The role of technetium-99m methoxyisobutyl isonitrile scintigraphy in predicting the therapeutic effect of chemotherapy against nasopharyngeal carcinoma.

BACKGROUND The authors prospectively evaluated the correlation between technetium-99m methoxyisobutyl isonitrile ((99m) Tc-MIBI) accumulation in tumors and response to induction chemotherapy in patients with nasopharyngeal carcinoma (NPC). METHODS Eighty-six patients with locally advanced NPC underwent single-photon emission computed tomography 15 minutes after an intravenous injection of 740 megabecquerels (20 mCi) (99m) Tc-MIBI before chemotherapy. The tumor uptake ratio (TUR) was calculated. Two weeks after the second cycle of combined chemotherapy with 5-fluorouracil (5-FU) and cisplatin (DDP), the tumor response rate was evaluated. The correlation between (99m) Tc-MIBI accumulation in tumors and response to chemotherapy with 5-FU/DDP was examined. RESULTS Positive accumulation of (99m) Tc-MIBI in tumors was observed in 76 patients (88.4%). The tumor response was a complete response (CR) in 8 patients, a partial response (PR) in 68 patients, stable disease (SD) in 9 patients, and progressive disease (PD) in 1 patient. The response rate (CR and PR) to 5-FU/DDP chemotherapy in patients who had positive (99m) Tc-MIBI accumulation (tumor uptake ratio [TUR] >1.1) was higher than that in patients who had negative (99m) Tc-MIBI accumulation (TUR ≤ 1.1; 98.7% vs 10%; P < .001). CONCLUSIONS Patients with negative (99m) Tc-MIBI accumulation were resistant to 5-FU/DDP chemotherapy. (99m) Tc-MIBI imaging in patients with NPC was capable of predicting tumor response to chemotherapy with 5-FU/DDP and can help in the selection of patients for induction chemotherapy.