Assessment of response to induction therapy and its influence on 5-year failure-free survival in group III rhabdomyosarcoma: the Intergroup Rhabdomyosarcoma Study-IV experience--a report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group.
OBJECTIVE
Initial response to induction chemotherapy predicts failure-free survival (FFS) in osteosarcoma and Ewing's sarcoma. For Intergroup Rhabdomyosarcoma Study (IRS) IV patients with group III rhabdomyosarcoma, we assessed whether reported response assessed by anatomic imaging at week 8 predicted FFS.


METHODS
We studied 444 group III patients who received induction therapy, had response assessed at week 8 by anatomic imaging, and continued with protocol therapy. Induction chemotherapy was generally followed by radiation therapy (RT) starting after week 9. Response to induction therapy was determined at weeks 0 and 8. Local institutions coded response.


RESULTS
Response rate for the entire cohort at week 8 was 77% (95% CI, 73% to 81%; complete response [CR], 21%; partial response [PR], 56%) but response had no influence on FFS (P = .57). Two hundred seventy-two patients received standard-timing RT at week 9 and thus only chemotherapy during induction. Response rate was 81% (95% CI, 76% to 86%; CR, 22%; PR, 59%). In these patients, response did not influence FFS except for those with alveolar histology. One hundred thirty-two other patients received chemotherapy and RT during induction (up-front RT). Response rate was 65% (95% CI, 57% to 73%; CR, 12%; PR, 53%), but response had no influence on FFS (P = .69). Forty patients received no RT at all (protocol violation) and response to induction therapy had no effect on FFS.


CONCLUSIONS
In IRS-IV, response rate to induction therapy was 77% in group III patients, was independent of histology, and had no influence on FFS overall.
Burke
Megan
M
Children's Hospital Cleveland Clinic, Cleveland, USA.
Anderson
James R
JR
Kao
Simon C
SC
Rodeberg
David
D
Qualman
Stephen J
SJ
Wolden
Suzanne L
SL
Meyer
William H
WH
Breitfeld
Philip P
PP
D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D020360:Neoadjuvant Therapy; D012208:Rhabdomyosarcoma / Q000188:drug therapy* / Q000532:radiotherapy; D012983:Soft Tissue Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy; D016019:Survival Analysis