Cytodifferentiation and clinical outcome after chemotherapy and radiation therapy for rhabdomyosarcoma (RMS).
BACKGROUND: Second-look surgery after therapy for rhabdomyosarcoma (RMS) may yield prognostic information regarding tumor responsiveness to treatment. Favorable outcome is suggested by tumor cells which have undergone maturation (cytodifferentiation).PROCEDURE: Specimens from patients treated on Intergroup RMS Study-IV (IRSG-IV) were studied before and after treatment. All patients received chemotherapy and most received radiation therapy. Post-treatment specimens were graded according to the quantity of tumor showing cytodifferentiation (0 = absent, 1 = mild, 2 = moderate, 3 = extensive). Proliferative activity by MIB-1, topoisomerase II-alpha, and p53 protein expression were measured. RESULTS: 19/31 cases from IRSG-IV were adequate for analysis. Six out of nineteen patients failed therapy within 1.3 years of treatment. Grade 3 cytodifferentiation was present in 10 cases (2 BRMS, 8 ERMS); none failed therapy. Grade 2 cytodifferentiation was present in 5 cases (1 ERMS, 2BRMS, 2ARMS); 2 patients with ARMS failed therapy. Grade 0-1 cytodifferentiation was present in 4 cases (1 ERMS and 3 ARMS); all failed therapy. Proliferative activity by MIB-1 and topoisomerase II-alpha immunohistochemistry decreased or was unchanged after treatment for all ERMS/ BRMS, and 4/5 cases of ARMS. p53 immunohistochemistry showed no consistent pattern of reactivity. Sparse persistent tumor cells were present in 9/10 ERMS, 3/4 BRMS, 5/5 ARMS. CONCLUSIONS: Extensive cytodifferentiation is more commonly seen in ERMS/ BRMS compared with less evidence for cytodifferentiation in ARMS suggesting fundamentally different mechanisms of cellular response to therapy in RMS. Sparse persistent tumor cells in post treatment ERMS/ BRMS specimens does not appear to affect outcome.[1]References
- Cytodifferentiation and clinical outcome after chemotherapy and radiation therapy for rhabdomyosarcoma (RMS). Smith, L.M., Anderson, J.R., Coffin, C.M. Med. Pediatr. Oncol. (2002) [Pubmed]
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