Incidence of biopsy-proven bone tumors in children: a report based on the Dutch pathology registration "PALGA"

Reduced human leukocyte antigen expression in advanced-stage Ewing sarcoma: implications for immune recognition

Ewing sarcoma (EWS) is a tumour most commonly arising in bone, although on occasion in soft tissue, with a poor prognosis in patients with refractory or relapsed disease, despite multimodal therapy. Immunotherapeutic strategies based on tumour-reactive T and/or natural killer cells may improve the treatment of advanced-stage EWS. Since cellular immune recognition critically depends on human leukocyte antigen (HLA) expression, knowledge about HLA expression in EWS is crucial in the design of cellular immunotherapeutic strategies. Constitutive and IFNgamma-induced HLA class I expression was analysed in EWS cell lines (n = 6) by flow cytometry, using antibodies against both monomorphic and allele-specific antigens. Expression of antigen processing pathway components and beta-2 microglobulin (beta2m) was assessed by western blot. Expression of class II transactivator (CIITA), and its contribution to HLA class II expression, was evaluated by qRT-PCR, transduction assays, and flow cytometry. beta2m/HLA class I and class II expression was validated in EWS tumours (n = 67) by immunofluorescence. Complete or partial absence of HLA class I expression was observed in 79% of EWS tumours. Lung metastases consistently lacked HLA class I and sequential tumours demonstrated a tendency towards decreased expression upon disease progression. Together with absent or low constitutive expression levels of specific HLA class I loci and alleles, and differential induction of identical alleles by IFNgamma in different cell lines, these results may reflect the existence of an immune escape mechanism. Inducible expression of TAP-1/-2, tapasin, LMP-2/-7, and the beta2m/HLA class I complex by IFNgamma suggests that regulatory mechanisms are mainly responsible for heterogeneity in constitutive class I expression. EWSs lack IFNgamma-inducible HLA class II, due to lack of functional CIITA. The majority of EWS tumours, particularly if advanced-stage, exhibit complete or partial absence of both classes of HLA. This knowledge will be instrumental in the design of cellular immunotherapeutic strategies for advanced-stage EWS.

Extra-osseous Ewing sarcoma

BACKGROUND

Clinical data and data on outcome of extra-osseous Ewing tumors are scarce.

PROCEDURE

After a search for Ewing tumors in the database of a single institution over a period of 20 years, 16 out of 192 cases were found to have extra-osseous primary tumors.

RESULTS

Ages at initial diagnosis ranged from 2.5 to 17 years. Follow-up period ranged from 4 months to 24.8 years (mean 8.4 years). Eleven patients were treated according to protocols for Ewing tumors, while in 4 cases soft tissue protocols were used. In a single patient only surgery was done. Two patients had progressive disease despite chemotherapy; a third patient had only tumor response on the initial 2 chemotherapy courses. All 3 patients with initially metastatic disease died. One patient developed a second malignancy. Overall survival at 5 years was 75%. Event-free survival (EFS) at 5 years was 68%; for nonmetastatic patients 5-year EFS was 83%.

CONCLUSION

The authors conclude that nonmetastasized extra-osseous Ewing tumors have a prognosis at least similar to that of osseous Ewing tumors.

Recurrence of Ewing sarcomas of the chest wall

BACKGROUND

Ewing sarcomas (ES) of the chest wall are rare. Local recurrences occur in approximately 20% of these patients; however literature on this topic is scarce. Our aim was to analyze the influence of the extent of surgical resection on outcome, and to find positive prognostic factors for survival.

PROCEDURE

A retrospective analysis of all patients who were under 18 and treated between 1977 and 2006 for Ewing sarcoma of the chest wall was performed.

RESULTS

Twenty-seven patients with ES were diagnosed at our institution; 14 males and 13 females. Twenty-three patients underwent local resection, which was complete in 13. Nine patients had a wide resection, including more ribs than just the affected one. Complete remission (CR) was achieved in 14/27 patients. Recurrence was observed in 13 patients: local recurrence (LR) and distant metastasis (DM) both in 7. One of the patients had both LR and DM. All patients with LR and two patients with DM only died of disease. Overall survival after 10 and 20 years was 73% and 47%, respectively. Complete resection, wide resection, gender, or age were no significant factors affecting outcome.

CONCLUSIONS

Relapse carries a high mortality risk and none of the patients with LR eventually survived. Wide resection of at least a complete normal adjacent rib above and below the thoracic wall tumor as a fixed rule seems unnecessary.