has indicated a desire or willingness to undergo nephrectomy and its associated risk on an altruistic basis for the benefit of the potential recipient needs to reassess their position and decision, based on the radiological findings."

Treatment options for a patient with an incidentally detected renal mass may include nephron-sparing surgery, minimally invasive ablative procedures, nephrectomy, and observation in selected cases. Although nephron-sparing surgery is often preferred over nephrectomy because of its equivalent cancer-specific survival with preservation of overall renal function, additional surgical risks include bleeding, urinary leakage, and wound-related complications.

"By contrast with other patients, the potential live donor has resolved the issue of nephrectomy and its risks, for the benefit of their potential recipient," Dr. Nicol writes.

"In many cases the additional information might not alter their motivation to undergo nephrectomy if this would provide a better outcome for their recipient than remaining on dialysis, and if there was suitable consideration of a deceased donor transplant," he points out. "The recipient might find the diagnosis of a possible cancer challenging, as a consequence of the risks of local recurrence and metastatic disease."

However, these risks may be offset by those associated with continued dialysis and the possibility that subsequent deceased-donor transplantation may not be available.

"Overall, the risks of tumour recurrence after [nephron-sparing surgery] are substantially less than ongoing dialysis, particularly in the elderly or in the context of tenuous access to dialysis," Dr. Nicol concludes.

"Clinicians dealing with the donor and recipient need to recognise the dilemma confronting both individuals, and assist with the final decision by providing a balanced perspective of the risks, acting as advocates for both, as well as respecting their autonomy of choice," he writes. "The age and individual circumstances obviously will influence the advice provided."

The study authors and Dr. Nicol have disclosed no relevant financial relationships.

BJU Intl. 2009;104:1655-1660.