Lycke Wind Karen, Garm Spindler Karen-Lise, Maria Lutz Christina, Nyvang Lars, Kronborg Camilla
Department of Experimental Clinical Oncology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
Department of Clinical Medicine, Faculty of Health, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
Phys Imaging Radiat Oncol. 2023 Feb 3;25:100424. doi: 10.1016/j.phro.2023.100424. eCollection 2023 Jan.
Loco-regional recurrence (LRR) dominates the failure pattern after curative radiotherapy in anal cancer. The aim of this study was to estimate dose of LRRs in anal cancer using a point of origin-based method.
Of 321 patients with squamous cell carcinoma of the anus, 31 patients with LRR (29 local recurrences and 5 regional lymph node recurrences) were available for analysis. The recurrence volumes were delineated on recurrence magnetic resonance imaging (rMRI). Rigid and subsequent deformable co-registration of planning computerised tomography scans and rMRI were performed. Point of origin was estimated as the centre of mass (COM) and an observer-based point of origin (obs-PO). Doses to COM and obs-PO, as well as the full recurrence volume, were estimated and the relation to target volumes was extracted.
The median minimum dose to COM was 63.8 Gy (range 32.5-65.1 Gy) and 63.7 Gy (range 35.5-65.2 Gy) to obs-PO of local recurrences. COM was included in the high dose volume (64 Gy) in 86 % of cases, and obs-PO was included in 75 % of cases. There was no difference in minimum dose to COM and obs-PO, and the median distance between the two points was 3.3 mm (range 0.6-19.8 mm). No recurrences occurred in primarily boosted lymph nodes.
The majority of LLRs were located within the high dose volume indicating radioresistance as the primary cause of recurrence in anal cancer. No difference between the use of COM and obs-PO was evident.
局部区域复发（LRR）是肛管癌根治性放疗后主要的失败模式。本研究的目的是使用基于起源点的方法估计肛管癌LRR的剂量。
在321例肛门鳞状细胞癌患者中，31例发生LRR（29例局部复发和5例区域淋巴结复发）的患者可供分析。在复发磁共振成像（rMRI）上勾勒出复发体积。对计划计算机断层扫描和rMRI进行刚性及随后的可变形配准。起源点估计为质心（COM）和基于观察者的起源点（obs-PO）。估计COM和obs-PO以及整个复发体积的剂量，并提取与靶体积的关系。
局部复发的COM的中位最小剂量为63.8 Gy（范围32.5 - 65.1 Gy），obs-PO为63.7 Gy（范围35.5 - 65.2 Gy）。86%的病例中COM包含在高剂量体积（64 Gy）内，75%的病例中obs-PO包含在高剂量体积内。COM和obs-PO的最小剂量无差异，两点之间的中位距离为3.3 mm（范围0.6 - 19.8 mm）。主要增强的淋巴结未发生复发。
大多数LLR位于高剂量体积内，表明放射抗性是肛管癌复发的主要原因。使用COM和obs-PO之间没有明显差异。
