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Assessment of response to
induction therapy and its influence on 5-year failure-free survival (FFS) in
Group III rhabdomyosarcoma (RMS): Intergroup Rhabdomyosarcoma Study (IRS)-IV
experience
P. P. Breitfeld, J. Anderson, S. Kao, D. Rodeberg, S. Qualman, S. Wolden, W.
Meyer, Children's Oncology Group
Duke University Medical Center, Durham, NC; University of
Nebraska Medical Center, Omaha, NE; University of Iowa, Iowa City, IA; Mayo
Clinic, Rochester, MN; Childrens Hospital of Columbus, Columbus, OH; Memorial
Sloan Kettering, New York, NY; University of Oklahoma, Oklahoma City, OK
Background. Initial response to induction chemotherapy (CT)
predicts FFS in osteosarcoma and Ewing sarcoma.
Current European studies in RMS tailor therapy based on induction
response.
For IRS IV subjects with Group III RMS, we assessed whether reported
response to induction therapy predicted FFS.
Methods. We studied 453 Group III subjects who received induction
CT, had response assessed at week 8 and continued with protocol therapy.
Induction CT was followed by radiation therapy (RT) starting after week
9.
Response to induction therapy was determined by radiographic measurement
of tumor at weeks 0 and 8.
Complete response (CR: complete resolution of disease), partial response
(PR: ≥ 50% decrease in the sum of the products of the maximum
perpendicular diameters of measurable lesions), no response (NR: < 50%
decrease and < 25% increase), or progressive disease (>25% increase) was
coded by local institutions.
Results. Response rate at week 8 was 77% (CR=21%, PR=56%) but
response had no influence on FFS (p=0.89).
272 subjects received only CT during induction.
Response rate was 81% (CR=22%, PR=59%) and was independent of histology
and tumor size.
In these subjects, response did not influence FFS except for those with
alveolar histology.
141 other subjects received CT and RT during induction, usually because
of a parameningeal primary with intracranial extension.
Response rate was 65% (CR=12%, PR=53%) but response had no influence on
FFS.
40 subjects received no RT at all (protocol violation) and response to
induction CT had no effect on FFS.
Conclusion. In IRS IV, response rate to induction therapy was 77%
in Group III subjects but induction response had no influence on FFS
overall.
Table 1. Response rate and FFS by induction
therapy and histology
|
N
|
CR
|
PR
|
NR
|
p-value for FFS
|
|
|
Rate
|
FFS
|
Rate
|
FFS
|
Rate
|
FFS
|
|
|
All
|
453
|
21%
|
75%
|
56%
|
71%
|
23%
|
77%
|
0.89
|
|
Induction CT
|
272
|
22%
|
81%
|
59%
|
72%
|
19%
|
84%
|
0.34
|
|
Embryonal
|
185
|
21%
|
86%
|
60%
|
87%
|
19%
|
86%
|
0.96
|
|
Alveolar
|
86
|
24%
|
71%
|
57%
|
39%
|
19%
|
81%
|
0.03
|
|
Induction CT and RT
|
141
|
12%
|
76%
|
53%
|
67%
|
35%
|
73%
|
0.70
|
Copyright 2004 American Society of Clinical Oncology All rights
reserved worldwide.
Source: http://www.asco.org/ac/1,1003,_12-002636-00_18-0026-00_19-001205,00.asp
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