Does the time-point of relapse influence outcome in pediatric rhabdomyosarcomas?

Childhood rhabdomyosarcoma (RMS), a soft tissue malignant tumor of skeletal muscle origin, accounts for approximately 3.5% of the cases of cancer among children 0-14 years and 2% of the cases among adolescents and young adults 15-19 years of age.

We evaluated survival (SUR) after first relapse depending on the time to relapse (TTR) in RMSs of childhood and adolescence. Early, intermediate, and late relapsing patients were evaluated for prognostic risk factors.

Two hundred thirty-four patients with RMS enrolled in the German sarcoma trial CWS-81, CWS-86, CWS-91, and CWS-96 met selection criteria. Of the 234 patients, 35%, 32%, and 33% relapsed within 6 (early), 6-12 (intermediate), and more than 12 (late) months respectively after the end of primary therapy. Four-year SUR was 12%, 21%, and 41% for early, intermediate, and late relapse respectively (P < 0.001). Four-year SUR after local relapse was 18% (early), 38% (intermediate), and 49% (late). Embryonal RMS showed four year SUR of 16%, 30%, and 46% (P < 0.001) whereas alveolar histology showed four year SUR of 8%, 6%, and 23% (P < 0.01) for early, intermediate, and late relapse respectively.

TTR has significant influence on prognosis in relapsed RMS. It influences SUR independent of other features such as type of relapse, histology, tumor site, primary treatment time or irradiation in primary treatment.