Comparison of lymphoscintigraphy and single photon emission computed tomography with computed tomography (SPECT/CT) for sentinel lymph node detection in endometrial cancer.

Background: Endometrial cancer is the most common gynecologic cancer, and lymph node metastasis is one of the most important prognostic factors. Increasing evidence shows that sentinel lymph node (SLN) mapping is an effective alternative to comprehensive lymphadenectomy. Single photon emission CT with computed tomography (SPECT/CT) is associated with a high SLN detection rate.

Objective: To compare the clinical efficacy of SPECT/CT with that of lymphoscintigraphy in detecting SLNs in patients with endometrial cancer.

Methods: Between May 2014 and October 2018, 151 patients with endometrial cancer were enrolled in this study at the Department of Obstetrics and Gynecology of the Kagoshima University Hospital. Inclusion criteria were patients with endometrial cancer, older than 18 years, and with pre-operative International Federation of Gynecology and Obstetrics (FIGO) staging of I and II. All patients underwent pre-operative CT, and patients with suspected peritoneal dissemination and lymph node metastasis were excluded from this study. Pelvic SLNs were detected by injection of tecnetium-99m-labeled phytate into the uterine cervix. The number and locations of SLNs detected using lymphoscintigraphy and SPECT/CT were evaluated. JMP software (version 14, SAS Institute Inc., Cary, North Carolina, USA) was used for statistical analysis.

Results: A total of 151 patients who underwent pre-operative lymphoscintigraphy and SPECT/CT were included in the study. The median age was 57 years (range 24-79), and the median body mass index was 24.3 kg/m (range 16-40). The final pathology was as follows: 135 (89%) endometrioid carcinoma, 11 (7%) serous carcinoma, one (1%) clear cell carcinoma, and four (3%) other histotypes. Based on SPECT/CT, 204 pelvic SLNs were detected. The bilateral pelvic SLN detection rate was better for SPECT/CT (43% (65/151)) than for lymphoscintigraphy (32% (48/151)) (p<0.0001). The overall pelvic SLN detection rate (at least one pelvic SLN detected) was also better with SPECT/CT (77% (16/151)) vs lymphoscintigraphy (68% (102/151)) (p<0.0001). The distribution of SLN locations detected using SPECT/CT was as follows: external iliac, 91 (45%); obturator, 61 (30%); common iliac, 28 (14%); internal iliac, 19 (9%); para-aortic, 2 (1%); parametrium, 2 (1%), and presacral, 1 (1%). The SLN detection rate using SPECT/CT was significantly worse in patients of advanced age (p<0.0001).

Discussion: Overall and bilateral SLN detection rate was better with SPECT/CT than with lymphoscintigraphy in patients with stage I/II endometrial cancer.