Is it time to replace lymphadenectomy with SLN biopsy in early endometrial cancer management?
Sentinel lymph node (SLN) mapping and biopsy is noninferior to systematic lymphadenectomy in detecting LN metastases with <5-percent false negative rate, says Timothy Lim, head of the Department of Gynaecologic Oncology at KK Women’s and Children’s Hospital and associate professor at Yong Loo Lin School of Medicine, National University Singapore.
In his presentation at the Royal College of Obstetricians and Gynaecologists World Congress 2018, Lim claimed that SLN mapping alone could be performed in patients with clinically early grade 1 or 2 endometrial cancer, and that the use of indocyanine green (ICG) fluorescence imaging technique is simpler and not inferior to traditional methods, with cervical being preferred over corporeal injection.
“SLN mapping has been proposed as a technique to identify LN metastases,” Lim said. “It has been used successfully in early breast cancer and vulvar cancer.”
In an unpublished pilot study in Singapore on SLN mapping using ICG fluorescence imaging, Lim and colleagues analysed 35 patients with clinical stage 1 endometrial cancer (29 grade 1, five grade 2 and one grade 3 endometroid adenocarcinoma), with mean LN count of 21 nodes (28 patients). Seven patients chose not to have systematic pelvic lymphadenectomy.
There were three (0–6) SLN identified per patient, with an overall detection rate of 97 percent (34/35). Bilateral, unilateral and no mapping was performed in 31 (88.6 percent), three (8.6 percent) and one (2.9 percent) patients, respectively. The most common SLN location was the exterior iliac artery (55.7 percent), followed by obturator (21 percent), common iliac (18 percent), internal iliac (4 percent) and presacral/low para-aortic (2.9 percent).
Two patients (5.7 percent) had positive bilateral pelvic lymph nodes, and SLN was positive for both participants. Four cases (11.4 percent) were upstaged (two stage 2 and two stage 3C1), and four cases (11.4 percent) had histology upgraded (three grade 2 and one malignant mixed mesodermal tumour).
This study was limited by the small number of participants. In addition, MRI pelvis was not routinely performed and SLN ultrastaging was not carried out.
“Clinical trials are needed to address the significance of isolated tumour cells and the role of SLN in clinically early high-risk/high-grade cancers,” Lim said.
In a recent meta-analysis of 55 eligible studies (n=4,915 women), Smith and her team suggested that SLN mapping was feasible and accurately predicted nodal status in women with endometrial cancer, with current data favouring the use of cervical injection techniques with ICG. [Am J Obstet Gynecol 2017;216:459-476.e10]
“Sentinel lymph mapping may be considered an alternative standard of care in the staging of women with endometrial cancer,” Smith said.
Another study that compared SLN biopsy to lymphadenectomy for endometrial cancer staging found that SLN identified with ICG had a high degree of diagnostic accuracy in detecting endometrial cancer metastases, suggesting that the method could be a safe alternative in the staging of endometrial cancer. [Lancet Oncol 2017;18:384-392]
“Sentinel lymph node biopsy will not identify metastases in 3 percent of patients with node-positive disease, but has the potential to expose fewer patients to the morbidity of a complete lymphadenectomy,” lead author Emma Rossi said.
A sentinel node is the “first LN to receive drainage from the primary tumour” and is likely to “harbour metastases,” according to Lim. “LN status is an important predictor of survival and guides postoperative treatment planning in endometrial cancer management.”