In conclusion, our present research constructed a novel 6-gene signature (SQSTM1, GDF9, LINC01125, PTGS2, GVINP1, and TMEM64) by feature importance score and used an XGBoost model to predict the metastatic status in breast cancer (AUC = 0.82, higher than the previous studies to our knowledge). This evidence concerns the gene GDF9 and breast cancer.