Since the aim of this study was to evaluate the aggressiveness of breast cancers expressing both progranulin and the receptor sortilin, the material was subdivided into four groups based on progranulin and sortilin co-expression: 1; low progranulin/low sortilin, 2; low progranulin/high sortilin, 3; high progranulin/low sortilin and 4; high progranulin/high sortilin (see Additional file 2: Table S3). This evidence concerns the gene SORT1 and breast cancer.