HER-2 Immunohistochemical Expression in Bone Sarcomas: A New Hope for Osteosarcoma Patients

BACKGROUND: Osteosarcoma and chondrosarcoma, remain the most common primary bone tumours. Questions have been raised about the prognostic influence of HER-2 in bone sarcomas, but so far the results have been debatable. The her-2 expression is possibly a predictor of chemotherapy response. AIM: In this study, we investigated the extent of HER-2 expression in bone sarcomas, and attempted to correlate it with pertinent variables that will help to provide better treatment options, especially for metastatic ones. MATERIAL AND METHODS: Fifty-two cases of bone sarcomas (32 osteosarcoma cases and 20 chondrosarcoma ones) were studied for HER-2 immunohistochemical expression then correlation with all available clinicopathologic features was done. RESULTS: Most of the osteosarcoma cases exhibited membranous staining (78.1%). Strong staining was observed (score 3+) in 34.4%; while 21.9% showed moderate staining (score 2+); and 21.9% displayed weak staining (score 1+), on the other hand, no staining was detected in 7 out of 32 cases (21.9%) (score 0). As regards chondrosarcoma, the absence of staining in all examined cases was noted. Immunohistochemical HER-2 overexpression correlated significantly with osteosarcoma site with P value = 0.004, with variation relating HER-2 intensity score to the site of osteosarcoma (P = 0.051). A statistically significant negative correlation was detected between HER-2 expression and the presence of metastasis at time of diagnosis (P = 0.006), A significant correlation was also found regarding HER-2 score and presence of metastasis with P value = 0.046 as more than half of cases with no metastasis at diagnosis (17/28 cases, 60.7%) showed positive intensity score. A statistically significant correlation was detected between HER-2 expression and patients’ age (P = 0.044). Also, HER-2 expression significantly correlated to histopathological detection of fibrous tissue, with P value = 0.033. Higher scores of HER-2 expression were associated with a significantly better differentiation (P = 0.038) since detection of wide areas of osteoid were associated with higher HER-2 scores. CONCLUSION: Further research would still be needed to delineate HER-2 role being a new hope for therapeutic targeting in bone sarcoma patients, mainly osteosarcoma in contrast to chondrosarcoma that didn’t express HER-2 at all.