Sentinel Lymph Node Biopsy in Prostate Cancer Patients: Results From an Injection Technique Targeting the Index Lesion in the Prostate Gland

Abstract

ObjectivesTo determine the accuracy of nodal staging in patients with prostate cancer (PCa) when 99mTc-nanocolloid radiotracer is injected into an index lesion (IL).MethodsThis prospective study was conducted at our institution between June 2016 and October 2020. It included 64 patients with localized PCa with at least a 5% possibility for lymph node involvement in the Memorial Sloan Kettering Cancer Center nomogram, suitable for surgical treatment. All patients underwent magnetic resonance imaging (MRI) with IL and were pathologically confirmed. The day before surgery, transrectal ultrasound-guided injection (TRUS) of 99mTc-nanocolloid into the IL was performed. Surgical procedures included radical prostatectomy (RP), sentinel lymph node biopsy (SLNB), and extended pelvic lymphadenectomy (ePLND). Analysis was performed, including histopathological findings of RP, ePLND, and SLNB. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false negative (FN), false positive (FP), diagnostic yield, and non-diagnostic rate were calculated.ResultsA total of 1,316 lymph nodes were excised, including 1,102 from the ePLND (83.7%) and 214 (16.3%) sentinel lymph nodes (SLN). 26 SLN were dissected outside the ePLND template. The final pathology demonstrated 46 (3.5%) lymph node metastasis, 31 (67.4%) in the SLNB and 15 (32.6%) in the non-SLN ePLND. At the patient level, 18 (28.1%) patients had pN1. With a mean follow-up of 33.1 months, 4/19 (21.1%) pN1 patients had undetectable PSA, and 3/19 (15.8%) had a PSA < 0.1 ng/mL. Lymph node dissection included 20.6 lymph nodes per patient (IQR 15–24.2), with 3.3 SLNB nodes per patient (IQR 2–4.2). PPV and NPV were 100 and 97.8%, respectively. Sensitivity and specificity were 94.4 and 100%, respectively. FN was 5.5% and FP was 4.3%. Diagnostic yields were 95.3% and the non-diagnostic rate was 4.7%.ConclusionRadiotracer injection into the prostate IL offers promising results for staging purposes in cases in which ePLND is considered. Negative SLNB is a predictor of negative ePLND. Patients with a limited burden of nodal metastasis have a significant chance of remaining free of biochemical recurrence at mid-term follow-up.

Sentinel Lymph Node Techniques in Urologic Oncology: Current Knowledge and Application

“…The false-negative (FN) rate was 5.5%, whereby one patient had nodal metastasis, despite negative SLNs. Moreover, only 10 of 18 patients (55.6%) had metastasis to SLNs only [80]. Some studies showed similar results, indicating high accuracy rates, but many of them also revealed low detection rates of all metastatic LNs, preventing the application of SLND only [102][103][104][105][106][107].…”

“…SLNB in PCa was first described by Wawroschek et al in 1999, and then investigated by the same group, as well as Rudoni et al [77][78][79]. Now, almost 25 years later, SLNB is still considered an experimental procedure in PCa [80].…”

Sentinel Lymph Node Biopsy in Prostate Cancer: An Overview of Diagnostic Performance, Oncological Outcomes, Safety, and Feasibility

“…Data collected from the included manuscripts accounted for a total of 2586 patients. Regarding SLN tracer selection, a total of 10 papers reported the use of technetium 99m-nanocolloids (99mTc-NC) [18,19,29,33,35,[37][38][39][40][41], 6 papers of "free" indocyanine green (ICG) [17,22,28,30,32,44], 3 papers of "hybrid" ICG-99mTC-NC tracer [23,24,31], 4 papers superparamagnetic of iron oxide nanoparticles (SPION) [25][26][27]36], 2 papers of PSMA radiotracer [20,21], 1 paper of technetium 99m-sulfur [34], 1 paper of technetium 99mphylate [42], and 1 paper of technetium 99m human serum albumine (HAS) [43]. Two groups combined the use of 99mTc-NC and intraoperative ICG within the same cohort [23,24].…”

“…Two groups combined the use of 99mTc-NC and intraoperative ICG within the same cohort [23,24]. Regarding tracer administration, 11 papers reported an intraprostatic injection template [17][18][19]22,24,25,27,29,37,38,43]. Intra-/peri-lesional administration was performed in two reports [18,29].…”

“…Regarding tracer administration, 11 papers reported an intraprostatic injection template [17][18][19]22,24,25,27,29,37,38,43]. Intra-/peri-lesional administration was performed in two reports [18,29]. The mean number of dissected LNs from SNB templates was collected, with an overall mean of 4.9 LNs dissected per SNB template.…”