Background/purpose: Computed tomography (CT) of the chest with its increased sensitivity frequently identifies lesions not visible on chest radiograph. Treatment of such lesions is controversial. A recent review suggests that patients with Wilms' tumor with pulmonary lesions detected only by CT, who were treated with dactinomycin and vincristine, have an inferior outcome compared with those who also received pulmonary radiation therapy (RT) and doxorubicin. It is important to determine if these small lesions seen only on CT represent metastatic disease and whether patients with these lesions require RT and/or doxorubicin for optimal outcome.
Methods: Patients with Wilms' tumor with lung metastasis, registered on National Wilms' Tumor Study 5, were reviewed, and those with CT-only lesions who had a radiology and surgical checklist submitted were identified. The treatment regimens of these patients and the histological findings of the pulmonary lesions are presented. We analyzed the pathological findings by whether the patients had single or multiple lesions.
Results: Of 2498 patients registered on National Wilms' Tumor Study 5, 252 had pulmonary metastases. Of these patients, 129 (5.2%) had CT-only lesions (<1 cm). Forty-two of these patients (20 boys and 22 girls) underwent lung biopsy at the discretion of the attending physicians. The local tumor stages in these patients were stage I (7%), II (34%), and III (59%). The treatment stages in these patients were stage I (n = 3, 2 drugs), II (n = 3, 2 drugs), III (n = 12, 3 drugs); and IV (n = 24, 3 drugs + RT). There were 16 patients with isolated lung lesions and 26 with multiple lesions, average size 5.8 +/- 0.5 mm. Of 16 isolated lesions, 13 patients (82%) and 69% (18/26) with multiple lesions had tumor on biopsy. Of the 24 who received RT, 8 had a negative biopsy and, thus, may not have needed the RT. Five of 6 treated with just 2 drugs may have been undertreated. Nine of 12 treated with 3 drugs had tumor on biopsy.
Conclusions: Computed tomography-only pulmonary lesions are not invariably tumor, demonstrating the need for histopathological confirmation. Biopsy remains critical until radiographic techniques allow differentiation between benign and malignant lesions to optimally direct therapy.