Aberrant Expression of Tumor Suppressor Proteins in the Ewing Family of Tumors

Abstract Background.—Deregulation of tumor suppressor gene function and abrogation of cell cycle control are common features of malignant neoplasms, but corresponding data on Ewing sarcomas and primitive neuroectodermal tumors are relatively scarce. We studied the expression of 4 tumor suppressor proteins in the Ewing family of tumors (EFTs). Design.—We examined a series of 20 pediatric EFTs for abnormal expression of p16INK4a, p14ARF, p21WAF1, and pRB by immunohistochemical analysis of pretreatment, nondecalcified archival specimens. Clinical follow up was available in all cases (median, 21 months; range, 5–103 months). Five patients presented with metastatic disease, 8 had no evidence of disease at last follow up, and 12 had an adverse outcome (death or progressive tumor posttherapy). Results.—Twelve cases (60%) demonstrated abnormal expression of at least one tumor suppressor protein. There were 11 cases (55%) with loss of p21WAF1 expression, 4 (20%) with down-regulation of p16INK4a, 2 (10%) with absen...