Is a Limited Lymph Node Dissection An Adequate Staging Procedure for Prostate Cancer?:

Impact of Lymph Node Burden on Survival of High-risk Prostate Cancer Patients Following Radical Prostatectomy and Pelvic Lymph Node Dissection

AIM

To determine the impact of the extent of lymph node invasion (LNI) on long-term oncological outcomes after radical prostatectomy (RP).

MATERIAL AND METHODS

In this retrospective study, we examined the data of 1,249 high-risk, non-metastatic PCa patients treated with RP and pelvic lymph node dissection (PLND) between 1989 and 2011 at eight different tertiary institutions. We fitted univariate and multivariate Cox models to assess independent predictors of cancer-specific survival (CSS) and overall survival (OS). The number of positive lymph node (LN) was dichotomized according to the most informative cutoff predicting CSS. Kaplan-Meier curves assessed CSS and OS rates. Only patients with at least 10 LNs removed at PLND were included. This cutoff was chosen as a surrogate for a well performed PNLD.

RESULTS

Mean age was 65 years (median: 66, IQR 60-70). Positive surgical margins were present in 53.7% (n = 671). Final Gleason score (GS) was 2-6 in 12.7% (n = 158), 7 in 52% (n = 649), and 8-10 in 35.4% (n = 442). The median number of LNs removed during PLND was 15 (IQR 12-17). Of all patients, 1,128 (90.3%) had 0-3 positive LNs, while 126 (9.7%) had ≥4 positive LNs. Patients with 0-3 positive LNs had significantly better CSS outcome at 10-year follow-up compared to patients with ≥4 positive LNs (87 vs. 50%; p < 0.0001). Similar results were obtained for OS, with a 72 vs. 37% (p < 0.0001) survival at 10 years for patients with 0-3 vs. ≥4 positive LNs, respectively. At multivariate analysis, final GS of 8-10, salvage ADT therapy, and ≥4 (vs. <4) positive LNs were predictors of worse CSS and OS. Pathological stage pT4 was an additional predictor of worse CSS.

CONCLUSION

Four or more positive LNs, pathological stage pT4, and final GS of 8-10 represent independent predictors for worse CSS in patients with high-risk PCa. Primary tumor biology remains a strong driver of tumor progression and patients having ≥4 positive LNs could be considered an enriched patient group in which novel treatment strategies should be studied.

Pelvic lymph node dissection in prostate cancer: indications, extent and tailored approaches

PURPOSE

The purpose of this study is to review the current literature concerning the indication of pelvic lymph node dissection (PLND), its extent and complications in prostate cancer (PCa) staging, the available tools, and the future perspectives to assess the risk of lymph node invasion (LNI).

METHODS

A literature review was performed using the Medline, Embase, and Web of Science databases. The search strategy included the terms pelvic lymph nodes, PLND, radical prostatectomy, prostate cancer, lymph node invasion, biochemical recurrence, staging, sentinel lymph node dissection, imaging, and molecular markers.

RESULTS

PLND currently represents the gold standard for nodal staging in PCa patients. Available imaging techniques are characterized by poor accuracy in the prediction of LNI before surgery. On the contrary, an extended PLND (ePLND) would result into proper staging in the majority of the cases. Several models based on preoperative disease characteristics are available to assess the risk of LNI. Although ePLND is not associated with a substantial risk of severe complications, up to 10% of the men undergoing this procedure experience lymphoceles. Concerns over potential morbidity of ePLND led many authors to investigate the role of sentinel lymph node dissection in order to prevent unnecessary ePLND. Finally, the incorporation of novel biomarkers in currently available tools would improve our ability to identify men who should receive an ePLND.

CONCLUSIONS

Nowadays, the most informative tools predicting LNI in PCa patients consist in preoperative clinical nomograms. Sentinel lymph node dissection still remains experimental and novel biomarkers are needed to identify patients at a higher risk of LNI.

Differences in the rate of lymph node invasion in men with clinically localized prostate cancer might be related to the continent of origin

OBJECTIVE

To test whether the rate of lymph node invasion (LNI) differs between patients treated with radical prostatectomy (RP) at a European or a North American centre.

PATIENTS AND METHODS

In all, 1385 men had RP with bilateral lymphadenectomy for clinically localized prostate cancer (587 from Dallas, Texas and 798 from Milan, Italy). Univariate and multivariate analyses focused on the association between the continent of origin and the rate of LNI, after controlling for prostate-specific antigen (PSA) level, clinical stage, biopsy Gleason sum and the number of examined and removed lymph nodes.

RESULTS

European men had higher PSA levels (9.1 vs 7.8 ng/mL), a higher proportion of palpable cancers (44.5 vs 32.8%), more nodes removed (mean 14.9 vs 7.8) and a higher rate of LNI (9.0% vs 1.2%; all differences P < 0.001). In multivariate analyses that controlled for PSA level and clinical variables, European men had an 8.9-fold higher risk of LNI (P < 0.001) than their counterparts from the USA. Among preoperative variables, the continent of origin was the third most informative predictor of LNI (67.5%), after biopsy Gleason sum (74.3%) and the number of examined lymph nodes (71.0%), and improved the ability to predict LNI by 4.7%.

CONCLUSION

Men treated at a European centre had a 7.3-8.9-fold higher rate of LNI, despite adjusting for all clinical and pathological variables. It remains to be shown what predisposes European men to a higher rate of LNI.

Reliability of preoperative diagnostics and location of lymph node metastases in presumed unilateral prostate cancer

OBJECTIVE

To investigate the reliability of preoperative diagnostics in predicting the true histopathological stage and grade of prostate cancer, and to examine whether lymph node (LN) metastases in unilateral prostate cancer are located unilaterally and therefore whether it is justified to dissect only the ipsilateral LNs in presumed unilateral disease.

PATIENTS AND METHODS

LN metastases in clinically localized prostate cancer are often located near the internal iliac vessels. They will be detected by extended or sentinel pelvic LN dissection (PLND). Both techniques might be time-consuming and require extensive surgical experience. In all, 564 men with impalpable or unilateral palpable prostate cancer and positive biopsy cores only in one prostate lobe had a radical prostatectomy (RP) combined with radio-guided PLND and in some cases an extended PLND.

RESULTS

A median of six sentinel LNs (mean, seven) and six non-sentinel LNs (mean, seven) were dissected per patient; 52 of 564 men (9.2%) had positive LNs. Most men with unilateral disease had LN metastases on the same side of the pelvis. Comparing the clinical stage and grade with the tumour stage and grade of the RP specimen, there was a high percentage of upstaging and upgrading even in men with only one positive biopsy core.

CONCLUSION

Unilateral prostate cancer preferentially metastasizes to the ipsilateral pelvic LNs. Because there are a few cases of bilateral LN metastases even in unilateral disease, and as it is not possible to reliably predict unilateral disease on the basis of biopsy features, PLND only on the tumour-bearing side has a high risk of understaging, and would possibly leave LN metastases behind.

Validation of a nomogram predicting the probability of lymph node invasion based on the extent of pelvic lymphadenectomy in patients with clinically localized prostate cancer

OBJECTIVE

To develop a multivariate nomogram to predict the rate of lymph node invasion (LNI) in patients with clinically localized prostate cancer according to the extent of extended pelvic lymphadenectomy (PLND), which is associated with significantly higher rate of LNI.

PATIENTS AND METHODS

The study comprised 781 consecutive patients (median age 66.6 years, range 45-85) treated with PLND and radical retropubic prostatectomy (RRP) for clinically localized prostate cancer. Their median (range) prostate-specific antigen (PSA) level was 7 (1.03-49.91) ng/mL, and their clinical stages were T1c in 433 (55.4%), T2 in 328 (42%) and T3 in 20 (2.6%). Biopsy Gleason sums were <or= 6 in 514 (65.8%), 7 in 204 (26.1%) and 8-10 in 63 (8.1%). Multivariate logistic regression models were used to test the association between predictors including PSA level, biopsy Gleason sum, clinical stage, number of nodes removed and the rate of LNI. Finally, regression coefficients were used to develop a nomogram, which was internally validated with 200 bootstrap re-samples.

RESULTS

The median (range) number of lymph nodes removed was 14 (2-40); LNI was detected in 71 patients (9.1%). The univariate predictive accuracy for total PSA level, clinical stage, biopsy Gleason sum and number of total nodes removed and examined was 64.2%, 59.8%, 74% and 62.9%, respectively. Except for PSA (P = 0.2), all variables were statistically significant multivariate predictors of LNI at RRP (P <or= 0.001). A nomogram based on clinical stage, PSA level, biopsy Gleason sum and the number of total lymph nodes removed was 78.6% accurate, and 1.8% more accurate than a nomogram without the number of removed lymph nodes.

CONCLUSIONS

The extent of PLND is directly related to the probability of LNI. The risk of LNI increases linearly, and is proportional to the number of nodes removed and examined. The effect of the increased probability of LNI is weighted more heavily in men with more advanced clinical stage and grade.

Incidence of positive pelvic lymph nodes in patients with prostate cancer, a prostate-specific antigen (PSA) level of < or =10 ng/mL and biopsy Gleason score of < or =6, and their influence on PSA progression-free survival after radical prostatectomy

OBJECTIVE

To investigate how many men with low-risk prostate cancer had positive lymph nodes detected by radio-guided surgery and whether they had a higher biochemical relapse rate after radical prostatectomy, because in such patients most urologists dispense with operative lymph node staging, as nomograms indicate only a low percentage of lymph node metastases.

PATIENTS AND METHODS

The study included 474 men with a prostate-specific antigen (PSA) level of < or = 10 ng/mL, biopsy Gleason score of < or = 6 and positive biopsies in one (group 1, 315 men) or both lobes (group 2, 159 men); follow-up data were available in 357 men. Men with adjuvant radiation or hormone therapy before the occurrence of biochemical relapse were excluded.

RESULTS

Positive lymph nodes were detected in 17 men in group 1, and in 18 in group 2. In more than half of the patients (19/35) these nodes were found outside the region of standard lymphadenectomy. Men with node-positive disease had a higher biochemical relapse rate (P < 0.001). When the tumour was organ-confined and well differentiated in node-positive disease (Gleason score < or = 6) the biochemical relapse rate was lower than in men with higher tumour stage and grade.

CONCLUSIONS

When dissecting pelvic lymph nodes, extended or sentinel lymphadenectomy should be preferred. Removing the diseased nodes could improve the PSA progression-free survival, especially in well differentiated organ-confined disease.

Is a limited lymphadenectomy targeting obturator nodes alone an adequate procedure for Japanese men undergoing radical prostatectomy?

BACKGROUND

The objective of the present study was to investigate the significance of pelvic lymphadenectomy during radical prostatectomy in Japanese men with prostate cancer.

METHODS

A total of 178 consecutive patients who underwent radical prostatectomy and standard pelvic lymphadenectomy targeting the external iliac nodes and obturator fossa for clinically localized prostate cancer were studied. The median observation period of this series was 18 months (range: 3-36 months).

RESULTS

Lymph node metastases were detected in 13 patients; that is, positive nodes were located in the external iliac nodes alone in seven patients, the obturator fossa alone in four patients, and both external iliac nodes and obturator fossa in two patients. Of these 13 patients, all of the seven with more than one positive node demonstrated biochemical recurrence, whereas five of the six with single node involvement remained without signs of biochemical recurrence. Furthermore, a single positive node was located in the external iliac region in five of the six patients. When a group at high-risk for lymph node metastasis was defined as those meeting more than two of the following three criteria: (i) pretreatment serum prostate specific antigen value > or = 20 ng/mL; (ii) biopsy Gleason sum > or = 8; or (iii) percentage of positive biopsy core > or = 50%, the incidence of lymph node metastasis was 24.5% in the high-risk group and 0.8% in the low-risk group.

CONCLUSIONS

These findings suggest that limited dissection of the obturator node alone may not be sufficient for Japanese men undergoing radical prostatectomy; therefore, we recommend performing standard pelvic lymphadenectomy targeting both the external iliac nodes and the obturator fossa for patients at high-risk of lymph node involvement.