Assessment of the effectiveness of cancer therapy using PET.

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Morphologiacal imaging strategies such as plain radiography, X-ray CT,MRI and ultrasonography have been used for the evaluation of cancer treatment. The shape and diameter of tumor are compared before and after the treatment. Occasionally, we meet the cases of residual mass without viable tumor cells after the therapy. And there are many cases of early recurrent disease even if we could not identify the residual mass just after the treatment. Morphological approach has limited ability in the assessment of cancer therapy.FDG-PET has been accepted as a useful diagnostic tool in oncology. We applied FDG-PET study to the assessment of cancer treatment and compared with the morphological methods. Three consecutive FDG-PET studies before, in the middle of and after the radiation therapy were performed in fifteen patients with non-small cell lung carcinomas. FDG accumulation to the tumors were compared in three scans of each patient. Reduction of tumor size measured by plain radiography or CT … More after the treatment was correlated to FDG accumulation in most of the patients. However, there were some patients without agreement between morphological study and FDG-PET.These results suggest that FDG-PET has different information on the number of tumor cells and metabolic activity.Cellularity of the tumor and partial volume effect were studied, as a basic study of FDG uptake to tumor. Thirty-seven patients with suspected recurrent disease of rectal cancer were studied with FDG-PET.Correlation between the size of tumors and the FDG uptake was studied. FDG accumulation was compared to cellularity observed in histopathological examinations in several subjects. Positive correlation was found between the size and the uptake. This suggests that the size of the tumor should be taken into consideration for accurate estimation of FDG uptake. There was a correlation between cellularity and FDG uptake. When FDG-PET is used for the evaluation of therapy, the accumulation of FDG is considered to be dependent on the number of residual tumor cells.FDG-PET is able to provide new information, which could not be obtained by conventional morphological diagnostic imaging technique. FDG-PET is aeffective method for the assessment of cancer therapy. Less