Sentinel lymph node mapping in endometrial cancer: performance of hysteroscopic injection of tracers

Abstract

ObjectiveTo report on the performance of hysteroscopic injection of tracers (indocyanine green (ICG) and technetium-99m (Tc-99m)) for sentinel lymph node (SLN) mapping in endometrial cancer.MethodsSingle-center retrospective evaluation of consecutive patients who underwent SLN mapping following hysteroscopic peritumoral injection of tracer. Detection rate (overall/bilateral/aortic) diagnostic accuracy, and oncologic outcomes were evaluated.ResultsA total of 221 procedures met the inclusion criteria. Mean patient age was 60 (range 28–84) years and mean body mass index was 26.9 (range 15–47) kg/m2 . In 164 cases (70.9%) mapping was performed laparoscopically. The overall detection rate of the technique was 94.1% (208/221 patients). Bilateral pelvic mapping was found in 62.5% of cases with at least one SLN detected and was more frequent using ICG than with Tc-99m (73.8% vs 53.3%; p<0.001). In 47.6% of cases SLNs mapped in both pelvic and aortic nodes, and in five cases (2.4%) only in the aortic area. In eight patients (3.8%) SLNs were found in aberrant (parametrial/presacral) areas. Mean number of detected SLNs was 3.7 (range 1–8). In 51.9% of cases at least one node other than SLNs was removed. Twenty-six patients (12.5%) had nodal involvement: 12 (46.2%) macrometastases, six (23.1%) micrometastases, and eight (30.7%) isolated tumor cells. In 12 cases (46.8%) the aortic area was involved. Overall, 6/221 (2.7%) patients had isolated para-aortic nodes. Three false-negative results were found, all in the Tc-99m group. All had isolated aortic metastases. Overall sensitivity was 88.5% (95% CI 71.7 to 100.0) and overall negative predictive value was 96.5% (95% CI 86.8 to 100.0). There were 10 (4.8%) recurrences: five abdominal/distant, four vaginal, and one nodal (in the aortic area following a unilateral mapping plus side-specific pelvic lymphadenectomy). Most recurrences (9/10 cases) were patients in whom a completion lymphadenectomy was performed. No deaths were reported after a mean follow-up of 47.7 months.ConclusionsHysteroscopic injection of tracers for SLN mapping in endometrial cancer is as accurate as cervical injection with a higher detection rate in the aortic area. ICG improves the bilateral detection rate. Adding lymphadenectomy to SLN mapping does not reduce the risk of relapse.

Paraaortic sentinel lymph node detection in intermediate and high-risk endometrial cancer by transvaginal ultrasound-guided myometrial injection of radiotracer (TUMIR)

“…The detection rate of this technique ranges from 50% to 95% [ 11 35 ]. A recent study has reported a paraaortic SLN detection rate by hysteroscopic injection with radiotracer or ICG similar to the present series [ 30 ]. However, a randomized trial comparing cervical and hysteroscopic injections showed better identification of pelvic SLNs after cervical injection with a non-significant higher detection rate of paraaortic SLNs after hysteroscopic injection [ 36 ].…”

“…This is concordant with the extremely low detection of isolated paraaortic SLNs of less than 1% [ 29 ], which is inferior to the exclusive paraaortic drainage with the TUMIR approach (7.4%). This low percentage is not surprising, since it has been already pointed out that cervical injection does not adequately represent endometrial drainage, because it misses the lymphatic drainage to the paraaortic area [ 30 ]. The uterine corpus has 2 simultaneous lymphatic pathways: the first drainage is through the lymphatic channels together with the uterine vessels to the pelvic LNs -located in the lateral part of the parametrium and/or under the external iliac vein-, and the second drainage goes directly to the paraaortic area through the lymphatic vessels of the gonadal vasculature and the infundibulopelvic ligament [ 31 ], explaining the possibility of having SLNs in both areas independently.…”

“…Thus, bilateral pelvic lymphadenectomy would be required in these cases to avoid undetected pelvic LN metastases. Recently, it has been suggested that paraaortic lymphadenectomy should be considered only in patients in whom paraaortic SLN mapping does not occur [ 2 30 ]. The TUMIR approach would allow avoiding systematic paraaortic LN dissection and its associated morbidity in almost half of patients with SLN mapping.…”

“…Moreover, this last approach is complex and less reproducible compared with the TUMIR method. Hysteroscopic radiotracer injection is performed without local and/or general anesthesia, which may be uncomfortable for the patient [ 30 ]. Although the TUMIR method showed a median moderate score in the pain scale with the application of local anesthesia, it is also performed with the patient awake and this discomfort is not negligible.…”

“…This relatively low percentage of LN involvement highlights that performing systematic pelvic and paraaortic LN dissection, as currently recommended [ 1 ], implies overtreatment in up to 80% of these women at higher risk of LN involvement. Moreover, a recent study has suggested that adding lymphadenectomy to SLN mapping has no survival benefit as it does not reduce the risk of relapse [ 30 ].…”