Yanagawa Takashi, Okamoto Masahiko, Ohno Tatsuya, Chikuda Hirotaka
Department of Musculoskeletal Oncology, Gunma Prefectural Cancer Center, Maebashi, Japan.
Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Showa, Maebashi, Japan.
Oncology. 2025;103(1):30-36. doi: 10.1159/000540649. Epub 2024 Aug 12.
Recent reports have described the usefulness of carbon ion radiotherapy (CIRT) for inoperable sacral chordomas. However, its long-term local control rate needs to be improved. The present study identified the risk factors that affect the local relapse of sacral chordomas and the appropriate margins from the tumors.
Forty-nine patients with sacral chordoma treated with CIRT between 2011 and 2022 were retrospectively analyzed. Factors predicting the risk of local recurrence were evaluated, including age, sex, tumor size, muscle invaded with tumor, and surgery before CIRT. To determine the appropriate margin, the distance between the clinical target volume (CTV) and the out-field recurrent lesions was analyzed.
The patients included 37 males and 12 females with a mean age of 67.1 years. A multivariate analysis showed that a tumor size >8 cm and invasion into the gluteus maximus muscle were significant risk factors with hazard ratios of 5.56 and 15.20 (p = 0.02 and 0.01), respectively. Out-field recurrence occurred in 13 cases, with 6, 3, and 4 relapses occurring in the muscle, bone, and both, respectively. The tumor occurred within 20 mm from the CTV in 60% of relapses in the muscles.
The current study presented novel findings on CIRT for sacral chordomas, although there were several limitations, such as a short follow-up period to investigate slow-growth tumors and a small number of tumor specimens owing to inoperative cases. A tumor size >8 cm and invasion into the gluteus maximus muscle were shown to be risk factors for recurrence in the treatment of sacral chordoma with CIRT. Our findings further suggest that an additional 2-cm margin from the CTV in the muscle fiber direction is recommended during CIRT.
最近的报告描述了碳离子放射治疗（CIRT）对无法手术切除的骶骨脊索瘤的有效性。然而，其长期局部控制率仍有待提高。本研究确定了影响骶骨脊索瘤局部复发的危险因素以及距肿瘤的合适边界。
回顾性分析了2011年至2022年间接受CIRT治疗的49例骶骨脊索瘤患者。评估了预测局部复发风险的因素，包括年龄、性别、肿瘤大小、肿瘤侵犯的肌肉以及CIRT前的手术情况。为确定合适的边界，分析了临床靶体积（CTV）与野外复发病变之间的距离。
患者包括37名男性和12名女性，平均年龄67.1岁。多因素分析显示，肿瘤大小>8 cm和侵犯臀大肌是显著的危险因素，风险比分别为5.56和15.20（p = 0.02和0.01）。野外复发13例，其中肌肉、骨骼及两者均复发的分别有6例、3例和4例。60%的肌肉复发肿瘤发生在距CTV 20 mm范围内。
本研究提出了关于CIRT治疗骶骨脊索瘤的新发现，尽管存在一些局限性，如随访期短难以研究生长缓慢的肿瘤以及因无法手术的病例导致肿瘤标本数量少。肿瘤大小>8 cm和侵犯臀大肌被证明是CIRT治疗骶骨脊索瘤复发的危险因素。我们的研究结果进一步表明，在CIRT期间，建议在肌肉纤维方向上距CTV额外增加2 cm的边界。
