Background & objective: Sentinel lymph node (SLN) identification has been increasingly used in the treatment design of a variety of solid tumors, particularly breast cancer and melanoma. A negative SLN predicts the absence of tumor metastases in the regional lymph nodes with high accuracy. This study was to investigate the clinical value of combined isotope-dye technique for detecting SLN, and to evaluate the accuracy of SLN in predicting the pelvic lymph nodes status in patients with early stage cervical cancer.
Methods: A total of 27 patients with early stage cervical cancer,scheduled for radical hysterectomy and total pelvic lymphadenectomy, were eligible for the study. Lymphoscintigraphy was performed with injection of radioactivity isotope (99m)Tc-labeled dextran ((99m)Tc-DX) into the uterine cervix 16 h before surgery. Methylthioninium (4 ml) was injected into the same points as (99m)Tc-DX during surgery, and the patients underwent lymphatic mapping with a handheld gamma-detecting probe. After resection of SLNs, standard radical hysterectomy with pelvic lymph node dissection was performed. All removed lymph nodes, including the SLNs, were examined by routine histopathology. The histopathologic results of SLNs and non-SLNs were compared.
Results: The detection rates of SLN were 96.3% by blue dye method, and 100% by radiolabeled tracer or combined isotope-dye. Blue dye method identified 61 SLNs, radiolabeled tracer identified 69 SLNs, and combined isotope-dye identified 70 SLNs. Preoperative SPECT/CT fusion images detected 4 SLNs in the parametrium. Seven (25.9%) patients had lymph node metastasis. The sensitivity, accuracy, negative predictive value, and false negative rate of SLN detection were 85.7% (6/7), 96.3% (26/27), 95.2% (20/21), and 14.3% (1/7), respectively.
Conclusions: SPECT/CT imaging not only is superior to planar imaging in detecting SLN but also enables precise localization of SLNs. The combined isotope-dye method can improve the accuracy of SLN detection. SLN detection can accurately predict the pelvic lymph nodes status in early stage cervical cancer.