Dosimetric analysis of radiation-induced brainstem necrosis for nasopharyngeal carcinoma treated with IMRT

Abstract

Background Radiation-induced brainstem necrosis (RIBN) is a late life-threatening complication that can appear after treatment in patients with nasopharyngeal carcinoma (NPC). However, the relationship between RIBN and radiation dose is not still well-defined. Methods During January 2013 and December 2017, a total of 1063 patients with NPC were treated at Sichuan cancer hospital with IMRT. A total of 479 patients were eligible for dosimetric analysis. Dosimetric parameters of the RIBN, Dmax(the maximum dose), D0.1c (maximum average dose delivered to a 0.1-cc volume), D1cc, D2cc, D3cc, D5cc, D10cc and Dmean (mean does) were evaluated and recorded. ROC curve was used to analyze the area under curve (AUC) and cutoff points. Logistic regression for screening dose-volume parameter and logistic dose response model were used to predict the incidence of brainstem necrosis. Results Among the 479 patients with NPC, 6 patients were diagnosed with RIBN, the incidence of RIBN was 1.25% (6/479), and the median time to RIBN after treatment was 28.5 months (range 18–48 months). The dose of the brainstem in patients with RIBN were higher than that in patients without necrosis. ROC curve showed that the area under the curve (AUC) of Dmax was the largest (0.987). Moreover, logistic stepwise regression indicated that Dmax was the most important dose factor. The RIBN incidence at 5% over 5 years (TD5/5) and 50% incidence over 5 years (TD50/5) was 69.59 Gy and76.45 Gy, respectively. Conclusions Brainstem necrosis is associated with high dose irritation. Dmax is the most significant predictive dosimetric factor for RIBN. Dmax of brainstem should be considered as the dose limitation parameter. We suggest that the limitation dose for brainstem was Dmax < 69.59 Gy.

Excessively Delayed Radiation Changes After Proton Beam Therapy for Brain Tumors: Report of Two Cases

“…In a study by Andruska et al [ 5 ], a large fraction dose of 30 Gy/5 fractions for brain metastasis resulted in a 15% incidence of RN, which occurred at a median of 6.9 months after treatment. In contrast, smaller fraction doses with a higher number of fractions (5,500–7,500 cGy/30–36 fractions) were associated with a 1.3% incidence of brainstem necrosis at a median of 28.5 months after intensity-modulated RT for nasopharyngeal cancer [ 14 ].…”

Specific-CT brain template construction and retrospective dosimetric comparison study in brain for nasopharyngeal carcinoma patients treated with IMRT or VMAT

“…For example, Cheng-Yun Yao et al [39] analyzed 327 patients with NPC undergoing IMRT and discovered that 8 had brainstem damage caused by radiation. Xi-Gang Fan et al [40] discovered that radiation-induced brainstem necrosis was identified in 6 out of 479 NPC patients. The maximum brainstem dose was discovered to be greater in individuals with radiation-induced brainstem necrosis than in those without the condition.…”

A detailed dosimetric comparative study of IMRT and VMAT in normal brain tissues for nasopharyngeal carcinoma patients treated with radiotherapy

“…Cheng-Yun Yao ( 36 ) et al reviewed 327 patients with NPC receiving IMRT and found that 8 patients had radiation-induced brainstem injuries. Xiang Fan et al ( 37 ) found that among 479 patients with NPC, six patients were diagnosed with RT-induced brainstem necrosis. They found the maximum dose (D max ) of the brainstem in patients with RT-induced brainstem necrosis was greater than that in patients without necrosis.…”