Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
Cancer. 2012 Apr 15;118(8):2078-84. doi: 10.1002/cncr.26470. Epub 2011 Aug 25.
The most common regimen of stereotactic body radiotherapy (SBRT) for stage I nonsmall cell lung cancer in Japan is 48 grays (Gy) in 4 fractions over 4 days. Radiobiologically, however, higher doses are necessary to control larger tumors, and interfraction intervals should be >24 hours to take advantage of reoxygenation. In this study, the authors tested the following regimen: For tumors that measured <1.5 cm, 1.5 to 3.0 cm, and >3.0 cm in greatest dimension, radiation doses of 44 Gy, 48 Gy, and 52 Gy, respectively, were given in 4 fractions with interfraction intervals of ≥3 days.
Among 180 patients with histologically proven disease who entered the study, 120 were medically inoperable, and 60 were operable. The median patient age was 77 years (range, 29-92 years). SBRT was performed with 6-megavolt photons using 4 noncoplanar beams and 3 coplanar beams. Isocenter doses of 44 Gy, 48 Gy, and 52 Gy were received by 4 patients, 124 patients, and 52 patients, respectively.
The overall survival rate for all 180 patients was 69% at 3 years and 52% at 5 years. The 3-year survival rate was 74% for operable patients and 59% for medically inoperable patients (P = .080). The 3-year local control rate was 86% for tumors ≤3 cm (44/48 Gy) and 73% for tumors >3 cm (52 Gy; P = .050). Grade ≥2 radiation pneumonitis developed in 13% of patients (10% of the 44-Gy/48-Gy group and 21% of the 52-Gy group; P = .056). All other grade 2 toxicities developed in <4% of patients.
The SBRT protocol used in this study yielded reasonable local control and overall survival rates and acceptable toxicity. Dose escalation is being investigated.
在日本，Ⅰ期非小细胞肺癌立体定向体放射治疗（SBRT）最常见的方案是 4 天内进行 4 次分割，每次 48 戈瑞（Gy）。然而，从放射生物学的角度来看，为了控制较大的肿瘤，需要更高的剂量，并且分次间隔时间应大于 24 小时，以利用再氧合作用。在这项研究中，作者测试了以下方案：对于最大尺寸<1.5cm、1.5-3.0cm 和>3.0cm 的肿瘤，分别给予 44Gy、48Gy 和 52Gy 的放射剂量，分次间隔时间均大于 3 天。
在 180 名患有经组织学证实疾病的患者中，120 名患者因身体状况无法手术，60 名患者可以手术。中位患者年龄为 77 岁（范围，29-92 岁）。SBRT 采用 6 兆伏光子，使用 4 个非共面射束和 3 个共面射束进行。4 名患者、124 名患者和 52 名患者分别接受了 44Gy、48Gy 和 52Gy 的等中心点剂量。
所有 180 名患者的总生存率在 3 年时为 69%，在 5 年时为 52%。手术患者的 3 年生存率为 74%，非手术患者为 59%（P=0.080）。肿瘤≤3cm（44Gy/48Gy）的 3 年局部控制率为 86%，肿瘤>3cm（52Gy）的 3 年局部控制率为 73%（P=0.050）。13%的患者发生≥2 级放射性肺炎（44Gy/48Gy 组为 10%，52Gy 组为 21%；P=0.056）。其他所有 2 级毒性反应的发生率均低于 4%。
本研究中使用的 SBRT 方案产生了合理的局部控制率和总生存率，且毒性反应可接受。目前正在研究剂量递增。
