Benefit of intensified therapy for patients with local or regional embryonal rhabdomyosarcoma: results from the Intergroup Rhabdomyosarcoma Study IV.
OBJECTIVE
To compare failure-free survival (FFS) and survival for patients with local or regional embryonal rhabdomyosarcoma treated on the Intergroup Rhabdomyosarcoma Study (IRS)-IV with that of comparable patients treated on IRS-III.


METHODS
Patients were retrospectively classified as low- or intermediate-risk. Low-risk patients were defined as those with primary tumors at favorable sites, completely resected or microscopic residual, or orbit/eyelid primaries with gross residual disease and tumors less than 5 cm at unfavorable sites but completely resected. Intermediate-risk patients were all other patients with local or regional tumors.


RESULTS
Three-year FFS improved from 72% on IRS-III to 78% on IRS-IV for patients with intermediate-risk embryonal rhabdomyosarcoma (P =.02). Subset analysis revealed two groups that benefited most from IRS-IV therapy. FFS at 3 years for patients with resectable node-positive or unresectable (group III) embryonal rhabdomyosarcoma arising at certain favorable sites (head and neck [not orbit/eyelid or parameningeal] and genitourinary [not bladder or prostate]) improved from 72% on IRS-III to 92% on IRS-IV (P =.01). Similarly, 3-year FFS for patients with completely resected tumor or with only microscopic disease remaining (group I or II) at unfavorable sites improved from 71% on IRS-III to 86% on IRS-IV (P =.04). Only patients with unresectable embryonal rhabdomyosarcoma (group III) at unfavorable sites had no improvement in outcome on IRS-IV (3-year FFS for IRS-III and IRS-IV, 72% and 75%, respectively; P =.31).


CONCLUSIONS
IRS-IV therapy benefited certain subgroups of patients with intermediate-risk embryonal rhabdomyosarcoma. A doubling of the intensity of cyclophosphamide (or ifosfamide equivalent) dosing per cycle between IRS-III and IRS-IV is thought to be a key contributing factor for this improvement.
Baker
K S
KS
Intergroup Rhabdomyosarcoma Study Group, Arcadia, CA 91066-6012, USA.
Anderson
J R
JR
Link
M P
MP
Grier
H E
HE
Qualman
S J
SJ
Maurer
H M
HM
Breneman
J C
JC
Wiener
E S
ES
Crist
W M
WM
D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003520:Cyclophosphamide / Q000008:administration & dosage; D003609:Dactinomycin / Q000008:administration & dosage; D018450:Disease Progression; D018572:Disease-Free Survival; D005047:Etoposide / Q000008:administration & dosage; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D007069:Ifosfamide / Q000008:administration & dosage; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D018233:Rhabdomyosarcoma, Embryonal / Q000188:drug therapy* / Q000473:pathology; D012307:Risk Factors; D014750:Vincristine / Q000008:administration & dosage
D003609:Dactinomycin; D014750:Vincristine; D005047:Etoposide; D003520:Cyclophosphamide; D007069:Ifosfamide