Utility of GATA3 immunohistochemistry for diagnosis of metastatic breast carcinoma in cytology specimens.

BACKGROUND: GATA3 as a diagnostic marker of metastatic breast carcinoma in cytology specimens has not been fully established.

METHODS: Metastatic breast carcinoma was assessed for GATA3, mammaglobin, and GCDFP-15 immunohistochemistry on cell blocks. GATA3 was scored by intensity (0, negative; 1, weakly positive; 2, moderately positive; 3, strongly positive), and area (0-100%). Mammaglobin (MMG) and GCDFP-15 staining was scored qualitatively (positive vs. negative). Results were correlated with specimen type (fine-needle aspiration vs. body fluid), breast prognostic markers estrogen receptor (ER), progesterone receptor (PR), Her-2/Neu (Her2), and Ki67, and with each other. Statistical significance was determined by chi-squared test and ANOVA for numerical variables. Alpha was set as 0.05. A total of 40 CB specimens containing metastatic breast carcinoma were studied.

RESULTS: GATA3 was positive in 32 (80%) cases. All ER-positive cases (n = 25) were positive for GATA3. Conversely, all GATA3-negative cases (n = 8) were triple-negative breast cancers. On qualitative univariate analysis, GATA3 was statistically associated with ER (P = 0.0001), and PR (P = 0.0468). GATA3 intensity was statistically associated with ER (P ≤ 0.0001), PR (P = 0.0157), Her2 (P = 0.0256), and cancer category (P = 0.0127). GATA3 staining was statistically associated with ER (P ≤ 0.0001), PR (P = 0.0160), Her2 (P = 0.0451), and cancer category (P = 0.0002). MMG and GCDFP-15 were directly compared to GATA3 in 35 samples. The sensitivity was 86% for GATA3, 26% for MMG, and 14% for GCDFP-15.

CONCLUSION: GATA3 is a more sensitive diagnostic marker of metastatic breast carcinoma in CB samples than MMG and GCDFP-15.