Background & objective: Study of sentinel lymph node(SLN) in cervical cancer has been initiated since recent years, and there are still a lot of unknown factors about SLN identification in cervical cancer. This study was to investigate influential factors of identifying SLN with methylene blue in cervical cancer.
Methods: For 41 patients with cervical cancer enrolled from Jun. 2002 to May 2003, 2-4 ml of methylene blue was injected into cervix at 4-6 sites around the tumor about 90-400 min before operation. The blue-dyed lymph node (BDLN) was considered as SLN. HE staining in step sections, and immunohistochemistry were applied to detect SLN. The influential factors of using methylene blue to detect SLN in cervical cancer were assessed based on the identification rate of SLN, and its false negative rate.
Results: SLNs were detected in 31 of 41(75.6%) patients with cervical cancer of stage Ib1-IIb. A total of 85 SLNs were identified,and most frequently located in obturator fossa. SLNs were successfully detected in 20 of 23 (87.0%) patients who had no preoperative radiotherapy or chemotherapy, while in only 11 of 18 (61.1%) patients who had preoperative radiotherapy and/or chemotherapy. SLNs were detected in only 17 of 27(63.0%) patients who were injected with 2-3 ml of methylene blue, while in all of 14 patients whose dose was 3.4-4 ml. Eight patients were confirmed of lymph node metastases by pathology.
Conclusions: The dose of methylene blue recommended to detect SLN in cervical cancer is 3-4 ml. SLN varies in different sites, but most frequently located in obturator fossa.