Midcourse Thallium-201 Scintigraphy to Predict Tumor Response in Bone and Soft-Tissue Tumors

The purpose of this study was to assess the predictive power of 2O1@fl scintigraphy in the midcourse of chemotherapy for the final tumor response to chemotherapy in malignant bone and soft-tissue tumors. Methods: The 21 patients studied with 201fl scintigraphy were 14 males and 7 females (average age 39.8 ± 22.1 yr age range 8—74 yr).Planar scintigraphy was performed 15 mmafter injectionof 111 MBq 201@fl before chemotherapy, after the third chemotherapy cycle (midcourse) in all 21 patients and after the finalchemotherapy cycle but before surgery in 11 patients. The 201fl uptake ratio was calculated by dividingthe count density of the lesion by that of the contralateral normal area. The percent reduction of the 201@fl uptake ratio calculated by 100 x [(prechemotherapy ratio —postchemo therapy ratio)/prechemotherapy ratio] in the midcourse was corn pared with that after the final course of chemotherapy, and it also was compared with the histologic response. Results: In patients with histologicallycomplete response [(CR),n = 6] and with partial response [(PR),n = 5], the percent reduction in 2o1@fl uptake ratio after three cycles of chemotherapy was 64.1% ± 14.4% and 50.9% ±10.5%, respectively. In patients with histologically no change [(NC),n = 10], the percent reduction was 0.40% ± 18.2% after the third cycle; —5.3%±20.9% in four patients with full courses of chemotherapy (p < 0.0001 and p < 0.005 compared with the CR and PR groups, respectively). Afterthe finalcycle of chemotherapy, the percent reduction in 2o1@fl uptake ratio was 68.6% ±14.7%, 56.2% ± 6.1% and —0.3%± 172% in the CR, PR and NCgroups, respectively (NCversus CR, p < 0.0005; NCversus PR, p < 0.005). Conclusion: Thallium-201scintigraphyperformedinthe midcourse of chemotherapy is predictive ofthe finalresponse to chemotherapy thatcanbe demonstrated histologically. Serial2o1@fl scintigraphy in the midcourse of chemotherapy is useful in assessing final chemo therapeutic response in the early stage of chemotherapy, and it helps clinicians when choosing the most appropriate treatment strategies in patients with bone and soft-tissue tumors.