Prognostic value of Tc-99m-MIBI performed during middle course of preoperative chemotherapy in patients with malignant bone and soft-tissue tumors.

PURPOSE This study was aimed to determine whether Tc-99m-hexakis-2-methoxyisobutylisonitrile (MIBI) scintigraphy performed in the middle of preoperative chemotherapy has a prognostic value in patients with malignant bone and soft tissue tumors (MBST). MATERIALS AND METHODS In 90 patients with MBST, Tc-99m-MIBI scintigraphy was performed 15 minutes after tracer injection before the first and after the third chemotherapy cycles. After 5 cycles of chemotherapy and tumor resection, therapeutic effect was assessed by histopathology. The percent reduction of uptake ratio (ΔUR) was calculated according to the following equation: 100 × ([prechemotherapy UR - post-middle course of chemotherapy UR]/prechemotherapy UR). RESULTS The average follow-up for the entire population was 52 months. Twenty-one patients had clinically detectable metastases at initial presentation (primary metastasis). Kaplan-Meier analysis demonstrated that absence of metastasis was associated with good survival in all patients, in patients with bone tumor, and those with soft tissue tumor (P < 0.0001, P < 0.0001, and P = 0.0003, respectively), and ΔUR ≧30% was also associated with survival in all patients and patients with bone tumor (P = 0.011 and P = 0.047, respectively), but was marginal in those with soft tissue tumor (P = 0.091). Multivariate analysis showed that primary metastasis was the most powerful independent predictor of a lethal clinical outcome in all patients, in both patients with bone and soft tissue tumors (hazard ratio [HR]: 4.9, 95% confidence interval [CI]: 2.61-9.08, P < 0.0001; HR: 15.1, CI: 4.86-52.7, P < 0.0001; HR: 3.7, CI: 1.45-8.94, P = 0.0069, respectively) and showed that Tc-99m-MIBI scintigraphy had a good independent long-term prognostic value in all patients and patients with bone tumor (HR: 2.2, CI: 1.14-4.43, P = 0.017; HR: 6.0, CI: 2.01-21.6, P = 0.0009, respectively) but not in those with soft tissue tumor (HR: 1.5, CI: 0.61-4.09, P = 0.38). Good disease-free survival was associated with ΔUR ≧30% in all patients and patients with soft tissue tumor (P = 0.0093 and P = 0.017, respectively) but not in those with bone tumor (P = 0.19). CONCLUSIONS Tc-99m-MIBI scintigraphy at the middle course of preoperative chemotherapy could be used as a prognostic indicator in patients with MBST.