Target coverage and local recurrences after radiotherapy for sinonasal cancer in Denmark 2008–2015. A DAHANCA study

The study aimed to investigate the pattern of failure and describe compromises in the definition and coverage of the target for patients treated with curatively intended radiotherapy (RT) for sinonasal cancer (SNC). Patients treated with curatively intended RT in 2008–2015 in Denmark for SNC were eligible for the retrospective cohort study. Information regarding diagnosis and treatment was retrieved from the national database of the Danish Head and Neck Cancer Group (DAHANCA). Imaging from the diagnosis of recurrences was collected, and the point of origin (PO) of the recurrent tumour was estimated. All treatment plans were collected and reviewed with the focus on target coverage, manual modifications of target volumes, and dose to organs at risk (OARs) above defined constraints. A total of 184 patients were included in the analysis, and 76 (41%) relapsed. The majority of recurrences involved T-site (76%). Recurrence imaging of 39 patients was evaluated, and PO was established. Twenty-nine POs (74%) were located within the CTV, and the minimum dose to the PO was median 64.1 Gy (3.1–70.7). The criteria for target coverage (V95%) was not met in 89/184 (48%) of the CTV and 131/184 (71%) of the PTV. A total of 24% of CTVs had been manually modified to spare OARs of high-dose irradiation. No difference in target volume modifications was observed between patients who suffered recurrence and patients with lasting remission. The majority of relapses after radical treatment of SNC were located in the T-site (the primary tumour site). Multiple compromises with regards to target coverage and tolerance levels for OARs in the sinonasal region, as defined from RT guidelines, were taken. No common practice in this respect could be derived from the study.

本研究旨在探究鼻鼻窦癌（sinonasal cancer, SNC）患者接受根治性放疗（radiotherapy, RT）后的失败模式，并阐明靶区定义与靶区覆盖度方面的临床妥协情况。本回顾性队列研究的纳入对象为2008年至2015年间丹麦境内因鼻鼻窦癌接受根治性放疗的患者。诊断与治疗相关信息源自丹麦头颈癌小组（Danish Head and Neck Cancer Group, DAHANCA）的国家级数据库。收集复发诊断相关的影像学资料，并估算复发肿瘤的起源点（point of origin, PO）。收集所有治疗计划并进行审查，重点关注靶区覆盖度、靶体积的手动调整，以及超过预设限值的危及器官（organs at risk, OARs）受照剂量。本研究共纳入184例患者进行分析，其中76例（41%）出现复发。多数复发累及T区（占比76%）。对39例患者的复发影像学资料进行评估，明确了其复发肿瘤的起源点。其中29个起源点（74%）位于临床靶区（clinical target volume, CTV）内，起源点的最低受照剂量中位数为64.1 Gy（范围3.1~70.7 Gy）。89例（48%）患者的临床靶区及131例（71%）患者的计划靶区（planning target volume, PTV）未达到靶区覆盖度标准（V95%）。共计24%的临床靶区曾进行手动调整，以降低危及器官的高剂量受照风险。出现复发的患者与持续缓解的患者之间，靶体积调整情况无显著差异。鼻鼻窦癌根治性治疗后，多数复发位于T区（即原发肿瘤部位）。按照放疗指南要求，鼻鼻窦区域危及器官的耐受剂量与靶区覆盖度方面存在多处临床妥协。本研究未发现该领域存在统一的临床实践规范。