1. ¹Institute of Pathology, Klinikum Grosshadern, Ludwig-Maximilians University, Munich, München, Germany
2. ²Department of Gynaecology and Obstetrics, Klinikum Grosshadern, Ludwig-Maximilians University, Munich, München, Germany

Correspondence: G Peiró, Pathology Department, Hospital General Universitari d'Alacant, C/ Pintor Baeza s/n, 03010-Alacant, Spain. E-mail: peiro_glo@gva.es

Received 14 November 2002; Revised 23 April 2003; Accepted 16 September 2003; Published online 30 January 2004.

Abstract

Fluorescence in situ hybridization (FISH) is the most widely used technique to detect HER-2/neu gene amplification; however, it is only available in some institutions. In contrast, chromogenic in situ hybridization (CISH) can be evaluated by routine light microscopy. In endometrial carcinoma there are few data concerning HER-2/neu status and prognosis. Therefore, we determined HER-2/neu gene status by CISH using a digoxigenin-labelled probe on 60 formalin-fixed paraffin-embedded endometrial carcinomas. The data were compared with the immunohistochemistry of HER-2/neu (A0485, TAB250), p53, Ki-67, clinicopathological factors, and survival. By conventional light microscopy, HER-2/neu amplification (6 copies >50% cancer cells) was detected in 14% (8/59) tumours, HER-2/neu overexpression (>10% cells moderate/strong complete membrane staining) in 22% (13/60) for A0485, and 18% (11/60) for TAB250, p53 (>10% +cells) in 61% (36/59), and Ki-67 (>50% +cells) in 50% (30/60). Discordant cases for CISH and immunohistochemistry, as well as all (2+) were further analysed by FISH (Vysis). Among 10 cases (2+) and not amplified by CISH, two showed low-level amplification by FISH. Significant correlation was found between amplification and protein overexpression (P0.001), and a trend with nonendometrioid type, higher grade, and older age. A better outcome (Kaplan–Meier) was observed for patients with nonamplified (1–5 copies per nucleus) or low-level (6–10 copies) amplification tumours, low Ki-67 expression, age <50 years, endometrioid type, low FIGO (International Federation of Obstetrics and Gynaecology) grade and stage, superficial myometrial infiltration, and no lymph–vascular invasion (P0.036), but only as a trend for HER-2/neu protein negative (P=0.13). Cox analysis revealed age, FIGO grade and stage, myometrial infiltration, and lymph–vascular invasion to be independent prognostic factors (P0.05), and a trend for HER-2/neu gene copy number (0.18). In endometrial carcinoma, HER-2/neu gene status can be readily assessed by CISH in routine clinical practice, and it gives more prognostic information than HER-2/neu by immunohistochemistry. FISH analysis in (2+) cases but negative by CISH may detect additional tumours with low-level amplification.