11C-Methionine-PET for Evaluation of Carbon Ion Radiotherapy in Patients with Pelvic Recurrence of Rectal Cancer

• Published in: Molecular imaging and biology 2008-11, Vol.10 (6), p.374-380
• Main Authors: 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
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - diagnostic imaging; Adenocarcinoma - radiotherapy; Adenocarcinoma - secondary; Adult; Aged; Carbon Radioisotopes - therapeutic use; Female; Humans; Imaging; Male; Medicine; Medicine & Public Health; Methionine; Middle Aged; Neoplasm Recurrence, Local - diagnostic imaging; Pelvic Neoplasms - diagnostic imaging; Positron-Emission Tomography - methods; Prognosis; Prospective Studies; Radiology; Radiopharmaceuticals; Rectal Neoplasms - diagnostic imaging; Rectal Neoplasms - radiotherapy; Research Article
• ISSN: 1536-1632; 1860-2002
• DOI: 10.1007/s11307-008-0156-1

Purpose 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 -[ 11 C]methyl-methionine ( 11 C-methionine) uptake at pre- and post-CIRT could be an early response predictor in patients with pelvic recurrence of rectal cancer. Procedures 11 C-Methionine-positron emission tomography (PET) was performed prospectively in 53 patients with pelvic recurrence of rectal cancer before CIRT, and 48 patients were performed 11 C-methionine PET at 1 month after CIRT. 11 C-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). 11 C-Methionine PET judgment was compared with CT/MRI judgment regarding the relevance to clinical outcome. Results 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 ≦7.6 or a post-CIRT T / M ratio of ≦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 11 C-methionine results (baseline T / M ratio, post-CIRT T / M ratio and percent change) and other clinical parameters (distant metastasis and survival). Conclusion 11 C-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.