MP51-01: How many lymph nodes could we save in prostate cancer staging lymphadenectomy?

Javier Pérez Ardavín*, Manuel Martínez-Sarmiento, Juan José Monserrat-Monfort, Jose Vicente Sanchez-Gonzalez, Victor Vera-Pinto, Valencia, Spain, Pilar Bello-Arqués, València, Spain, Francisco Boronat-Tormo, César David Vera Donoso, Valencia, Spain

Introduction: Currently, for a correct nodal staging in prostate cancer, an extended pelvic lymph node dissection (ePLND) is required, because diagnostic imaging techniques do not offer enough sensitivity or specificity for lymph nodes (LNs) staging. The objective was to carry out a prospective study to compare the ePLND against the sentinel node technique with 99mTcnanocolloid to evaluate the number of nodes resected.

Methods: We had conducted a prospective study between January 2013 and May 2020. We included patients with a Briganti nomogram-assessed risk equal to or higher to 5% (Briganti nomogram 2012), who were candidates to perform a radical prostatectomy. SN technique with 99mTcnanocolloid was performed using a preoperative SPECT/TC and also a laparoscopic gamma-ray detection probe to increase the sensitivity. All of the patients signed the informed consent form and the study protocol was approved by the ethical committee.

Results: We had included a total of 106 patients, in 4 out of the total the radiotracer did not migrate. The mean PSA initial level was 10,55 (CI95%; 9,15 - 11,94) with a mean age of the patients of 64,59 ( CI95%; 63,29 - 65,89). The average nomogram-assessed risk of lymph affection was 11.98 % (CI95%; 10,07 - 13,88). Evaluating the pathologic outcomes, a total of 2285 LN were analyzed and the mean number of extracted nodes was 21.56 (CI95%; 13.46 - 29.71). As to the SNs, a total of 525 nodes were found and the mean of extracted SNs was 5.17 (IC95%; 1.83 - 8.51), resulting in 77% less, the difference was statistically significant (p < 0.001). SN technique could detect all the patients who had some metastasis with a sensitivity of 100% at the patient level. It should be noted that 777 of LNs were found outside the ePLND template which correlates with 81 patients (78 %). Metastasis at histopathologic evaluation was found in a total of 52 LNs (2 %) which corresponded to 26 patients (25 %). Furthermore, a total of 6 positive nodes (11.53 %) were found outside the ePLND template which belongs to 4 patients (a 3.77 % of the total but signify 15.4 % of the patients with positive LN).

Conclusions: In our series, SN with 99mTcnanocolloid had a sensitivity of 100 % detecting all the patients with LNs metastasis. This technique could remove a total of 77 % fewer lymph nodes than the ePLND, causing less morbidity, surgery time, and overtreatment. Also, SN could reveal LNs outside the ePLND in 78 % of the patients, which could diagnose 4 more patients and 6 more positive nodes than the ePLND.

Source of Funding: none