Lymph node dissection during robot-assisted radical prostatectomy: where do we stand?

Overall rate, location, and predictive factors for positive surgical margins after robot-assisted laparoscopic radical prostatectomy for high-risk prostate cancer

We report the overall rate, locations and predictive factors of positive surgical margins (PSMs) in 271 patients with high-risk prostate cancer. Between April 2008 and October 2011, we prospectively collected data from patients classified as D'Amico high-risk who underwent robot-assisted laparoscopic radical prostatectomy. Overall rate and location of PSMs were reported. Stepwise logistic regression models were fitted to assess predictive factors of PSM. The overall rate of PSMs was 25.1% (68 of 271 patients). Of these PSM, 38.2% (26 of 68) were posterolateral (PL), 26.5% (18 of 68) multifocal, 16.2% (11 of 68) in the apex, 14.7% (10 of 68) in the bladder neck, and 4.4% (3/68) in other locations. The PSM rate of patients with pathological stage pT2 was 8.6% (12 of 140), 26.6% (17 of 64) of pT3a, 53.3% (32/60) of pT3b, and 100% (7 of 7) of pT4. In a logistic regression model including pre-, intra-, and post-operative parameters, body mass index (odds ratio [OR]: 1.09; 95% confidence interval [CI]: 1.01-1.19, P= 0.029), pathological stage (pT3b or higher vs pT2; OR: 5.14; 95% CI: 1.92-13.78; P = 0.001) and percentage of the tumor (OR: 46.71; 95% CI: 6.37-342.57; P< 0.001) were independent predictive factors for PSMs. The most common location of PSMs in patients at high-risk was the PL aspect, which reflects the reported tumor aggressiveness. The only significant predictive factors of PSMs were pathological outcomes, such as percentage of the tumor in the specimen and pathological stage.

A receptor-targeted fluorescent radiopharmaceutical for multireporter sentinel lymph node imaging

PURPOSE

To determine the imaging and receptor-binding properties of a multireporter probe designed for sentinel lymph node (SLN) mapping via nuclear and fluorescence detection.

MATERIALS AND METHODS

The animal experiments were approved by the institutional animal care and use committee. A multireporter probe was synthesized by covalently attaching cyanine 7 (Cy7), a near-infrared cyanine dye, to tilmanocept, a radiopharmaceutical that binds to a receptor specific to recticuloendothelial cells. In vitro binding assays of technetium 99m (99mTc)-labeled Cy7 tilmanocept were conducted at 4°C by using receptor-bearing macrophages. Optical SLN imaging after foot pad administration was performed by using two molar doses of Cy7 tilmanocept. Six mice were injected with 0.11 nmol of 99mTc-labeled Cy7 tilmanocept (low-dose group); an additional six mice were injected with 31 nmol of 99mTc-labeled Cy7 tilmanocept (high-dose group) to saturate the receptor sites within the SLN. After 2.5 hours of imaging, the mice were euthanized, and the sentinel and distal lymph nodes were excised and assayed for radioactivity for calculation of SLN percentage of injected dose and extraction. Four mice were used as controls for autofluorescence. Standard optical imaging software was used to plot integrated fluorescence intensity against time for calculation of the SLN uptake rate constant and scaled peak intensity. Significance was calculated by using the Student t test.

RESULTS

In vitro binding assays showed subnanomolar affinity (mean dissociation constant, 0.25 nmol/L±0.10 [standard deviation]). Fluorescence imaging showed a detection sensitivity of 1.6×10(3) counts·sec(-1)·μW(-1) per picomole of Cy7. All four imaging metrics (percentage of injected dose, SLN extraction, SLN uptake rate constant, and expected peak fluorescence intensity) exhibited higher values (P=.005 to P=.042) in the low-dose group than in the high-dose group; this finding was consistent with receptor-mediated image formation.

CONCLUSION

The multireporter probe 99mTc-labeled Cy7 tilmanocept exhibits in vitro and in vivo receptor-binding properties for successful receptor-targeted SLN mapping with nuclear and optical imaging.

Preoperative sentinel lymph node mapping of the prostate using PET/CT fusion imaging and Ga-68-labeled tilmanocept in an animal model

Sentinel lymph node (SLN) identification with preoperative image guidance may improve pathological staging of prostate cancer by identifying nodes outside the standard template of dissection. Four anesthetized male dogs received an intra-prostatic injection of Ga-68-labeled tilmanocept. Every 20 min the pelvic lymph nodes were imaged using PET/CT fusion imaging. At 90 min post-injection a prostatectomy and extended lymphadenectomy were completed; ex vivo radioactivity was recorded for each node using a handheld gamma detector, and confirmed by calculation of percent-of-injected dose (%ID) via assay of Ga-68 radioactivity. SLNs were defined as containing >10 % of the maximum %ID. Preoperative PET/CT fusion imaging identified a mean of 4.25 lymph nodes per animal (range 3-7); the mean number of SLN per animal was 4.00 (range 2-6).Of the excised SLNs, 29 % were located in the standard external iliac and obturator distribution. The SLN %ID ranged from 0.07 to 2.40 % (mean 0.744 % ± 0.641 %); SLN ex vivo count rate ranged from 88 to 2,175 cpm (mean 896 ± 715 cpm); and the SLN standardize uptake values (SUVs) ranged from 13 to 237 (mean 79 ± 67).There was a high concordance of PET-CT imaging to SLN activity, with sensitivity of 93 %. In this feasibility study, pelvic SLNs attained SUVs within 60 min. PET/CT effectively identified SLNs with good anatomic specificity, and radioactivity by hand-held detection and scintillation counts demonstrated high concordance with preoperative imaging. Gallium-68-labaled tilmanocept was highly specific for sentinel nodes. Image-guided tumor resection and lymphadenectomy may become a promising future application in urologic oncology and warrants further investigation.

Pelvic lymph node dissection for patients with elevated risk of lymph node invasion during radical prostatectomy: comparison of open, laparoscopic and robot-assisted procedures

BACKGROUND AND PURPOSE

Published outcomes of pelvic lymph node dissection (PLND) during robot-assisted laparoscopic prostatectomy (RALP) demonstrate significant variability. The purpose of the study was to compare PLND outcomes in patients at risk for lymph node involvement (LNI) who were undergoing radical prostatectomy (RP) by different surgeons and surgical approaches.

PATIENTS AND METHODS

Institutional policy initiated on January 1, 2010, mandated that all patients undergoing RP receive a standardized PLND with inclusion of the hypogastric region when predicted risk of LNI was ≥ 2%. We analyzed the outcomes of consecutive patients meeting these criteria from January 1 to September 1, 2010 by surgeons and surgical approach. All patients underwent RP; surgical approach (open radical retropubic [ORP], laparoscopic [LRP], RALP) was selected by the consulting surgeon. Differences in lymph node yield (LNY) between surgeons and surgical approaches were compared using multivariable linear regression with adjustment for clinical stage, biopsy Gleason grade, prostate-specific antigen (PSA) level, and age.

RESULTS

Of 330 patients (126 ORP, 78 LRP, 126 RALP), 323 (98%) underwent PLND. There were no significant differences in characteristics between approaches, but the nomogram probability of LNI was slightly greater for ORP than RALP (P=0.04). LNY was high (18 nodes) by all approaches; more nodes were removed by ORP and LRP (median 20, 19, respectively) than RALP (16) after adjusting for stage, grade, PSA level, and age (P=0.015). Rates of LNI were high (14%) with no difference between approaches when adjusted for nomogram probability of LNI (P=0.15). Variation in median LNY among individual surgeons was considerable for all three approaches (11-28) (P=0.005) and was much greater than the variability by approach.

CONCLUSIONS

PLND, including hypogastric nodal packet, can be performed by any surgical approach, with slightly different yields but similar pathologic outcomes. Individual surgeon commitment to PLND may be more important than approach.

Robotic-assisted laparoscopic prostatectomy for high-risk prostate cancer: technical considerations and review of the literature

Men with high-risk prostate cancer are at significant risk of progressive, symptomatic disease leading to metastases or death from prostate cancer. Surgery-specifically robotic-assisted laparoscopic prostatectomy (RALP)-is increasingly being considered as a key component of a multimodal strategy to treat these patients. Herein, we review key technical considerations of performing RALP with bilateral pelvic lymphadenectomy in men with high-risk disease. Recent literature supporting the increasing role of surgery either alone or in combination with adjuvant therapies to treat men with high-risk prostate cancer is also reviewed.

Role of surgery in high-risk localized prostate cancer

Men with high-risk localized prostate cancer (PCa) remain a challenge for clinicians. Until recently, surgery was not the preferred approach, in part because risk of subclinical metastatic disease, elevated rates of positive surgical margins, absence of randomized studies, and suboptimal cancer control did not justify the morbidity of surgery. No randomized data comparing surgery with radiation therapy are yet available. Data for and comparisons between treatment options should therefore be analyzed with extreme caution.When selecting the best treatment for patients with clinically localized high-risk PCa, considerations should include the life expectancy of the patient, the natural history of PCa, the curability of the disease, and the morbidity of treatment. High-grade PCa managed with noncurative intent greatly reduces life expectancy, but overall, it must also be remembered that radical prostatectomy (RP) and radiotherapy (RT) appear to have similar effects on quality of life. In this population, RP necessitates an extended pelvic lymph node dissection (PLND), but in selected cases, nerve-sparing is a therapeutic possibility and may offer a significant advantage over rt in terms of local control and-although absolutely not yet proved-maybe even in survival. One clear advantage is the ease of administering adjuvant or salvage external-beam rt (EBRT) after rp; conversely, salvage rp after failed EBRT is an exceedingly difficult surgery, with major complications. Surgery therefore has its place, but must be considered in the context of multimodality treatment and the risk of micrometastatic disease. Awaited trial results will help to further refine management in this group of patients.

Temporal trends and predictors of pelvic lymph node dissection in open or minimally invasive radical prostatectomy

BACKGROUND

Pelvic lymph node dissection (PLND) is an important component of prostate cancer staging and treatment, especially for surgical patients who have high-risk tumor features. It is not clear how the shift from open radical prostatectomy (ORP) to minimally invasive radical prostatectomy (MIRP) has affected the use of PLND. The objectives of this study were to identify predictors of PLND and to assess the impact of surgical technique in a contemporary, population-based cohort.

METHODS

In Surveillance, Epidemiology, and End Results (SEER) cancer registry data linked with Medicare claims, the authors identified men who underwent ORP or MIRP for prostate cancer during 2003 to 2007. The impact of surgical approach on PLND was evaluated, and interactions were examined between surgical procedure, prostate-specific antigen (PSA), and Gleason score with the analysis controlled for patient and tumor characteristics.

RESULTS

Of 6608 men who underwent ORP or MIRP, 70% (n = 4600) underwent PLND. The use of PLND declined over time both overall and within subgroups defined by procedure type. PLND was 5 times more likely in men who underwent ORP than in men who underwent MIRP when the analysis was controlled for patient and tumor characteristics. Elevated PSA and biopsy Gleason score, but not clinical stage, were associated with a greater odds of PLND in both the ORP group and the MIRP group. However, the magnitude of the association between these factors and PLND was significantly greater for patients in the ORP group.

CONCLUSIONS

PLND was less common among men who underwent MIRP, independent of tumor risk factors. A decline in PLND rates was not fully explained by an increase in MIRP. The authors concluded that these trends may signal a surgical approach-dependent disparity in prostate cancer staging and therapy.