Deore S M, Sarin R, Dinshaw K A, Shrivastava S K
Department of Medical Physics, Tata Memorial Hospital, Parel, Bombay, India.
Int J Radiat Oncol Biol Phys. 1993 Jul 15;26(4):601-6. doi: 10.1016/0360-3016(93)90275-z.
To study the influence of Iridium 192 implant dose-rate and dose per fraction of external irradiation on clinical outcome, the results in 289 patients with early breast cancer were analyzed retrospectively.
From 1980 to 1990, 118 T1 and 171 T2 lesions of breast were treated definitively by radiotherapy, following conservative surgery. External irradiation dose of 45 Gy was delivered either with 2.5 Gy or 1.8 Gy per fraction to the entire target volume, plus boost to the primary tumor. Boost dose of 15 to 30 Gy was given to the primary tumor either with iridium-192 implants or electrons. The implant dose-rate varied between 20 cGy/hr to 160 cGy/hr.
The minimum follow-up was of 12 months and maximum of 11 years (median: 56 months). Out of 273 tumors boosted with implants, the 270 patients were divided into five groups according to dose-rate as, groups 1 (20-29 cGy/hr, n = 17), group 2 (30-49 cGy/hr, n = 144), group 3 (50-69 cGy/hr, n = 69), group 4 (70-99 cGy/hr, n = 27) and group 5 (100-160 cGy/hr, n = 13). The local failure rate was significantly increased in the group of patients treated with implant dose-rate < 30 cGy/hr (p < 0.05). While the incidence of late normal tissue complications and poor cosmetic outcome was significantly higher in the group of patients treated with implant dose-rate > 100 cGy/hr (p < 0.05).
The present analysis indicate that the implant dose-rate should be maintained between 30-70 cGy/hr to maximize local control and reduce the late normal tissue injury. Also the increase in dose per fraction of external irradiation while not influencing local control rate was crucial for incidence of late complications and cosmetic outcome.
为研究铱192植入剂量率和外照射每次分割剂量对临床结果的影响，对289例早期乳腺癌患者的结果进行回顾性分析。
1980年至1990年，118例T1期和171例T2期乳腺病变在保乳手术后接受了根治性放疗。整个靶区接受45 Gy的外照射，每次分割剂量为2.5 Gy或1.8 Gy，同时对原发肿瘤进行加量照射。原发肿瘤的加量剂量为15至30 Gy，采用铱192植入或电子线照射。植入剂量率在20 cGy/小时至160 cGy/小时之间变化。
最短随访时间为12个月，最长为11年（中位值：56个月）。在273例接受植入加量照射的肿瘤患者中，270例患者根据剂量率分为五组，即第1组（20 - 29 cGy/小时，n = 17）、第2组（30 - 49 cGy/小时，n = 144）、第3组（50 - 69 cGy/小时，n = 69）、第4组（70 - 99 cGy/小时，n = 27）和第5组（100 - 16 cGy/小时，n = 13）。植入剂量率< 30 cGy/小时的患者组局部失败率显著增加（p < 0.05）。而植入剂量率> 100 cGy/小时的患者组晚期正常组织并发症发生率和美容效果差的发生率显著更高（p < 0.05）。
目前的分析表明，植入剂量率应维持在30 - 70 cGy/小时之间，以最大限度地提高局部控制率并减少晚期正常组织损伤。此外，外照射每次分割剂量的增加虽然不影响局部控制率，但对晚期并发症发生率和美容效果至关重要。
