Forkhead box (FOX) proteins are family of transcriptional factors and regulate cell growth and differentiation as well as embryogenesis and longevity. Previous studies have demonstrated that several FOX members regulate growth or metastasis of breast carcinoma, but clinical significance of total FOX members remains unclear. We first examined associations between expression of 40 FOX genes and TNM status of 19 breast carcinoma using microarray data. Subsequently, we immunolocalized FOXI1 in 140 breast carcinomas and evaluated its clinicopathological significance. In the microarray analysis, we newly identified that gene expression of FOXI1 was most pronouncedly linked to metastasis of the breast carcinoma among the FOX members examined. However, clinicopathological significance of FOXI1 has not been examined in the breast carcinoma. FOXI1 immunoreactivity was positive in 44 out of 140 (31%) of breast carcinomas, and it was significantly associated with stage, lymph node metastasis and distant metastasis. The FOXI1 status was significantly associated with worse prognosis of the breast cancer patients, and it turned out to be an independent prognostic factor for both distant disease-free survival and breast cancer-specific survival. These findings suggest that FOXI1 plays important roles in the metastasis of breast carcinoma and immunohistochemical FOXI1 status is a potent prognostic factor.

叉头盒 (FOX) 蛋白是转录因子家族，调节细胞生长和分化以及胚胎发生和寿命。以前的研究表明，几个 FOX 成员调节乳腺癌的生长或转移，但总 FOX 成员的临床意义尚不清楚。我们首先使用微阵列数据检查了 40 个 FOX 基因的表达与 19 个乳腺癌的 TNM 状态之间的关联。随后，我们在 140 例乳腺癌中免疫定位 FOXI1 并评估其临床病理学意义。在微阵列分析中，我们新发现在所检查的 FOX 成员中，FOXI1 的基因表达与乳腺癌的转移最显着相关。然而，尚未在乳腺癌中检查 FOXI1 的临床病理学意义。FOXI1 免疫反应性在 140 例乳腺癌中的 44 例（31%）呈阳性，并且与分期、淋巴结转移和远处转移显着相关。FOXI1 状态与乳腺癌患者较差的预后显着相关，它被证明是远处无病生存和乳腺癌特异性生存的独立预后因素。这些发现表明 FOXI1 在乳腺癌转移中起重要作用，免疫组织化学 FOXI1 状态是一个有效的预后因素。结果证明它是远处无病生存率和乳腺癌特异性生存率的独立预后因素。这些发现表明 FOXI1 在乳腺癌转移中起重要作用，免疫组织化学 FOXI1 状态是一个有效的预后因素。结果证明它是远处无病生存率和乳腺癌特异性生存率的独立预后因素。这些发现表明 FOXI1 在乳腺癌转移中起重要作用，免疫组织化学 FOXI1 状态是一个有效的预后因素。