Hall-Edwards Radiotherapy Research Group, Cancer Centre, Queen Elizabeth Hospital, Birmingham, UK.
Clin Oncol (R Coll Radiol). 2011 Feb;23(1):29-33. doi: 10.1016/j.clon.2010.08.007. Epub 2010 Sep 9.
There has been a resurgence in interest in radiobiological modelling in head and neck cancer. The aim of this study was to determine if currently used parameters accurately predict both tumour and toxicity outcomes.
Trials were identified from a recent meta-analysis of altered fractionation. The tumour biologically effective dose (tBED; α/β=10Gy, t(k) [onset time of accelerated repopulation]=22 days, t(p) [average doubling time during accelerated repopulation]=3 days, α=0.3Gy(-1)), acute mucosal biologically effective dose (amBED; α/β=10Gy, t(k)=7 days, t(p)=2.5 days, α=0.3Gy(-1)) and late mucosal biologically effective dose (lmBED; α/β=3Gy) were calculated for each arm of each trial. The correlation between the absolute percentage difference in BED between treatment arms and the observed percentage difference in local control, acute grade 3 mucositis and late grade 3 mucosal reaction was then assessed.
A strong correlation was observed between the percentage difference in tBED and the percentage difference in local control (P=0.006). A trend towards a correlation was seen between the percentage difference in amBED and the percentage difference in acute grade 3 mucositis (P=0.06). A significant correlation was observed between the percentage difference in lmBED and the percentage difference in grade 3 late mucosal toxicity (P=0.02). However, a 15% decrease in lmBED between control and experimental arms of the study was necessary for any sparing of late mucosal toxicity to be observed.
Currently used parameters for tumour accurately predict outcomes in randomised trials of altered fractionation. Although the relationship may be more complex for late mucosal reaction, the presence of a correlation is noteworthy given the infrequent reporting or occurrence of this toxicity. In the future, radiobiological modelling with the addition of volumetric parameters will be highly relevant, given attempts to dose escalate with intensity-modulated radiotherapy in poor risk patients and de-escalate in patients with an excellent prognosis.
头颈部癌症的放射生物建模再次受到关注。本研究旨在确定目前使用的参数是否能准确预测肿瘤和毒性结果。
从最近一项改变分割的荟萃分析中确定试验。为每个试验的每个臂计算肿瘤生物有效剂量（tBED；α/β=10Gy，t(k) [加速再增殖的起始时间]=22 天，t(p) [加速再增殖期间的平均倍增时间]=3 天，α=0.3Gy(-1)）、急性黏膜生物有效剂量（amBED；α/β=10Gy，t(k)=7 天，t(p)=2.5 天，α=0.3Gy(-1))和晚期黏膜生物有效剂量（lmBED；α/β=3Gy）。然后评估治疗臂之间 BED 的绝对百分比差异与局部控制、急性 3 级黏膜炎和晚期 3 级黏膜反应的观察百分比差异之间的相关性。
tBED 的百分比差异与局部控制的百分比差异之间存在很强的相关性（P=0.006）。amBED 的百分比差异与急性 3 级黏膜炎的百分比差异之间存在相关性的趋势（P=0.06）。lmBED 的百分比差异与 3 级晚期黏膜毒性的百分比差异之间存在显著相关性（P=0.02）。然而，研究中对照臂和实验组之间的 lmBED 减少 15%，才能观察到晚期黏膜毒性的减轻。
目前用于肿瘤的参数可以准确预测改变分割的随机试验的结果。尽管晚期黏膜反应的关系可能更为复杂，但鉴于这种毒性的报告或发生频率较低，相关性的存在值得注意。未来，随着调强放疗在高危患者中进行剂量递增和在预后良好的患者中进行剂量递减，添加体积参数的放射生物学建模将具有高度相关性。
