Harvard Radiation Oncology Program, Harvard Medical School, Boston, MA, USA.
Int J Radiat Oncol Biol Phys. 2012 Jul 15;83(4):e495-500. doi: 10.1016/j.ijrobp.2011.10.056. Epub 2012 Jan 26.
To calculated projected second tumor rates and dose to organs at risk (OAR) in patients with benign intracranial meningioma (BM), according to dosimetric comparisons between proton radiotherapy (PRT) and photon radiotherapy (XRT) treatment plans.
Ten patients with BM treated at Massachusetts General Hospital during 2006-2010 with PRT were replanned with XRT (intensity-modulated or three-dimensional conformal radiotherapy), optimizing dose to the tumor while sparing OAR. Total dose was 54 Gy in 1.8 Gy per fraction for all plans. We calculated equivalent uniform doses, normal tissue complication probabilities, and whole brain-based estimates of excess risk of radiation-associated intracranial second tumors.
Excess risk of second tumors was significantly lower among PRT compared with XRT plans (1.3 vs. 2.8 per 10,000 patients per year, p < 0.002). Mean equivalent uniform doses were lower among PRT plans for the whole brain (19.0 vs. 22.8 Gy, p < 0.0001), brainstem (23.8 vs. 35.2 Gy, p = 0.004), hippocampi (left, 13.5 vs. 25.6 Gy, p < 0.0001; right, 7.6 vs. 21.8 Gy, p = 0.001), temporal lobes (left, 25.8 vs. 34.6 Gy, p = 0.007; right, 25.8 vs. 32.9 Gy, p = 0.008), pituitary gland (29.2 vs. 37.0 Gy, p = 0.047), optic nerves (left, 28.5 vs. 33.8 Gy, p = 0.04; right, 25.1 vs. 31.1 Gy, p = 0.07), and cochleas (left, 12.2 vs. 15.8 Gy, p = 0.39; right,1.5 vs. 8.8 Gy, p = 0.01). Mean normal tissue complication probability was <1% for all structures and not significantly different between PRT and XRT plans.
Compared with XRT, PRT for BM decreases the risk of RT-associated second tumors by half and delivers significantly lower doses to neurocognitive and critical structures of vision and hearing.
根据质子放射治疗（PRT）和光子放射治疗（XRT）计划的剂量比较，计算良性颅内脑膜瘤（BM）患者的预计二次肿瘤发生率和危及器官（OAR）剂量。
2006 年至 2010 年期间，在马萨诸塞州综合医院接受 PRT 治疗的 10 名 BM 患者被重新计划进行 XRT（调强或三维适形放疗），同时优化肿瘤剂量，同时保护 OAR。所有计划的总剂量均为 54 Gy，分次 1.8 Gy。我们计算了等效均匀剂量、正常组织并发症概率以及基于全脑的辐射相关颅内二次肿瘤超额风险估计。
与 XRT 计划相比，PRT 计划的二次肿瘤风险显著降低（每 10,000 名患者每年分别为 1.3 例和 2.8 例，p < 0.002）。PRT 计划全脑（19.0 与 22.8 Gy，p < 0.0001）、脑干（23.8 与 35.2 Gy，p = 0.004）、海马（左，13.5 与 25.6 Gy，p < 0.0001；右，7.6 与 21.8 Gy，p = 0.001）、颞叶（左，25.8 与 34.6 Gy，p = 0.007；右，25.8 与 32.9 Gy，p = 0.008）、垂体（29.2 与 37.0 Gy，p = 0.047）、视神经（左，28.5 与 33.8 Gy，p = 0.04；右，25.1 与 31.1 Gy，p = 0.07）和耳蜗（左，12.2 与 15.8 Gy，p = 0.39；右，1.5 与 8.8 Gy，p = 0.01）的等效均匀剂量均较低。所有结构的正常组织并发症概率均<1%，且 PRT 和 XRT 计划之间无显著差异。
与 XRT 相比，BM 的 PRT 将 RT 相关的二次肿瘤风险降低了一半，并使神经认知和视觉、听觉关键结构的剂量显著降低。
