Hall Jacob, Dance Michael, Huang Benjamin, Steele Ethan, Nguyen Lorie, Repka Michael, Chen Xuguang, Shen Colette
Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina.
Department of Radiology, University of North Carolina, Chapel Hill, North Carolina.
Adv Radiat Oncol. 2024 Aug 24;9(10):101588. doi: 10.1016/j.adro.2024.101588. eCollection 2024 Oct.
Patients with primary sinonasal and cutaneous head and neck (H&N) malignancies often receive meaningful radiation dose to their hippocampi, but this not a classic avoidance structure in radiation planning. We aimed to characterize the feasibility and tradeoffs of hippocampal-sparing radiation therapy (HSRT) for patients with primary sinonasal and cutaneous H&N malignancies.
We retrospectively selected patients who were treated definitively for primary sinonasal or cutaneous malignancies of the H&N at an academic medical center. All received (chemo)radiation alone or adjuvantly and substantial radiation dose to 1 or both hippocampi. We created new HSRT plans for each patient with intensity modulated radiation therapy using the original target and organ-at-risk (OAR) volumes. Hippocampi were contoured based on Radiation Therapy Oncology Group guidelines and reviewed by a neuroradiologist. Absolute and relative differences in radiation dose to the hippocampi, planning target volumes (PTVs), and OARs were recorded and compared.
There were 18 sinonasal and 12 cutaneous H&N primary tumors (30 patients in total). Median prescription dose was 6600 cGy (range, 5000-7440 cGy), and 14 of the 30 patients received 120 cGy/fraction twice daily, 13 of the 30 patients received 200 cGy/fraction once daily, whereas others received 180-275 cGy/fraction once daily. The relative decrease in ipsilateral hippocampal D and D100% using HSRT was 44% (median, 2009 cGy from 3586 cGy) and 65% (median 434 cGy from 1257 cGy), respectively. There were no statistically significant or clinically meaningful differences in PTV V100%, PTV D1%, or radiation dose to other OARs between HSRT and non-HSRT plans.
HSRT is feasible and results in meaningful dose reduction to the hippocampi without reducing PTV coverage or increasing dose to other OARs. We suggest target hippocampal constraints of D < 1600 cGy and D100% < 500 cGy when feasible (without compromising PTV coverage or impacting other critical OARs). The clinical significance of HSRT in patients with primary H&N tumors should be investigated prospectively.
原发性鼻窦和头颈部皮肤恶性肿瘤患者的海马体常常会接受较高剂量的放疗，但在放疗计划中，海马体并非典型的需避开的结构。我们旨在明确原发性鼻窦和头颈部皮肤恶性肿瘤患者采用海马体保护放疗（HSRT）的可行性及利弊权衡。
我们回顾性选取了在一家学术医疗中心接受原发性鼻窦或头颈部皮肤恶性肿瘤根治性治疗的患者。所有患者均单独或辅助接受了（化疗）放疗，且一侧或双侧海马体接受了较高剂量的放疗。我们使用原始靶区和危及器官（OAR）体积，为每位患者制定了新的调强放疗HSRT计划。海马体根据放射治疗肿瘤学组的指南进行勾画，并由神经放射科医生进行审核。记录并比较海马体、计划靶区（PTV）和OAR所接受的放疗剂量的绝对差异和相对差异。
有18例鼻窦原发性肿瘤和12例头颈部皮肤原发性肿瘤（共30例患者）。中位处方剂量为6600 cGy（范围5000 - 7440 cGy），30例患者中有14例每天两次接受120 cGy/分次，30例患者中有13例每天一次接受200 cGy/分次，其他患者每天一次接受180 - 275 cGy/分次。采用HSRT时，同侧海马体D和D100%的相对降低分别为44%（中位数，从3586 cGy降至2009 cGy）和65%（中位数，从1257 cGy降至434 cGy）。HSRT计划与非HSRT计划在PTV V100%、PTV D1%或其他OAR所接受的放疗剂量方面，均无统计学显著差异或临床意义上的差异。
HSRT是可行的，可在不减少PTV覆盖范围或不增加其他OAR剂量的情况下，显著降低海马体的放疗剂量。我们建议在可行的情况下（不影响PTV覆盖范围或不影响其他关键OAR），将海马体的靶区限制设定为D < 1600 cGy和D100% < 500 cGy。应前瞻性研究HSRT对原发性头颈部肿瘤患者的临床意义。
