Indeed, PGs including syndecans, glypicans, perlecan, versican, biglycan and decorin showed the potential to be promoters or suppressors of cancer, with local effects on invasion, and have a significant modulating effect on BC subtypes or the prognosis and therapeutic response and may potentially serve as new biomarkers for stratification and liquid biopsy candidates. This evidence concerns the gene HSPG2 and breast cancer.