Use of 18F-FDG-PET-CT for Assessment of Response to Neoadjuvant Chemotherapy in Children With Wilms Tumor.
OBJECTIVE
The aim of this study was to evaluate the predictive value of fluorine-18-fluorodeoxyglucose positron emission tomography with computed tomography (F-FDG-PET-CT) in the assessment of histologic response to neoadjuvant chemotherapy in children with Wilms tumors (WTs).


METHODS
We prospectively registered 12 patients with WTs who were treated with 2 cycles of neoadjuvant chemotherapy and surgery. All patients underwent sequential F-FDG-PET-CT before (PET-CT1) and after (PET-CT2) neoadjuvant chemotherapy. Maximum standardized uptake value (SUVmax) was measured on PET-CT1 (SUV1) and PET-CT2 (SUV2). The percentage change in SUVmax (SUVmax reduction) was calculated. After surgery the effects of neoadjuvant chemotherapy were graded histopathologically: ≥90% necrosis indicated a good response and <90% necrosis was considered a poor response. The correlation between SUVmax reduction and histologic response was estimated using the Spearman correlation coefficient.


RESULTS
Among the 12 patients who underwent PET-CT before and after chemotherapy, SUVmax reduction was significantly different between the good response group and the poor response group (P=0.035). A significant, in terms of P value, correlation was found between pathologic response and SUVmax reduction (r=0.700; 95% confidence interval, 0.060-0.935; P=0.011). A threshold of 66% reduction in SUVmax was identified, with which partition, there were 8 good histologic responders (≥66% decrease in SUVmax) and 4 poor responders. The histologic complete response rate of the good responders was 87.5%, whereas that of poor responders was 0%. SUV1≥7 and SUV2≥2.4 were both considered to be with high risk of recurrence. In patients with SUV1≥7, 4/5 cases relapsed and 4/6 patients with SUV2≥2.4 relapsed.


CONCLUSIONS
As there seems to be a good correlation of changes in SUVmax and histologic response, PET-CT has the potential of predicting the response to neoadjuvant chemotherapy in children with WT. SUV1 and SUV2 by themselves might be a good prognosticator of the clinical outcome of WT pediatric patients treated with International Society of Pediatric Oncology protocols, although the reduction rate of SUVmax is much less powerful for prognosis.
Departments of *Pediatric Surgery †Nuclear Medicine, Xin Hua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
Zhen
Z
Qin
Yiyun
Y
Tang
Hui
H
Wang
Wei
W
Cai
Hongliang
H
Fu
Jianing
J
Li
Chao
C
Ma
D000970:Antineoplastic Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007223:Infant; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D008297:Male; D064847:Multimodal Imaging; D020360:Neoadjuvant Therapy; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D009396:Wilms Tumor / Q000000981:diagnostic imaging* / Q000188:drug therapy*
D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18