Presentation Authors: Lluís Fumadó*, Antoni Mestre-Fusco, Jose María Abascal, Marc Costa, Nuria Juanpere, Josep Lloreta-Trull, Segri Vidal-Sicart, Lluís Cecchini, Barcelona, Spain
Introduction: Extended pelvic lymphadenectomy (ePLND) is the best staging procedure for lymph node involvement in pacients with prostate cancer, with controversial evidence regarding oncological benefits. In this setting, Sentinel lymph node biopsy may play a role in tailoring the surgery, but the best way to perform it is still controversial. We explored how useful could be to inject 99mTc-nanocolloid only to the index lesion.
Methods: A prospective study has been performed between June 2016 and September 2018. It involved 33 patients (median age 67 year-old) diagnosed with localised intermediate or high-risk prostate cancer with >5% in MSKCC nomogram for lymph node involvement. Those patients all had an MRI with an index lesion, and pathologically comfirmed.The day before surgery a radiotracer (240-30 MBq in 0.6 cc volume) was injected only to the index lesion and its peripheral area through cognitive-fusion technique guided by transrectal ultrasound (2-4 injections). A lymphoscintigraphy was subsequently performed with planar images taken at 30 minuts and 3-4 hours post-injection.The surgical procedure included the laparoscopic radical prostatectomy (LP) with sentinel lymph node (SLN) biopsy and ePLND. SLN was intraoperatively detected by a gamma probe.
Results: All patients were cT1-T3 N0, ISUP grade 2-5. The final pathology demonstrated 11(33.3 %) pT2, 17(51.5%) pT3a, and 5(15.2%) pT3b, with 24(72.7%) pN0 and 9(27.3%) pN1. Lymph node dissection included 16.3 lymph nodes per patient (IQR 12-20), with 3.3 SLN (IQR 2-4.5). Mean surgical time for LP + SLN + ePLND was 208 min (IQR 180-240) with 3% transfusion rate (1/33).SLN biopsy was positive in 9 patients (27.3%). None of pathologically negative SLN resulted in a pN1; this represents a PPV and NPV of 100%. Sensitivity and specificity were also 100%. FN was 0% and FP 6% (two cases with SLNs containing metastases outside the ePLND template while the ePLND template did not reveal any metastases). Diagnostic yield was 94% and non diagnostic rate 6%. At a lesion level, a total of 543 lymph nodes were harvested, 104(19.1%) were SLN, 10(9.6%) outside the ePLND area. In total, 22(4%) were positive, 14 within the SLNs and 8 in the ePLND, leading in a 63.6% of metastasis in SN only.
Conclusions: Radiotracer injection to the prostate index lesion offers promising results and an excellent results for staging in those cases where sentinel lymph node dissection is considered. Negative SLN is a predictor of negative ePLND.