Radiation therapy for favorable histology Wilms tumor: prevention of flank recurrence did not improve survival on National Wilms Tumor Studies 3 and 4.
OBJECTIVE
To determine whether radiation therapy (RT) of patients with Wilms tumor of favorable histology prevented flank recurrence and thereby improved the survival outcomes.


METHODS
Recurrence and mortality risks were compared among groups of patients with Stage I-IV/favorable histology Wilms tumor enrolled in the third (n = 1,640) and fourth (n = 2,066) National Wilms Tumor Study Group studies.


RESULTS
Proportions of patients with flank recurrence were 0 of 513 = 0.0% for 20 Gy, 12 of 805 = 1.5% for 10 Gy, and 44 of 2,388 = 1.8% for no flank RT (p trend = 0.001 adjusted for stage and doxorubicin); for intra-abdominal (including flank) recurrence they were 5 of 513 = 1.0%, 30 of 805 = 3.7%, and 58 of 2,388 = 2.4%, respectively (p trend = 0.02 adjusted). Survival percentages at 8 years after intra-abdominal recurrence were 0 of 5 = 0% for 20 Gy, 10 of 30 = 33% for 10 Gy, and 34 of 58 = 56% for no RT (p trend = 0.0001). NWTS-4 discontinued use of 20 Gy RT, and the 8-year flank recurrence risk increased to 2.1% from 1.0% on NWTS-3 (p = 0.013). However, event-free survival was unaltered (88% vs. 86%, p = 0.39), and overall survival was better (93.8% vs. 90.8%, p = 0.036) on NWTS-4.


CONCLUSIONS
Partly because of lower postrecurrence mortality among nonirradiated patients, prevention of flank recurrence by RT did not improve survival. It is important to evaluate entire treatment policies with regard to long-term outcomes.
Breslow
Norman E
NE
Department of Biostatistics, University of Washington, Seattle, WA 98195-7232, USA.
Beckwith
J Bruce
JB
Haase
Gerald M
GM
Kalapurakal
John A
JA
Ritchey
Michael L
ML
Shamberger
Robert C
RC
Thomas
Patrick R M
PR
D'Angio
Giulio J
GJ
Green
Daniel M
DM
D000293:Adolescent; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D002648:Child; D004317:Doxorubicin / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000401:mortality / Q000473:pathology / Q000517:prevention & control / Q000532:radiotherapy*; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000517:prevention & control*; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D018335:Rhabdoid Tumor; D012306:Risk; D018227:Sarcoma, Clear Cell; D009396:Wilms Tumor / Q000401:mortality / Q000473:pathology / Q000517:prevention & control / Q000532:radiotherapy*
D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin