Koizumi Mitsuru, Saga Tsuneo, Yoshikawa Kyosan, Suzuki Kazutoshi, Yamada Shigeru, Hasebe Mitsuhiko, Ohashi Seiya, Abd-Elrazek Sherif, Ishikawa Hiroyuki, Sagou Kenji, Tamura Katsumi, Hara Ryusuke, Kato Hirotoshi, Yasuda Shigeo, Yanagi Takeshi, Tsujii Hirohiko
Diagnostic Imaging, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inageku, Chiba, Japan.
Mol Imaging Biol. 2008 Nov-Dec;10(6):374-80. doi: 10.1007/s11307-008-0156-1. Epub 2008 Aug 5.
Progress of the novel carbon ion radiotherapy (CIRT) in the treatment of cancers has created the need for a method to accurately evaluate the response. We investigated whether L-[11C]methyl-methionine (11C-methionine) uptake at pre- and post-CIRT could be an early response predictor in patients with pelvic recurrence of rectal cancer.
11C-Methionine-positron emission tomography (PET) was performed prospectively in 53 patients with pelvic recurrence of rectal cancer before CIRT, and 48 patients were performed 11C-methionine PET at 1 month after CIRT. 11C-Methionine tumor uptake was measured by the tumor to muscle ratio (T/M ratio). The T/M ratios were evaluated in relation to clinical outcomes such as local re-recurrence, distant metastasis, and survival. The response to CIRT was also judged by computed tomography (CT) and magnetic resonance imaging (MRI). 11C-Methionine PET judgment was compared with CT/MRI judgment regarding the relevance to clinical outcome.
Baseline T/M ratio was 5.27+/-1.90 (mean+/-SD) in patients without developing local re-recurrence and 7.66+/-3.17 in patients with local re-recurrence (p=0.023, Mann-Whitney U test). Post-CIRT T/M ratios were 3.10+/-1.28 in patients without local re-recurrence and 6.15+/-2.98 in patients with local re-recurrence (p=0.006, Mann-Whitney U test). By Kaplan-Meier analysis with log-rank test, patients with a baseline T/M ratio of <or=7.6 or a post-CIRT T/M ratio of <or=5.0 had significant lower pelvic re-recurrence rate. However, the percent change (reduction rate) from baseline to post-CIRT T/M ratio did not have significant relation to pelvic re-recurrence. There were no significant differences between 11C-methionine results (baseline T/M ratio, post-CIRT T/M ratio and percent change) and other clinical parameters (distant metastasis and survival).
11C-methionine-PET can be used for early prediction of local re-recurrence after CIRT. Because CIRT is local therapy, (11)C-methionine-PET cannot predict distant metastasis or survival after CIRT.
新型碳离子放射治疗（CIRT）在癌症治疗方面的进展使得需要一种准确评估反应的方法。我们研究了直肠癌盆腔复发患者在CIRT前后L-[¹¹C]甲基蛋氨酸（¹¹C-蛋氨酸）摄取是否可作为早期反应预测指标。
对53例直肠癌盆腔复发患者在CIRT前进行前瞻性¹¹C-蛋氨酸正电子发射断层扫描（PET），48例患者在CIRT后1个月进行¹¹C-蛋氨酸PET检查。通过肿瘤与肌肉比值（T/M比值）测量¹¹C-蛋氨酸肿瘤摄取情况。根据局部再复发、远处转移和生存等临床结果评估T/M比值。还通过计算机断层扫描（CT）和磁共振成像（MRI）判断对CIRT的反应。将¹¹C-蛋氨酸PET判断结果与CT/MRI判断结果在与临床结果的相关性方面进行比较。
未发生局部再复发患者的基线T/M比值为5.27±1.90（均值±标准差），发生局部再复发患者的基线T/M比值为7.66±3.17（p = 0.023，曼-惠特尼U检验）。CIRT后，未发生局部再复发患者的T/M比值为3.10±1.28，发生局部再复发患者的T/M比值为6.15±2.98（p = 0.006，曼-惠特尼U检验）。通过带有对数秩检验的Kaplan-Meier分析，基线T/M比值≤7.6或CIRT后T/M比值≤5.0的患者盆腔再复发率显著较低。然而，从基线到CIRT后T/M比值的百分比变化（降低率）与盆腔再复发无显著相关性。¹¹C-蛋氨酸结果（基线T/M比值、CIRT后T/M比值和百分比变化）与其他临床参数（远处转移和生存）之间无显著差异。
¹¹C-蛋氨酸PET可用于CIRT后局部再复发的早期预测。由于CIRT是局部治疗，¹¹C-蛋氨酸PET无法预测CIRT后的远处转移或生存情况。
