Evaluation of Treatment Response & Recurrence in Childhood Solid Tumor with Thallium Scan

Lee, Sun Min; Lee, Kun Soo

Abstract

PURPOSE: During the follow-up period of the patient who was diagnosed as rhabdomyosarcoma and treated between 1991 and 1992 in Kyungpook National University Hospital (KNUH), the residual mass lesion on computerizing tomography (CT) was suspected as tumor progress. But, it was diagnosed as necrotic tissue by excisional biopsy and he has survived without recurrence until now. So, we have the necessity of the method that is able to differentiate the remnant tumor with necrotic tissue during or after treatment. The objective of this study was to evaluate prospectively the effectiveness of thallium (Tl-201) scan in detecting the bioavailability of tumor at diagnosis and after treatment.
METHODS
CT and/or magnetic resonance imaging (MRI) and Tl-201 scan at diagnosis, during the treatment and after treatment were conducted in 19 solid tumor patients treated for their diseases from December 1996 to June 1998, in Pediatric Department of KNUH. And we evaluated the recurrence of solid tumors following them up to March 2001.
RESULTS
In the cases of the presence of solid tumor in CT or MRI at diagnosis, we could also find them on Tl-201 scan in all of them. During the treatment, PNET patient had the mass lesion on MRI and Tl-201 scan, we kept going on the chemotherapy and radiotherapy. And retinoblastoma patient also had continued chemotherapy after confirming the mass lesion on MRI, not Tl-201 scan. Six cases (alveolar soft part sarcoma, medulloblastoma, Ewing sarcoma, Non-Hodgkin's lymphoma, rhabdomyosarcoma, neuroblastoma) in which no mass lesion were found in CT or MRI and Tl-201 scan had their final therapy. After finishing the treatment, high-grade anaplastic astrocytoma patient confirmed the mass lesion on MRI and Tl-201 scan and expired irrespective of retreatment after 19 months of diagnosis. In 2 cases of solid tumor on CT scan, not on Tl-201 scan, germ cell tumor patient has been followed up until now without recurrence with normal alpha-FP level, and NHL patient has survived without recurrence. Four cases (Non-Hodgkin's lymphoma; 2 cases, medulloblastoma; 1 case, ependymoma; 1 case) with negative finding on CT or MRI and Tl-201 scan also has survived without recurrence.
CONCLUSION
Although CT or MRI is used commonly in the follow-up period of childhood solid tumor, Tl-201 scan can be the useful method of differentiating viable tumor with necrotic tissue in the view of cost-effectiveness and availability.