Sentinel-node mapping in endometrial cancer patients: comparing SPECT/CT, gamma-probe and dye

Objective: The aim of this study was to compare preoperative SPECT/CT with gamma-probe and methylene blue-dye (MBD) in the identification of sentinel lymph node (SLN) in early stage endometrial cancer.

Methods: 40 stage-I EC patients (66.7 ± 9.7 years) underwent preoperative lymphoscintigraphy. After about 3 h from Tc-99m-albumin nanocolloid cervical injection, all patients underwent SPECT/CT study. MBD was injected into the cervix just before surgery under general anesthesia. All patients underwent SLN biopsy, hysterectomy, bilateral salpingo-oophorectomy, and radical regional lymphadenectomy. SPECT/CT findings were compared to those of gamma-probe and MBD techniques.

Results: In 2 patients no nodal migration was observed, neither with MBD nor radiotracer. Detection rate of at least one SLN was 90% (36/40 patients) with SPECT/CT, 88% (35/40) intra-operatively with gamma-probe and 80% (32/40) with MBD. Only in 7/40 patients a bilateral migration was obtained with all considered modalities. In particular, bilateral detection was achieved in 26 patients with SPECT/CT, in 24 with gamma-probe and in 10 patients with MBD. The concordance site between SPECT/CT and intraoperative gamma-probe was 73% (29/40 patients: 2 without migration, 21 bilateral and 6 monolateral SLNs); while concordance site with MBD was found in 40% (16/40: 8 bilateral, 6 monolateral SLNs, 2 without SLNs). Overall, 628 LNs were dissected (mean 18 LNs per patient). The median number of SLNs removed was 2 (mean 2.5 per patient). Out of 91 SLNs: 43 were "hot and blue (HB)", 10 were blue only and 38 were hot only. LN metastases rate was 16%: 9/90 SLNs (7 HB, 2 hot only) were positive for metastases in 6 patients. Four non-SLNs were found positive in 3 patients, and all presented concomitant positive SLNs. False negative rate was 0%.

Conclusions: SPECT/CT had the highest detection rate and achieved the highest rate of bilateral mapping, compared to gamma-probe and MDB. SPECT/CT had moderate concordance with gamma-probe, and it can help the intraoperative detection of SLNs providing important information about their anatomic location.