65. Functional Diagnosis of Cancer Using PET

Kyosan Yoshikawa, Katsumi Tamura, Takashi Tomemori, Noriyo Matsuno, Masahisa Koga, Susumu Kandatsu, Tetsuya Suhara, Kazutoshi Suzuki, Hirotoshi Kato, Junetsu Mizoe, Osamu Inoue, Fumio Shishido, Hiroshi Fukuda and Hirohiko Tsujii

Keywords: Positron emission tomography (PET), C-11 methionine, head and neck cancer, hepatocellular carcinoma, breast tumor

Positron emission tomography (PET) can demonstrate increased metabolic demand as visual images, and it provides alternative information for diagnosis that can be used to complement morphological observations. This year, we carried out three studies on (1) the usefulness of methionine PET for evaluation of the therapeutic effect and prognosis in head and neck cancer, (2) the imaging ability of FDG-PET for hepatocellular carcinoma, and (3) the imaging ability of methionine PET for breast tumor. In study (1), 22 cases with head and neck cancer were followed long term (70.3 months maximum) after HIMAC therapy. Kaplan-Maier methods were applied for evaluation of the relation between methionine uptake in the tumor and patient survival rate, and of the relation between the changing rate of tumor methionine uptake and tumor local control rate. Tumor methionine high uptake state before HIMAC therapy seemed to suggest tumor malignancy and high risk of occurring metastasis, i.e. prognosis poor. When tumor uptake decreased a lot after HIMAC therapy, it suggested good tumor local control. In study (2), 38 cases with hepatocellular carcinoma were studied by FDG-PET. We found that when the liver function was more damaged, liver tissue showed higher FDG accumulation. There was no relationship between tumor differentiation level and FDG uptake, and between the change of FDG uptake after HIMAC therapy and the reduction rate of tumor size. Cases that showed high reduction of tumor FDG uptake after HIMAC therapy tended to show reduced AFP level. In study (3), 9 cases with breast tumor were studied by methionine PET. All breast carcinoma showed positive accumulation of methionine. There was no relationship between methionine uptake level and FDG uptake level. We think that methionine PET gives different information about breast tumor, about differentiation between benignancy and malignancy, and about prognosis after treatment etc., in comparison with FDG-PET.