Localised Ewing sarcoma/PNET of bone--prognostic factors and international data comparison.

To determine if the distribution of prognostic factors accounted for the differences when the outcome for localised Ewing Sarcoma/PNET bone in Saudi Arabia was compared with results from countries with well developed health care systems. Retrospective analysis was undertaken of 163 consecutive patients of all ages, treated with radical intent at KFSHRC from 1975 to 1998. Standard chemotherapy was commenced in all patients. The local treatment modality was resection +/- radiation in 30% and radiation treatment alone in 67%. Size data were available for 51 patients treated from 1994 to 1998, inclusive. One third of these patients had tumors with volume >500 ml. Three year survival significantly increased with the year of diagnosis, 1975-1988 45%; 1989-1993 55%; and 1993-1998 63% (P = 0.006). Favorable prognostic factors were age < or =14 (P = 0.07); site, distal extremity, and skull (P = 0.08); and volume < or = 200 ml (P = 0.06). Secondary prognostic factors were response to induction chemotherapy, both histological, 100% necrosis, (P = 0.04) and clinical CR+PR, (P = 0.02). From 1994 to 1998, 3 year survival for tumors in the distal extremity and skull was 80% and for small tumors, < 200 ml, at any site was 82%. In comparison, the 3 year survival for patients with tumors at any other sites was 60%, and for tumors >200 ml, 55%. Overall survival progressively improved. From 1994 to 1998 the survival of patients with small tumors and/or favorable sites was similar to the best reported results. It was not possible to compare results by tumor size for large tumors, > 500 ml, due to the absence of data from elsewhere. A better staging system is required for the international comparison of results.