SND1 expression in breast cancer tumors is associated with poor prognosis.

Staphylococcal nuclease domain-containing 1 (SND1) expression is crucial for breast cancer metastasis; however, the clinical implications of SND1 expression in breast cancer remain unclear. This study investigated the relationship of SND1 protein expression both with metastasis and the prognoses of 144 breast cancer patients over a 10-year follow-up. Chi-square tests revealed that the percentages of positive SND1 expression in breast cancer tumors were significantly associated with larger tumor size (>2 cm, P = 0.043), higher clinical TNM stage (P = 0.003), and positive lymph node metastasis (P = 0.001). Breast cancer patients with positive SND1 expression had a significantly shorter overall survival and disease-free survival than those with negative SND1 expression (P < 0.01). Multiple Cox regression analysis indicated that SND1 expression is an independent risk factor for shorter disease-free survival (hazard ratio = 1.97, P = 0.014). The percentages of SND1 expression in metastatic breast cancers were significantly higher than that in primary tumors in 30 patients with advanced breast cancer (P = 0.016). Therefore, SND1 protein expression is significantly associated with breast cancer metastasis and may serve as a biomarker for prognosis of breast cancer patients.