[1115] Pathologic Ultrastaging of Sentinel Lymph Nodes in Endometrial Cancer

F Khoury-Collado, RA Soslow, MP Murray, ML Gemignani, NR Abu Rustum. Memorial Sloan-Kettering Cancer Center, New York

Background: Sentinel lymph node (SLN) evaluation in patients with endometrial cancer (EMC) has been proposed as an alternative to selective or reflexive lymphadenectomy.
Design: Patients undergoing primary surgery for EMC between 09/2005 and 09/2009 were studied prospectively. SLN mapping was performed using blue dye injection into the cervix in all cases. Additional injection methods included blue dye injection in the uterine findus, and cervical injection of 99m Tc sulfur colloid. SLN were removed followed by regional LN dissection. The pathology protocol for SLN evaluation follows: 2 adjacent 5-μm section were cut at each of two levels 50 μm apart from paraffin blocks lacking metastatic carcinoma appreciable in a routine hematoxylin and eosin (H&E) section. At each level, one slide was stained with H&E and the other with immunohistochemistry (IHC) using the anti-cytokeratin AE1:AE3, as well as one negative control slide, for a total of 5 slides per block. All other non-SLN nodes were examined only by routine H&E. Micrometastasis (MM) was defined as a focus of metastatic cancer ranging from 0.2-2mm. Isoltaed tumor cells (ITC) were defined as metastasis measuring ≤0.2 mm, including the presence of single non-cohesive cytokeratin positive tumor cells.
Results: 153 EMC patients were evaluated. The histologic subtypes were: endometrioid, 122 (80%); serous, 16 (10%); carcinosarcoma, 6 (4%); clear cell, 2 (1%); mixed, 7 (5%). The surgical stages were: stage I, 118 (77%); stage II, 3 (2%); stage III, 31 (205); stage IV, 1 (1%). SLN identification was possible in 131 (86%) cases. A median of 3 SLN (range, 1-14) and 10 non-SLN (range, 0-55) per patient were examined. The total number of patients with positive LNs was 20/153 (15%). In 6/20 (30%) cases with positive LNs, tumor cells were detected only by review of additional sections or IHC on the SLN required by the protocol (3 cases of MM and 3 cases of ITC). The SLN was negative for carcinoma in 3/20 (15%) cases with a positive non-SLN (false negative rate of 15%). All such cases occurred in the hands of surgeons new to the SLN procedure.
Conclusions: Pathologic ultrastaging of SLN removed during the lymphatic mapping for EMC is associated with a high (30%) detection rate of micrometastasis and ITCs that may have otherwise been undetected by routine LN evaluation. The clinical significance of ITCs in EMC requires longer follow-up.
Category: Gynecologic & Obstetrics

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 140, Wednesday Morning


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