Background Isolated positive para-aortic lymph node metastasis in endometrial cancer is an uncommon event, ranging from 1% to 3%.

Objective Our aim was to evaluate the impact of sentinel lymph node (SLN) mapping on the risk of isolated positive para-aortic lymph node metastasis.

Methods We retrospectively evaluated a series of 426 patients who underwent SLN mapping with at least one SLN detected from January 2013 to December 2021 (SLN group) compared with a historical series of 209 cases who underwent a systematic pelvic and para-aortic lymphadenectomy between June 2007 and April 2015 (LND group). Isolated para-aortic lymph node metastasis recurrences were included in the SLN group analysis.

Results In the SLN group, 168 cases (39.4%) had backup systematic lymphadenectomy, and 56 (13.1%) had positive lymph nodes compared with 34 (16.3%) in LND group (p=0.18). The SLN group had higher rates of minimally invasive surgeries (p<0.001) and presence of lymphovascular space invasion (p<0.001). Moreover, SLN group had fewer other uterine risk factors, such as high-grade tumors (p<0.001), and deep myometrial invasion (p<0.001). We found that SLN mapped outside the pelvis at pre-sacral, common iliac areas, and para-aortic regions in 2.8% (n=12), 11.5% (n=49), and 1.6% (n=7) of cases, respectively. Overall, 52 (12.2%) patients had positive SLNs, and 3 (5.7%) positive SLNs were found outside the pelvis—one in the pre-sacral region, one in the common iliac area, and one in the para-aortic region. An isolated para-aortic lymph node was found in only 2 (0.5%) cases in the SLN group compared with 7 (3.3%) cases in the LND group (p=0.004).

Conclusions SLN protocol accurately predicts lymph node status and may decrease the risk of failed identification of isolated para-aortic lymph node metastasis compared with systematic lymphadenectomy.