Objective To date, there is no universal consensus on which is the optimal ultrastaging protocol for sentinel lymph node (SLN) evaluation in gynecologic malignancies. To estimate the impact of different ultrastaging methods of SLNs on the detection of patients with nodal metastases in early-stage cervical and endometrial cancers and to describe the incidence of low-volume metastases between two ultrastaging protocols.

Methods We retrospectively compared two ultrastaging protocols (ultrastaging-A vs ultrastaging-B) in patients with clinical stage I endometrial cancer or FIGO stage IA-IB1 cervical cancer who underwent primary surgery including SLN biopsy from October 2010 to December 2017 in our institution. The histologic subtypes and grades of the tumors were evaluated according to WHO criteria. Only SLNs underwent ultrastaging, while other lymph nodes were sectioned and examined by routine hematoxylin and eosin (H&E).

Results Overall 224 patients were reviewed (159 endometrial cancer and 65 cervical cancer). Lymph node involvement was noted in 15% of patients with endometrial cancer (24/159): 24% of patients (9/38) with the ultrastaging protocol A and 12% (15/121) with the ultrastaging protocol B (p=0.08); while for cervical cancer, SLN metastasis was detected in 14% of patients (9/65): 22% (4/18) in ultrastaging-A and 11% (5/47) in ultrastaging-B (p=0.20). Overall, macrometastasis and low-volume metastases were 50% and 50% for endometrial cancer and 78% and 22% for cervical cancer. Median size of nodal metastasis was 2 (range 0.9–8.5) mm for the ultrastaging-A and 1.2 (range 0.4–2.6) mm for the ultrastaging-B protocol in endometrial cancer (p=0.25); 4 (range 2.5–9.8) mm for ultrastaging-A and 4.4 (range 0.3–7.8) mm for ultrastaging-B protocol in cervical cancer (p=0.64).

Conclusion In endometrial or cervical cancer patients, the incidence of SLN metastasis was not different between the two different types of ultrastaging protocol.