Prediction of chemotherapy response in untreated malignant lymphomas using technetium-99m methoxyisobutylisonitrile scan: comparison with P-glycoprotein expression and other prognostic factors. A preliminary peport.

BACKGROUND: The purpose of this study was to predict chemotherapy response in untreated malignant lymphomas using technetium-99m methoxyisobutylisonitrile (Tc-MIBI) scan. METHODS: Twenty-five patients with malignant lymphoma were studied before receiving chemotherapy. Early Tc-MIBI scan was performed 10 min after intravenous injection of Tc-MIBI. Immunohistochemical analyses were performed on multiple non-consecutive sections of the biopsy specimens to determine Pgp expression. Chemotherapy response was evaluated in the first 1-2 years after completion of treatment by clinical and radiological methods. RESULTS: The mean tumor-to-background ratio of the 15 patients with good response (3.3 +/- 0.6) was significantly higher than that of the 10 patients with poor response (1.2 +/- 0.1). Among the 15 patients with good response to chemotherapy, all had positive Tc-MIBI scan results but negative Pgp expression. Among the 10 patients who had poor response to chemotherapy, all 10 had negative Tc-MIBI scan, but six patients had positive Pgp expression and four had negative Pgp expression. Significant differences were found in the incidences of good and poor responses determined by Tc-MIBI scan and Pgp expression. However, there were no significant differences in the incidences of good and poor responses for other prognostic factors. CONCLUSION: Compared with other prognostic factors, early Tc-MIBI scan more accurately predicts chemotherapy response in patients with malignant lymphoma.