Alveolar rhabdomyosarcoma (ARMS) is characterized by one of three translocation states: t(2;13) (q35;q14) producing PAX3-FOXO1, t(1;13) (p36;q14) producing PAX7-FOXO1, or translocation-negative. Tumors with t(2;13) are associated with greater disease severity and mortality than t(1;13) positive or translocation negative patients. Consistent with this fact, previous work concluded that a molecular analysis of RMS translocation status is essential for the accurate determination of prognosis and diagnosis. However, despite this knowledge, most diagnoses rely on histology and in some cases utilize fluorescence in situ hybridization (FISH) probes unable to differentiate between translocation products. Along these same lines, diagnostic RT-PCR analysis, which can differentiate translocation status, is unable to determine intratumoral translocation heterogeneity, making it difficult to determine if heterogeneity exists and whether correlations exist between this heterogeneity and patient outcomes. Using newly developed FISH probes, we demonstrate that intratumoral heterogeneity exists in ARMS tumors with respect to the presence or absence of the translocation product. We found between 3 and 98% of cells within individual tumor samples contained a translocation event with a significant inverse correlation (R² = 0.66, p = 0.001) between the extent of intratumoral translocation heterogeneity and failure-free survival of patients. Taken together, these results provide additional support for the inclusion of the molecular analysis of these tumors and expand on this idea to support determining the extent of intratumoral translocation heterogeneity in the diagnosis of ARMS to improve diagnostic and prognostic indicators for patients with these tumors.

肺泡横纹肌肉瘤（ARMS）的特征在于以下三种易位状态之一： Ť（2; 13）（q35; q14）产生PAX3-FOXO1， Ť（1; 13）（p36; q14）产生PAX7-FOXO1或易位阴性。肿瘤与Ť（2; 13）与 Ť（1; 13）阳性或易位阴性患者。与此事实相符，以前的工作得出结论，RMS易位状态的分子分析对于准确确定预后和诊断至关重要。然而，尽管有这些知识，大多数诊断还是依靠组织学，在某些情况下还是利用荧光原位杂交（FISH）探针无法区分易位产物。同样，可区分易位状态的诊断性RT-PCR分析无法确定肿瘤内易位异质性，从而难以确定异质性是否存在以及该异质性与患者预后之间是否存在相关性。使用新开发的FISH探针，我们证明相对于是否存在易位产物，ARMS肿瘤中存在肿瘤内异质性。我们发现，单个肿瘤样本中有3％到98％的细胞包含易位事件，且具有显着的逆相关性（[R² = 0.66，p= 0.001）在肿瘤内移位异质程度和患者的无衰竭生存之间。综上所述，这些结果为包含这些肿瘤的分子分析提供了额外的支持，并扩展了这一想法，以支持确定ARMS诊断中的肿瘤内易位异质程度，从而改善这些肿瘤患者的诊断和预后指标。