Further studies are clearly needed to understand the biological implications of the ECM3 signature in differentiated versus undifferentiated breast carcinomas, and to verify the good performance of the 4-gene score (COL1A2, COL5A2, SPARC, LAMA4) in discriminating ECM3 tumors, thus validating the role of ECM3 molecular marker. This evidence concerns the gene COL5A2 and breast carcinoma.