Potential role of PET-CT in chemotherapy efficacy assessment and recurrence diagnosis in a patient with a Wilms' tumour

BACKGROUND: Wilms' tumour is the most frequent renal malignancy in children. There is no worldwide consensus regarding treatment and PET-CT role in this neoplasm. The aim of this report is to demonstrate the potential role of PET-CT in chemotherapy efficacy assessment and recurrence diagnosis. CASE description: a 7-year-old boy was diagnosed with blastemic type Wilms' tumour and underwent neoadjuvant chemotherapy, nephrectomy, and adjuvant chemotherapy in compliance with SIOP protocol. Three years later the patient underwent surgical resection of the metastasis and chemoradiotherapy. Nine months later tomography and PET-CT were performed (during the third month of the treatment due to a second recurrence). The results were equivocal but within four months the boy underwent surgical resection of a third recurrence. Fourteen months later a second PET-CT revealed an active disease with extensive involvement of the left lung and pleura. The patient was referred to oral palliative chemotherapy. DISCUSSION: Equivocal PET-CT results during chemotherapy should be interpreted with caution. The first, during third line chemotherapy, was equivocal; however, an early massive recurrence three months later indicates that treatment was ineffective. The second PET-CT examination fourteen months later, as the only modality, depicted massive progression of the disease. This suggests the value of this examination in recurrence diagnosis. CONCLUSIONS: PET-CT seems to be valuable technique in recurrence detection in patients with histologically unfavourable tumours. Equivocal results of PET-CT should raise suspicion of recurrence even in recently treated patients. The timing of CIM and PET-CT should be considered individually - no universal and reliable schedule exists.