Baumann M, Petersen C, Schulz P, Baisch H
Clinic of Radiation Oncology, Medical Faculty Carl Gustav Carus, Technical University of Dresden, Germany.
Radiother Oncol. 1999 Jan;50(1):107-11. doi: 10.1016/s0167-8140(98)00112-1.
The impact of overall treatment time of fractionated irradiation on local control of slow growing human GL squamous cell carcinoma (SCC) was determined.
Moderately well differentiated and keratinizing human GL SCC with a volume doubling time of 8 days were transplanted subcutaneously into the right hindleg of NMRI (nu/nu) mice and irradiated with 30 fractions under ambient conditions over 2, 3, 4.5, 6 and 10 weeks. Endpoint of the experiments was local tumor control at day 180 after end of treatment.
The tumor control dose 50% (TCD50) increased from 40 to 57 Gy when the treatment time was extended from 2 to 10 weeks. The data can be well described by a linear increase in TCD50 with time. The recovered dose per day (D(r)) was 0.28 Gy (95% confidence interval 0.06; 0.48). The fit to the data was not significantly improved by assuming a biphasic (dog-leg) time course with constant TCD50 values in the initial part of treatment followed by a more rapid increase of TCD50 thereafter.
D(r) in GL SCC was significantly less than the value of 1.0 Gy (0.7; 1.3) previously reported for poorly differentiated, non-keratinizing and fast growing human FaDu SCC (Baumann M, Liertz C, Baisch H, Wiegel T, Lorenzen J, Arps H. Impact of overall treatment time of fractionated irradiation on local control of human FaDu squamous cell carcinoma in nude mice. Radiother. Oncol. 1994:32:137-143), indicating important heterogeneity of the time factor between different tumors of the same histological type.
确定分次照射的总治疗时间对生长缓慢的人舌鳞状细胞癌（SCC）局部控制的影响。
将体积倍增时间为8天的中度分化且角化的人舌SCC皮下移植到NMRI（nu/nu）小鼠的右后肢，并在环境条件下于2、3、4.5、6和10周内给予30次分割照射。实验终点为治疗结束后第180天的局部肿瘤控制情况。
当治疗时间从2周延长至10周时，肿瘤控制剂量50%（TCD50）从40 Gy增加至57 Gy。TCD50随时间呈线性增加，能很好地描述这些数据。每日恢复剂量（D(r)）为0.28 Gy（95%置信区间0.06；0.48）。假设采用双相（折线）时间进程，即治疗初期TCD50值恒定，随后TCD50更快速增加，对数据的拟合并未显著改善。
舌SCC的D(r)显著低于先前报道的低分化、非角化且生长快速的人FaDu SCC的1.0 Gy（0.7；1.3）值（鲍曼M，利尔茨C，拜施H，维格尔T，洛伦岑J，阿普斯H。分次照射的总治疗时间对裸鼠人FaDu鳞状细胞癌局部控制的影响。放射肿瘤学。1994年；32：137 - 143），表明同一组织学类型的不同肿瘤之间时间因素存在重要异质性。
