Introduction

The stage migration phenomenon and the introduction of robot-assisted radical prostatectomy (RARP) might have changed the characteristics of prostate cancer (PCa) patients in terms of risk and features of lymph node invasion (LNI).

Methods

5,328 PCa patients treated with open radical prostatectomy or RARP and an extended pelvic lymph node dissection (ePLND) between 2005 and 2016 were identified. All nodal specimens were retrieved in multiple packages according to the anatomical location and evaluated by high-volume uro-pathologists. The year-per-year trend of pathologic characteristics was reported. Multivariable (MVA) logistic regression analyses tested the impact of year of surgery and RARP on the risk of LNI and on the site of nodal invasion after adjusting for confounders.

Results

Overall, 3,159 (59.3%) and 2,169 (40.7%) patients were treated with ORP and RARP. Median number of nodes removed increased over time both for ORP and RARP (from 15 to 18 and from 9 to 21; all P<0.001). The proportion of patients with LNI was 11.2% and increased from 10.8 to 16.3% between 2005 and 2015 (P<0.001). Patients treated in more recent years were at higher risk of LNI (P=0.001). In 585 individuals with LNI, median number of positive nodes and maximum diameter of metastases were 2 and 5 mm and did not change over time (P≥0.5). Overall, 44.8, 73.3, and 15.4% patients with LNI had involvement of the external iliac, obturator, and internal iliac nodes. While the proportion of positive internal iliac nodes increased (from 10 to 37.5%; P<0.001), the rate of obturator nodes involvement decreased (from 80.7 to 42.5%; P<0.001). The proportion of positive internal iliac nodes was higher among those treated with RARP (20.3 vs. 14.1%; P=0.05). At MVA, year of surgery and RARP were associated with a higher probability of positivity in the internal iliac nodes and a lower probability of LNI in the obturator nodes (all P<0.001). No differences were recorded over time and according to the technique in the proportion of positive external iliac nodes (from 43.9 to 52.5%; P=0.6). Overall, 5.5 and 8.9% patients had LNI in the presacral and common stations. The proportion of men with positive presacral and common iliac nodes did not change over time and according to the technique (P≥0.1).

Conclusions

We observed an increased proportion of patients with positive internal iliac lymph nodes over time. This was likely related to the introduction of RARP, which may allow for more precise dissection in this area and a more accurate nodal staging.

Funding

none