SLN biopsy for staging endometrial cancer
Rossi EC, Kowalski LD, Scalici J, et al. A comparison of sentinel lymph node biopsy to lymphadenectomy for endometrial cancer staging (FIRES trial): a multicentre, prospective, cohort study. Lancet Oncol. 2017;18(3):384-392.
Surgery is the cornerstone of treatment for most gynecologic cancers. The widespread use of minimally invasive surgical techniques and the introduction of less radical procedures for gynecologic cancers have helped reduce surgical morbidity.
For endometrial cancer, the role of lymphadenectomy is controversial. Data from prospective trials of this procedure suggest an association with increased morbidity and long-term sequelae, such as lymphedema, and no association with improved survival.5,6
SLN biopsy is an important advance and a potential alternative nodal evaluation method that may be associated with decreased morbidity. In this more limited assessment technique, the first nodal drainage basins of a tumor are identified and removed for pathologic evaluation.
Accuracy of SLN biopsy in endometrial cancer was the subject of Rossi and colleagues' recent large prospective multicenter study, the Fluorescence Imaging for Robotic Endometrial Sentinel lymph node biopsy (FIRES) trial.
Details of the study
Rossi and colleagues conducted the FIRES trial to estimate the sensitivity of SLN biopsy in detecting nodal metastases in women with stage I endometrial cancer. Patients (N = 385) from 10 US sites were enrolled in the study. SLN evaluation was performed after cervical injection of indocyanine green followed by robotic-assisted hysterectomy. After identification of the SLN, participants underwent pelvic lymphadenectomy. Performance of para-aortic lymphadenectomy was optional.
Mapping of the SLN was feasible in 86% of patients, including bilateral mapping in 52%. Twelve percent of the participants had nodal metastases. SLN biopsy had a sensitivity of 97% in women who had identification of the SLNs. Similarly, the negative predictive value was high, 99.6%. The procedure was associated with acceptable short-term toxicity with adverse events in 9% of study participants. Common complications included neurologic complications, respiratory distress, nausea and vomiting, and, in 3 patients, bowel injury.
Accurate detection of nodal metastases. Results of the study suggest SLN biopsy is accurate in detecting nodal metastases in women with endometrial cancer. Although long-term toxicity was not examined, other work suggests the lymphedema rates associated with SLN biopsy may be lower than those of lymphadenectomy. While the study described impressive performance characteristics, there remain technical challenges. Even among skilled surgeons trained for the protocol, there was no nodal mapping in nearly half of the women with endometrial cancer. Women without node mapping require full lymphadenectomy thus negating the possible benefits of the procedure.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Given the high accuracy of SLN mapping in endometrial cancer, the procedure likely will become the standard of care for nodal evaluation by gynecologic oncologists.