[(11)C]methionine positron emission tomography and survival in patients with bone and soft tissue sarcomas treated by carbon ion radiotherapy.
OBJECTIVE
The development of the novel carbon ion radiotherapy (CIRT) in the treatment of refractory cancers has resulted in the need for a way to accurately evaluate patient prognosis. We evaluated whether L-[methyl-(11)C]-methionine (MET) uptake and its change after CIRT were the early survival predictors in patients with unresectable bone and soft tissue sarcomas.


METHODS
MET positron emission tomography was prospectively performed in 62 patients with unresectable bone and soft tissue sarcomas before and within 1 month after CIRT. Tumor MET uptake was measured with the semiquantitative tumor:nontumor ratio (T/N ratio). The MET uptake in the tumor and relevant clinical parameters were entered into univariate and multivariate survival analysis.


RESULTS
The overall median survival time was 20 months. Patients with a baseline T/N ratio of <or=6 had a significant better survival than patients with a baseline T/N ratio >6 (2-year survival rate: 69.4% versus 32.3%; P = 0.01). Patients with a post-CIRT ratio of <or=4.4 had a better survival than that with a post-CIRT ratio >4.4 (2-year survival rate: 63.7% versus 41.3%; P = 0.01). A significant higher survival rate was observed in patients with post-therapeutic MET uptake change of >30% than patients in lower change group (2-year survival rate: 74.6% versus 41.6%; P = 0.049). The multivariate analysis showed that both baseline and post-CIRT T/N ratio were statistically significant independent predictors of patient survival. Tumors with larger T/N ratio had a significantly poorer prognosis.


CONCLUSIONS
MET uptake as measured by either baseline or post-CIRT T/N ratio was an independent predictor of survival in patients with bone and soft tissue sarcomas treated by carbon ion radiotherapy, whereas post-therapeutic MET uptake change might have potential value for the same purpose.
Zhang
Hong
H
Department of Medical Imaging, National Institute of Radiological Sciences, Chiba, Japan.
Yoshikawa
Kyosan
K
Tamura
Katsumi
K
Tomemori
Takashi
T
Sagou
Kenji
K
Tian
Mei
M
Kandatsu
Susumu
S
Kamada
Tadashi
T
Tsuji
Hiroshi
H
Suhara
Tetsuya
T
Suzuki
Kazutoshi
K
Tanada
Shuji
S
Tsujii
Hirohiko
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001692:Biological Transport; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000532:radiotherapy; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D008715:Methionine / Q000493:pharmacokinetics; D008875:Middle Aged; D015999:Multivariate Analysis; D011878:Radiotherapy / Q000379:methods; D012509:Sarcoma / Q000000981:diagnostic imaging* / Q000401:mortality / Q000532:radiotherapy; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000532:radiotherapy; D016019:Survival Analysis; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D008715:Methionine