45. Functional Diagnosis and Evaluation of Therapeutic Effects for Cancer using PET
Kyosan Yoshikawa, Katsumi Tamura, Yasunori Imai, Noriyo Matsuno Masahisa Koga, Masakuni Kanai, Susumu Kandatsu, Hirohiko Tsujii, Tetsuya Suhara, Katsuya Yoshida, Kazutoshi Suzuki, Osamu Inoue, Fumio Shishido and Hiroshi Fukuda
Keywords: positron emission tomography, heavy ion beam therapy, therapeutic effects
Positron emission tomography (PET) can demonstrate increased metabolic demand as visual images, and it provides alternative information for diagnosis which can be used to complement morphological observations. We have showed the usefulness of PET with 11C-methionine for the diagnosis of Nymph node metastases in patients with lung cancer. This time, we evaluated the relationship between the tendency for Nymph node metastases to appear after heavy ion beam therapy and 11C-methionine PET diagnosis before and/ or soon after heavy ion beam therapy in patients with lung cancer. We selected 53 patients, with stage I non-small cell lung cancer, which were observed more than 1 year after heavy ion beam therapy. Eleven patients in our cases showed Nymph node metastases after irradiation. Mean term from the end of irradiation to the final diagnosis of Nymph node metastases was seven months. Some cases showed somewhat or considerably high methionine accumulation by PET before and/ or soon after heavy ion beam therapy. PET diagnosis seemed to be useful for selecting patients who need strict follow up for Nymph node metastases. Precise follow up, early detection of Nymph node metastasis and adequate ther apy for the metastatic lesion seemed to improve prognosis of lung cancer patients.
We studied the usefulness of methionine PET for the evaluation of esophageal cancer. We checked mainly these three points: (1) how much methionine accumulates in non-treated esophageal cancer, (2) the role of PET in the evaluation of therapeutic ef feats, and (3) the relation between appearance of distant metastasis after therapy and methionine PET findings before treatment. Methionine PET tended to show high accumulation in non-treated esophageal cancer and mean TMR was 5.99 (from 1.93 to 11.7) When we evaluated the therapeutic effect using PET by change of methionine accumulation between preirradiation and postirradiation, it was important Cheat the tumor shows a high accumulation of methionine (more than 5.0 TMR) before irradiation. If TMR of esophageal cancer lesion was higher than 5.0 at pretreatment and TMR was reduced to less than 3.5 at post treatment, we could evaluate the benefit of the treatment. Cases which showed very high methionine accumulation at preirradiation, TMR > 8, showed high distant metastases late at 83%. Other cases, with intermediate or less methionine accumulation, showed low distant metasEases late at O%. We thought that the high level of methionine accumulation in esophageal cancer at pretreatment might indicate high risk of distant metastasis possibility.