Kondziolka D, Somaza S, Comey C, Lunsford L D, Claassen D, Pandalai S, Maitz A, Flickinger J C
Department of Neurological Surgery, University of Pittsburgh, Pennsylvania, USA.
J Neurosurg. 1996 Jun;84(6):1033-8. doi: 10.3171/jns.1996.84.6.1033.
To identify histological changes and effects on survival in rats harboring C6 gliomas, the authors compared radiosurgery to different fractionated radiation therapy regimens including doses of calculated biological equivalence. Rats were randomized to control (54 animals) or treatment groups after implantation of C6 glioma cells into the right frontal brain region. At 14 days, treated rats underwent stereotactic radiosurgery (35 Gy to tumor margin; 22 animals), whole-brain radiation therapy (WBRT) (20 Gy in five fractions; 18 animals), radiosurgery plus WBRT (13 animals), hemibrain radiation therapy (85 Gy in 10 fractions; 16 animals) or single-fraction hemibrain irradiation (35 Gy; 10 animals). When compared to the control group (median survival 22 days), prolonged survival was identified after radiosurgery (p < 0.0001), radiosurgery plus WBRT (p < 0.0001), WBRT alone (p = 0.0002), hemibrain radiation therapy to 85 Gy (p < 0.0001), and 35-Gy hemibrain single-fraction irradiation (p = 0.004). Compared to the control group (mean tumor diameter, 6.8 mm), the tumor size was reduced in all treatment groups except WBRT alone. Reduced tumor cell density was exhibited in rats that underwent radiosurgery (p = 0.006) and radiosurgery plus WBRT (p = 0.009) when compared with rats in the control group, a finding not observed after any fractionated regimen. Increased intratumoral edema was identified after radiosurgery (p = 0.03) and combined treatment (p = 0.05), but not after fractionated radiation therapy or 35-Gy single-fraction hemibrain irradiation. In this animal model, the addition of radiosurgery significantly increased tumor cytotoxicity, potentially at the expense of radiation effects to regional brain. We found no difference in survival benefit or tumor diameter in animals that underwent radiosurgery compared to the calculated biologically equivalent regimen of 10-fraction radiation therapy to 85 Gy. The histological responses after radiosurgery were generally greater than those achieved with biologically equivalent doses of fractionated radiation therapy.
为了确定携带C6胶质瘤大鼠的组织学变化及对生存的影响，作者将立体定向放射外科与不同的分割放射治疗方案（包括计算生物等效剂量）进行了比较。将C6胶质瘤细胞植入大鼠右侧额叶脑区后，将大鼠随机分为对照组（54只动物）或治疗组。在第14天，接受治疗的大鼠接受立体定向放射外科治疗（肿瘤边缘35 Gy；22只动物）、全脑放射治疗（WBRT）（分5次给予20 Gy；18只动物）、立体定向放射外科联合WBRT（13只动物）、半脑放射治疗（分10次给予85 Gy；16只动物）或单次半脑照射（35 Gy；10只动物）。与对照组（中位生存期22天）相比，立体定向放射外科治疗（p < 0.0001）、立体定向放射外科联合WBRT（p < 0.0001）、单纯WBRT（p = 0.0002）、85 Gy半脑放射治疗（p < 0.0001）和35 Gy单次半脑照射（p = 0.004）后生存期延长。与对照组（平均肿瘤直径6.8 mm）相比，除单纯WBRT外，所有治疗组的肿瘤大小均减小。与对照组大鼠相比，接受立体定向放射外科治疗（p = 0.006）和立体定向放射外科联合WBRT（p = 0.009）的大鼠肿瘤细胞密度降低，这一发现未在任何分割方案后观察到。立体定向放射外科治疗（p = 0.03）和联合治疗（p = 0.05）后瘤内水肿增加，但分割放射治疗或35 Gy单次半脑照射后未出现。在该动物模型中，添加立体定向放射外科显著增加了肿瘤细胞毒性，可能以对局部脑区的放射效应为代价。我们发现，与分10次给予85 Gy的计算生物等效方案相比，接受立体定向放射外科治疗的动物在生存获益或肿瘤直径方面没有差异。立体定向放射外科治疗后的组织学反应通常大于生物等效剂量分割放射治疗所达到的反应。
