Chilukuri Srinivas, Burela Nagarjuna, Sundar Sham, Kamath Ramakrishna, Nangia Sapna, Arjunan Manikandan, Kumar Roopesh, Ramanujam Vishnu, Chacko Ari, Sharma Dayananda Shamurailatpam, Jalali Rakesh
Department of Radiation Oncology, Apollo Proton Cancer Centre, Chennai, Tamil Nadu, India.
Department of Medical Physics, Apollo Proton Cancer Centre, Chennai, Tamil Nadu, India.
Adv Radiat Oncol. 2024 Jul 28;9(10):101582. doi: 10.1016/j.adro.2024.101582. eCollection 2024 Oct.
To critically review the clinical factors, dosimetry, and their correlation with early outcomes in patients with chordomas and chondrosarcomas treated with pencil beam scanning (PBS) proton beam therapy (PBT).
Consecutive 64 patients diagnosed with chordoma or chondrosarcoma treated at our center were studied. Patient, tumor, and treatment-related factors including dosimetry were captured. Early and late toxicities and early outcomes were evaluated and correlated with clinical and dosimetric factors using standard statistical tools.
The median age of patients was 39 years (range, 4-74 years), and most common site was skull base (47%), followed by sacrum (31%) and mobile spine (22%). The median prescription dose to the high-risk clinical target volumes for chordoma and chondrosarcoma was 70.4 cobalt gray equivalent (CGE) and 66 CGE at 2.2 CGE per fraction, respectively. At presentation, 55% presented after a recurrence/progression of which 17% had received previous radiation and 32% had a significant neural compression. At the time of PBT, 25% of patients had suboptimal neural separation. Three-fourths of patients had at least an acceptable target coverage. Although 11% had a tier 1 compromise (gross tumor volume [GTV] D98 < 90%), 14% had a tier 2 compromise (GTVD98 < 59 CGE). With a median follow-up of 27.5 months, 2-year local control and progression-free survival was 86.7% and 81.8% for chordomas and 87.5% and 77.1% for chondrosarcomas, respectively. Residual GTV of >25 cm and a tier 2 compromise were associated with inferior local control (hazard ratio [HR], 0.19; = .019; HR, 0.061; = .022, respectively) and progression-free survival (HR, 0.128; = 0.014; HR, 0.194; =.025, respectively) on multivariate analysis. Despite multiple surgeries, a majority presented with recurrent disease and previous radiations and grade 3 acute and late toxicities were limited and comparable with others in the literature.
Despite multiple surgeries, adequate neural separation was challenging to achieve. Severe dosimetric compromise (GTV D98 < 59 CGE) led to inferior early outcomes. Adequate neural separation is key to avoiding dosimetric compromise and achieving optimal local control.
严格审查接受笔形束扫描（PBS）质子束治疗（PBT）的脊索瘤和软骨肉瘤患者的临床因素、剂量测定及其与早期结果的相关性。
对在我们中心接受治疗的64例连续诊断为脊索瘤或软骨肉瘤的患者进行研究。记录患者、肿瘤及与治疗相关的因素，包括剂量测定。使用标准统计工具评估早期和晚期毒性以及早期结果，并将其与临床和剂量学因素相关联。
患者的中位年龄为39岁（范围4 - 74岁），最常见的部位是颅底（47%），其次是骶骨（31%）和活动脊柱（22%）。脊索瘤和软骨肉瘤高危临床靶区的中位处方剂量分别为70.4钴灰当量（CGE）和66 CGE，每次分割剂量为2.2 CGE。就诊时，55%的患者为复发/进展后就诊，其中17%曾接受过放疗，32%有明显神经受压。在接受PBT时，25%的患者神经分离欠佳。四分之三的患者至少有可接受的靶区覆盖。虽然11%的患者存在一级妥协（大体肿瘤体积[GTV] D98 < 90%），但14%的患者存在二级妥协（GTVD98 < 59 CGE）。中位随访27.5个月，脊索瘤的2年局部控制率和无进展生存率分别为86.7%和81.8%，软骨肉瘤分别为87.5%和77.1%。多因素分析显示，残留GTV > 25 cm和二级妥协与较差的局部控制（风险比[HR]分别为0.19；P = 0.019；HR为0.061；P = 0.022）和无进展生存率（HR分别为0.128；P = 0.014；HR为0.194；P = 0.025）相关。尽管进行了多次手术，但大多数患者仍表现为复发性疾病且曾接受过放疗，3级急性和晚期毒性有限，与文献中的其他研究相当。
尽管进行了多次手术，但实现充分的神经分离仍具有挑战性。严重的剂量测定妥协（GTV D98 < 59 CGE）导致较差的早期结果。充分的神经分离是避免剂量测定妥协和实现最佳局部控制的关键。
