Immunohistochemical detection of HER2 in ovarian cancer.

<p><b><i>A.</i></b> Immunostaining showing regional diversity of HER2 expression in high-grade papillary serous ovarian adenocarcinoma. HER2 expression levels were graded in a 0–3 scale (score 0 = undetectable, score 3 = strong staining). Original magnification was 200×. <b><i>B.</i></b> Heatmap illustration of HER2 expression level in 50 primary and metastatic ovarian carcinoma cases, as scored by IHC staining. <b><i>C.</i></b> Frequency distribution of sites expressing HER2 at levels ranging from score 0 to 3. The mean number of evaluated sites for cases with undetectable or detectable HER2 expression was similar (4.2 vs. 3.7 respectively; <i>P</i> = 0.19). <b><i>D.</i></b> Frequency distribution of either primary or metastatic sites expressing HER2 at levels ranging from score 0 to 3. A greater frequency of primary tumor sites expressed HER2 (36%; 30/84) compared to metastatic sites (24%; 27/111) and had a higher mean HER2 expression score (0.37 <i>vs.</i> 0.21, <i>P</i> = 0.04). No statistically significant difference was observed comparing the expression levels among the primary and metastatic sites that expressed HER2 at any level (1.03 <i>vs.</i> 0.86, <i>P</i> = 0.26). <i>P</i> values were calculated using unpaired student’s t-test analysis.