Impact of Two Measures of Micrometastatic Disease on Clinical Outcomes in Patients with Newly Diagnosed Ewing Sarcoma: A Report from the Children's Oncology Group

Abstract

Purpose Flow cytometry and RT-PCR can detect occult Ewing sarcoma (ES) cells in the blood and bone marrow (BM). These techniques were used to evaluate the prognostic significance of micrometastatic disease in ES. Experimental Design Newly diagnosed patients with ES were enrolled on two prospective multi-center studies. In the flow cytometry cohort, patients were defined as “positive” for BM micrometastatic disease if their CD99+/CD45− values were above the upper limit in 22 control patients. In the PCR cohort, RT-PCR on blood or BM samples classified the patients as “positive” or “negative” for EWSR1/FLI1 translocations. The association between micrometastatic disease burden with clinical features and outcome was assessed. Co-expression of IGF-1R on detected tumor cells was performed in a subset of flow cytometry samples. Results The median total BM CD99+CD45− percent was 0.0012% (range 0–1.10%) in the flow cytometry cohort, with 14/109 (12.8%) of ES patients defined as “positive.” In the PCR cohort, 19.6% (44/225) patients were “positive” for any EWSR1/FLI1 translocation in blood or BM. There were no differences in baseline clinical features or event-free or overall survival between patients classified as “positive” vs. “negative” by either method. CD99+CD45− cells had significantly higher IGF-1R expression compared to CD45+ hematopoietic cells (mean geometric mean fluorescence intensity 982.7 vs. 190.9; p<0.001). Conclusion The detection of micrometastatic disease at initial diagnosis by flow cytometry or RT-PCR is not associated with outcome in newly diagnosed patients with ES. Flow cytometry provides a tool to characterize occult micrometastatic tumor cells for proteins of interest.

Detection of circulating tumour DNA is associated with inferior outcomes in Ewing sarcoma and osteosarcoma: a report from the Children’s Oncology Group

“…Prior studies have evaluated the prognostic impact of fusion transcript detection in the peripheral blood or bone marrow using reverse transcription-polymerase chain reaction, yet have not shown consistent prognostic value. 8,9 Likewise, measures of Ewing sarcoma tumour cells in the peripheral blood and bone marrow by flow cytometry were not prognostic. 9–11 A range of circulating biomarkers have been evaluated in osteosarcoma, though none yet validated.…”

Bone marrow biopsy in the initial staging of Ewing sarcoma: Experience from a single institution

“…Our data show that the probability of understaging patients with no evidence of metastases with the modern imaging techniques available today is very low. Schleiermacher et al in 2003 reported a correlation between detection of ES translocation by RT‐PCR in morphologically negative bone marrow samples with relapse and death, but a more recent study did not confirm these data . Other studies are needed on this topic, and the data presently available do not recommend the routine use of BMB in patients with localized ES.…”

Detection of circulating sarcoma tumor cells using a microfluidic chip-type cell sorter

“…The current study established a new protocol for CSC detection using a microfluidic chip-type cell sorter, the On-chip Sort. Several reports have described detection of CSCs using different devices, such as a size-exclusion microfiltration system 24 and flow cytometry 25,26 with specific markers. However, the utility of size-exclusion is limited by the lack of a histology-specific marker.…”