Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China.
Evidance Medical Technologies Inc., Suzhou, China.
Radiother Oncol. 2019 Jul;136:98-105. doi: 10.1016/j.radonc.2019.03.035. Epub 2019 Apr 15.
To evaluate the outcomes of 45 Gy/15 fractions/once-daily and 45 Gy/30 fractions/twice-daily radiation schemes utilizing intensity-modulated radiation therapy (IMRT) in extensive stage small cell lung cancer (SCLC), and to build up a new radiobiological model for tumor control probability (TCP) considering multiple biological effects.
Fifty-eight consecutive patients diagnosed with extensive stage SCLC, treated with chemotherapy and chest irradiation, were retrospectively reviewed. Thirty-seven received hyperfractionated IMRT (Hyper-IMRT, 45 Gy/30 fractions/twice-daily) and 21 received hypofractionated IMRT (Hypo-IMRT, 45 Gy/15 fractions/once-daily). Local progression-free survival (LPFS) and overall survival (OS) were calculated and compared. An extended linear-quadratic (LQ) model, LQRG, incorporating cell repair, redistribution, reoxygenation, regrowth and Gompertzian tumor growth was created based on the clinical data. The TCP model was reformulated to predict LPFS. The classical LQ and TCP models were compared with the new models. Akaike information criterion (AIC) was used to assess the quality of the models.
The 2-year LPFS (34.1% vs 27.9%, p = 0.44) and OS (76.9% vs 76.9%, p = 0.26) were similar between Hyper- and Hypo-IMRT patients. According to the LQRG model, the α/β calculated was 9.2 (95% confidence interval: 8.7-9.9) Gy after optimization. The average absolute and relative fitting errors for LPFS were 9.1% and 18.7% for Hyper-IMRT, and 8.8% and 16.2% for Hypo-IMRT of the new TCP model, compared with 29.1% and 62.3% for Hyper-IMRT, and 30.7% and 65.3% for Hypo-IMRT of the classical model.
Hypo- and Hyper-IMRT resulted in comparable local control in the chest irradiation of extensive stage SCLC. The LQRG model has better performance in predicting the TCP (or LPFS) of the two schemes.
评估采用调强放疗（IMRT）的 45Gy/15 次/日单次和 45Gy/30 次/日双次分割方案在广泛期小细胞肺癌（SCLC）中的疗效，并建立一个新的考虑多种生物学效应的肿瘤控制概率（TCP）的放射生物模型。
回顾性分析了 58 例经化疗和胸部放疗的广泛期 SCLC 患者，其中 37 例接受超分割 IMRT（Hyper-IMRT，45Gy/30 次/日双次），21 例接受低分割 IMRT（Hypo-IMRT，45Gy/15 次/日单次）。计算并比较局部无进展生存期（LPFS）和总生存期（OS）。基于临床数据，建立了一个扩展的线性二次（LQ）模型，即 LQRG，其中包括细胞修复、再分布、再氧合、再生长和 Gompertz 肿瘤生长。对 TCP 模型进行了重新制定，以预测 LPFS。将经典的 LQ 和 TCP 模型与新模型进行了比较。采用赤池信息量准则（AIC）评估模型的质量。
Hyper-IMRT 和 Hypo-IMRT 患者的 2 年 LPFS（34.1% vs 27.9%，p=0.44）和 OS（76.9% vs 76.9%，p=0.26）相似。根据 LQRG 模型，经优化后计算出的α/β为 9.2（95%置信区间：8.7-9.9）Gy。新 TCP 模型中，Hyper-IMRT 的 LPFS 平均绝对和相对拟合误差分别为 9.1%和 18.7%，Hypo-IMRT 分别为 8.8%和 16.2%，而经典模型中，Hyper-IMRT 的分别为 29.1%和 62.3%，Hypo-IMRT 的分别为 30.7%和 65.3%。
Hypo- 和 Hyper-IMRT 在广泛期 SCLC 的胸部放疗中均能获得相似的局部控制。LQRG 模型在预测两种方案的 TCP（或 LPFS）方面表现更好。
