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Extended Pelvic Lymph Node Dissection for Prostate Cancer: Do More Nodes Mean Better Survival?

Extended Pelvic Lymph Node Dissection for Prostate Cancer: Do More Nodes Mean Better Survival?

A longstanding debate in the prostate cancer surgery literature surrounds the optimal extent of the pelvic lymph node dissection (PLND). An extended PLND (ePLND) reaches from the bifurcation of the common iliac artery superiorly to the femoral canal inferiorly; posteriorly, the obturator nerve, obturator vessels, and internal iliac artery are skeletonized. A standard PLND differs in that the internal iliac artery nodes are not removed. While ePLND is popular in Europe, standard PLND has always been preferred in the United States, where rates of advanced disease are significantly lower. These approaches carry with them differing morbidities as well as the possibility of varied staging and curative advantages.

Patients who underwent radical retropubic prostatectomy for prostate cancer prior to the prostate-specific antigen (PSA) era in the United States had, as a group, significant lymph node positivity, with rates ranging from 20% to 40%. Since the establishment of PSA screening and the resultant stage migration, this rate has dropped to near 1%.[1] The falling incidence of lymph node metastasis suggests that patients in the modern era are much less likely to benefit from PLND than those treated in the past, especially when an extended dissection is considered.

A well-demonstrated problem with ePLND is the morbidity associated with the additional dissection, although the literature appears to be mixed on this subject. Studies have quoted a complication rate for PLND that ranges from 4% to 53%; a recent study noted a 14% complication rate with standard PLND compared with a 35% rate in patients who underwent an extended procedure.[2] Additionally, in a 2003 trial, 123 patients underwent unilateral ePLND with standard PLND on the contralateral side; the side chosen for ePLND was randomly assigned. This study reported an overall complication rate of 10.6%, although 75% of the complications were on the side on which the extended procedure was performed.[3] It appears that most complications associated with PLND are minor, and most often lymphatic-related (eg, lymphocele, lymphedema), but they occur more frequently with the extended procedure.

Additionally, many surgeons cite an increased staging ability with ePLND, although studies have shown that the number of lymph nodes removed at the time of surgery does not affect the disease progression or cancer-specific survival in patients found to have no nodal disease.[4] Because node-negative patients who undergo a more limited PLND are unlikely to be understaged in a clinically significant manner, it does not appear to be necessary to perform extended node dissections in all patients simply for staging purposes.

Proponents of the ePLND in the modern era maintain that there is improved therapeutic benefit to identification and removal of additional (and possibly micrometastatic) diseased lymph nodes. One group reported that patients who underwent ePLND trended toward improved biochemical recurrence–free survival compared with those undergoing standard PLND; the improvement in survival was only significant in those patients with fewer than 15% positive nodes on ePLND.[5] Studies showing such a benefit are retrospective reviews that cannot overcome the Will Rogers effect, in which stage migration induces a perceived change in outcomes.[6] Applying this concept to our prostate cancer discussion, some patients with low-volume positive lymphadenopathy found on ePLND would have been considered low-risk patients after standard PLND. These patients will have improved outcomes compared with typical node-positive patients, improving the overall outcomes of patients undergoing ePLND. It is, in fact, exactly these patients with low-volume lymph node disease who have improved survival with extended lymph node dissection, based on such retrospective studies. A telling clue from the study previously noted was the lack of improvement in prostate cancer–specific survival in those same patients after ePLND.[5]

We may never know the answer to the question of whether extent of PLND affects prostate cancer survival. In spite of the concern of critics, in the United States the continued decline in metastatic lymphadenopathy at the time of surgery has prompted some surgeons to forgo the PLND altogether.[6] In the absence of more compelling data, such an approach is reasonable, so long as the patient undergoes a process of informed consent. Retrospective studies are simply unable to overcome the problems associated with increased detection of subclinical disease afforded by ePLND; thus, a prospective randomized trial is required to definitively answer this question. At the present time, without clear data to suggest improved survival for patients undergoing ePLND, the procedure cannot be universally recommended.

The views expressed in this article are those of the authors and do not necessarily represent the views of the Department of Veterans Affairs.

Financial Disclosure: The authors have no significant financial interest in or other relationship with the manufacturer of any product or provider of any service mentioned in this article.

References

1. Eifler JB, Feng Z, Lin BM, et al. An updated prostate cancer staging nomogram (Partin tables) based on cases from 2006 to 2011. BJU Int. 2013;111:22-9.

2. Rousseau B, Doucet L, Perrouin Verbe MA, et al. [Comparison of the morbidity between limited and extended pelvic lymphadenectomy during laparoscopic radical prostatectomy]. Prog Urol. 2014;24:114-20.

3. Clark T, Parekh DJ, Cookson MS, et al. Randomized prospective evaluation of extended versus limited lymph node dissection in patients with clinically localized prostate cancer. J Urol. 2003;169:145-7; discussion 47-8.

4. DiMarco DS, Zincke H, Sebo TJ, et al. The extent of lymphadenectomy for pTXNO prostate cancer does not affect prostate cancer outcome in the prostate specific antigen era. J Urol. 2005;173:1121-5.

5. Bivalacqua TJ, Pierorazio PM, Gorin MA, et al. Anatomic extent of pelvic lymph node dissection: impact on long-term cancer-specific outcomes in men with positive lymph nodes at time of radical prostatectomy. Urology. 2013;82:653-8.

6. Allaf ME, Partin AW Carter HB. The importance of pelvic lymph node dissection in men with clinically localized prostate cancer. Rev Urol. 2006;8:112-9.

 
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