Detection and prognostic significance of isolated tumor cells and micrometastases in pelvic lymph nodes of patients with early ovarian clear cell carcinoma

Abstract

Ovarian clear cell carcinoma (OCCC) accounts for approximately 18% of all epithelial ovarian malignancies in Taiwan and portends a poor prognosis. Here, we sought to investigate whether immunohistochemistry with an anti-pan-cytokeratin antibody cocktail (AE1/AE3) can be used as an adjunct to hematoxylin and eosin (H&E) staining for improving the detection of isolated tumor cells (ITCs) and micrometastasis to pelvic lymph nodes (LNs). We also assessed whether these lesions may predict disease recurrence.Pelvic lymphadenectomy specimens were obtained from 197 patients with stage 1 OCCC who had undergone surgery between 2000 and 2018 from Linkou and Kaohsiung Chang Gung Memorial Hospital. Immunohistochemical staining with AE1/AE3 was applied to a total of 1186 slides. Clusters of metastatic tumor cells, detected immunohistochemically, were classified as ITCs (clusters with diameters of ≤0.2 mm) or micrometastases (tumor cell clusters of >0.2 but ≤2.0 mm). We also assessed the diameter of metastases in patients with positive lymph nodes (stage IIIA1, n = 3, 7 positive nodes).Clusters with a positive AE1/AE3 staining were identified in five (2.53%) of the 197 patients (ITCs, n = 3; micrometastasis, n = 2). Four patients had no evidence of disease recurrence but a patient recurred at follow-up. Metastatic foci of patients with stage IIIA1 disease were all >2.0 mm in size.Immunohistochemical staining with AE1/AE3 can identify micrometastasis or ITCs in LNs missed on routine H&E staining. The role of micrometastasis in predicting recurrent OCCC and implementing on treatment strategies requires further investigation.