Correspondence University Hospital of Bern, Department of Urology, Inselspital, CH-3010 Bern, Switzerland

Email urs.studer@insel.ch

Original article

Touijer K et al. (2007) Standard versus limited pelvic lymph node dissection for prostate cancer in patients with a predicted probability of nodal metastasis greater than 1%. J Urol 178: 120–124   PubMed

Synopsis

Background

The stage migration of prostate cancer has led to a decrease in the extent of lymph node dissection in patients who are considered to be at low risk of lymph node metastases. This approach is questionable, however, because the definition of patients who are at high and low risk of metastasis is variable, metastatic lymph nodes might go undetected if limited dissection is performed, and evidence indicates that extended node dissection has a positive effect on disease-free survival.

Objectives

The objectives of this study were to compare the yield of positive lymph nodes after standard or limited pelvic lymph node dissection (PLND) in patients with prostate cancer and a risk of nodal metastasis >1%, and to determine the feasibility of laparoscopic PLND.

Design and intervention

The study included patients with clinically localized adenocarcinoma of the prostate who underwent radical prostatectomy and PLND between 1 January 2003 and 30 October 2005 at the Memorial Sloan–Kettering Cancer Center, New York, NY. Patients underwent either retropubic standard PLND, laparoscopic standard PLND, or laparoscopic limited PLND. Standard PLND included the external iliac, obturator and hypogastric lymph node groups, and limited PLND included the external iliac nodes only. Exclusion criteria were receipt of neoadjuvant hormonal therapy, and a risk of nodal metastasis <1% according to predictions using the Partin tables. Patients' preoperative parameters (biopsy Gleason score, PSA level and clinical stage) and pathologic parameters (pathological Gleason score and stage, extracapsular extension and seminal vesicle invasion) were determined.

Outcome measures

The outcome measures were the detection rate of positive lymph nodes, and the total number of lymph nodes retrieved.

Results

In total, 648 patients were included in the analysis; 367 patients underwent retropubic standard PLND, 104 patients underwent laparoscopic standard PLND, and 177 patients underwent laparoscopic limited PLND. The preoperative and pathologic features were similar for patients who underwent standard or limited PLND. The detection rate of positive lymph nodes was higher in patients who underwent standard PLND compared with limited PLND (11.4 versus 4.1%, P = 0.009), and the median number of lymph nodes retrieved was also higher in patients who underwent standard PLND than in patients who underwent limited PLND (12 versus 9 nodes, P < 0.001). On multivariate logistic regression analysis, the odds of node positivity were 7.15 and 8.31 times higher for patients who underwent standard PLND rather than limited PLND, when controlling for preoperative and pathological parameters, respectively. When the analysis was limited to patients who had received laparoscopic treatment, the median number of nodes retrieved was 14 and 9 nodes by standard PLND and limited PLND, respectively, and the node-positive rate was 15.4% and 4.1% in patients who underwent standard PLND and limited PLND, respectively.

Conclusions

Standard PLND yields higher positive and total node counts than limited PLND, and standard laparoscopic PLND is a feasible approach.

Commentary

The role of PLND in patients with prostate cancer is still under debate for various reasons. Firstly, the value of PLND is contestable. The incidence of prostate cancer in elderly men is several-fold higher than the mortality associated with the disease, even if patients are left untreated; therefore, prostatectomy and PLND will not necessarily translate into improved survival for many patients. In addition, contrary to prior belief, patients with early-stage prostate cancer can have systemic spread—indicated by serum PSA level relapse after radical removal of apparently organ-confined pT1/pT2a/pT2b disease—and, again, PLND might not change the final outcome for these patients. Furthermore, although the morbidity associated with PLND is low, it is never 0%.

Secondly, the template of lymphadenectomy that should be used in PLND is controversial. As shown in this paper by Touijer and colleagues, the yield of positive nodes is 4% if the nodes are removed only along the external iliac vessels, but this figure increases to 15.4% if nodes are also removed from the obturator fossa and along the internal iliac vessels. Indeed, performing a meticulous lymph node dissection along the medial and lateral borders of the internal iliac vessels seems to be of utmost importance. In our series, approximately two out of every three positive resected nodes were exclusively retrieved along the internal iliac vessels or combined with other regions.¹ While Touijer et al. convincingly confirmed that PLND of the external iliac, obturator and hypogastric lymph node groups significantly increases the yield of positive nodes, evidence indicates that the primary lymphatic landing sites of the prostate might even extend beyond this PLND template. On the basis of our recent mapping study, the template for PLND used by Touijer et al. would contain only approximately 60% of the possible primary lymphatic landing sites.²

In view of these points, PLND should be restricted to those patients at intermediate or high risk of having nodal metastases. In general, these patients have a serum PSA level >10 ng/ml (provided the PSA elevation is not caused by prostatitis) or a serum PSA level <10 ng/ml with a biopsy Gleason score of 7 or higher.³ PLND has gained therapeutic importance over the last decade, because we know from several series that the patients in whom metastatic lymph nodes have been removed can remain free of PSA relapse for many years.⁴ Furthermore, the Surveillance, Epidemiology, and End Results (SEER) program, encompassing 13,020 patients who have undergone radical prostatectomies, showed that "extensive lymphadenectomy reduces the long-term risk of prostate cancer-related death, even in patients with negative nodes compared with patients without lymphadenectomy".⁵ The Memorial Sloan–Kettering Cancer Center group also reported that resection of apparently negative nodes seems to benefit patients, and the more nodes that are removed the better.⁶ Indeed, some microscopic metastases are detectable only with immunohistochemistry or polymerase chain reaction techniques. These findings do not mean that every resected node has to be analyzed with these time-consuming and expensive techniques, but rather that performing a PLND, at least to the extent described by Touijer et al., is important in patients with prostate cancer who have an intermediate to high risk of lymph node metastasis.

Acknowledgments

The synopsis was written by Rachel Murphy, Associate Editor, Nature Clinical Practice.

References

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