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鼻咽癌是我国常见恶性肿瘤之一, 在我国头颈部肿瘤中的发病率居首位。由于鼻咽癌特殊的生物学行为以及解剖学部位, 放射治疗是其首选并且是最主要的治疗手段。但由于个体间肿瘤敏感性的不同, 相同放疗剂量能够达到的治疗效果存在着很大的差异。目前多个研究显示, 对于根治性放疗结束后仍有肿瘤残留而采用局部加量治疗, 或局部复发后采用再次放疗治疗, 都可能产生严重的放疗后期反应, 影响患者的生活质量[1-2]。因此, 早期评估放疗疗效, 确定是否需要加量或采用更有效的治疗方式, 制定个体化的治疗方案, 对提高患者的无瘤生存率以及生活质量都有重要的影响。
在评价其他肿瘤治疗效果的研究中显示, 18FFDG PET-CT所反映的细胞代谢水平变化明显先于CT、MRI所反映的形态组织学变化。部分研究还证实, 鼻咽癌组织中细胞增殖核蛋白Ki67表达水平不但与肿瘤的淋巴结转移、远处转移以及临床分期等有联系, 还与鼻咽癌的放疗敏感性密切相关[3-4]。本研究拟通过对18F-FDG PET-CT在裸鼠鼻咽癌移植瘤放疗监测中的应用以及Ki67表达水平的检测, 探讨18F-FDG PET-CT对早期评估裸鼠鼻咽癌移植瘤放疗疗效的作用, 并分析18F-FDG PET-CT与Ki67表达之间的关系。
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对照组裸鼠移植瘤内肿瘤细胞死亡率均小于25%;6 Gy放疗组裸鼠移植瘤内可见约半数肿瘤细胞变性坏死, 死亡率在26%~75%之间; 12 Gy放疗组移植瘤内可见大量肿瘤细胞空泡变性、坏死, 肿瘤周围可见出血及炎性细胞浸润, 其中4只裸鼠肿瘤细胞死亡率在75%以上。(图 1、表 1)
肿瘤细胞死亡率(%) ≤25 25~50 51~75 > 75 对照组 5 0 0 0 6 Gy放疗组 0 3 2 0 12 Gy放疗组 0 1 0 4 表 1 不同实验组裸鼠的肿瘤细胞死亡率情况
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12 Gy放疗组裸鼠移植瘤在放疗后T/NT值不断降低: 放疗前平均T/NT值为2.17±0.31, 放疗6 Gy后平均T/NT值为1.68±0.42, 放疗12 Gy后2 d平均T/NT值为1.41±0.40, 放疗12 Gy后6 d平均T/NT值为0.70±0.12。放疗前与放疗6 Gy时平均T/NT值没有统计学差异(t=2.108, P > 0.05);放疗12 Gy后2 d与放疗前、放疗6 Gy时比较明显减低(与放疗前比较, t=2.80, P < 0.05;与放疗6 Gy时比较t=3.14, P < 0.05);放疗12 Gy后6 d, 移植瘤平均T/NT值较放疗后2 d进一步减低(与放疗后2 d比较, t=3.49, P < 0.05;与放疗前比较, t=8.01, P < 0.01)。
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(1) 鼻咽癌移植瘤Ki67的表达随放疗剂量的增加明显降低, 对照组Ki67的平均表达率为(67.28±9.80)%, 6 Gy放疗组Ki67的平均表达率为(31.94±15.92)%, 12 Gy放疗组Ki67的平均表达率为(9.44±15.22)%, 不同组别间Ki67的表达有明显差异(F=21.95, P < 0.01): 12 Gy放疗组显著低于对照组(t=7.145, P < 0.01)及6 Gy放疗组(t=2.384, P < 0.05);6 Gy放疗组Ki67表达水平也低于对照组(t=4.320, P < 0.01)。
(2) 放疗前移植瘤T/NT值与Ki67表达之间无相关性(P=0.391);放疗过程中移植瘤T/NT值与Ki67表达水平的变化呈正相关(r=0.532, P < 0.05)。
18F-FDG PET-CT对裸鼠鼻咽癌移植瘤放疗疗效的早期评估及与Ki67表达的相关性研究
18F-FDG PET-CT in early assessing the therapeutic effects of nasopharyngeal carcinoma xenograft in nude mice after radiotherapy and it's relativity to the expression of Ki67
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摘要:
目的 探讨18F-FDG PET-CT早期评估裸鼠鼻咽癌移植瘤放疗疗效的价值,并初步分析18F-FDG PET-CT与肿瘤细胞增殖因子Ki67表达之间的关系,为临床进一步研究提供依据。 方法 将15只鼻咽癌裸鼠移植瘤动物模型随机分成3组:每组5只,对照组:行18F-FDG PET-CT后并处死;6 Gy放疗组:于放疗前及放疗后1 d分别给予显像后处死;12 Gy放疗组:于放疗前、放疗6 Gy时、放疗12 Gy后第2 d及6 d时分别行18F-FDG PET-CT,并于最后一次显像后处死。所有裸鼠处死后取移植瘤行病理学检查及Ki67染色,分析放疗疗效与Ki67表达的相关性。 结果 ① 12 Gy放疗组放疗前平均T/NT值为2.17±0.31,放疗6 Gy时平均T/NT值为1.68±0.42,放疗12 Gy后2 d时平均T/NT值为1.41±0.40,放疗12 Gy后6 d时平均T/NT值为0.70±0.12,放疗前与放疗6 Gy时没有统计学差异(t=2.108, P > 0.05);放疗12 Gy后2 d与放疗前、放疗6 Gy时比较明显减低,有统计学差异(与放疗前比较,t=2.80,P < 0.05;与放疗6 Gy时比较,t=3.14,P < 0.05);放疗12 Gy后6 d移植瘤的T/NT值较放疗后2 d进一步减低(与放疗后2 d比较,t=3.49,P < 0.05;与放疗前比较,t=8.01,P < 0.01)。②鼻咽癌移植瘤Ki67的表达随放疗剂量的增加明显降低,不同组别间Ki67的表达有明显差别(F=21.95,P < 0.01):12 Gy放疗组Ki67表达显著低于对照组(t=7.145,P < 0.01)及6 Gy放疗组(t=2.384,P < 0.05);6 Gy放疗组Ki67的表达较对照组减低同样存在统计学意义(t=4.320,P < 0.01)。③放疗前移植瘤T/NT值与Ki67表达之间无相关性。④放疗过程中移植瘤T/NT值的变化与Ki67表达水平呈正相关(r=0.532,P < 0.05)。 结论 18F-FDG PET-CT对早期评估裸鼠鼻咽癌移植瘤的放疗疗效具有重要价值,放疗后6d是一个合适的时间点;18F-FDG PET-CT结合Ki67的表达变化可以反映鼻咽癌的放疗敏感性。 -
关键词:
- 鼻咽肿瘤 /
- 小鼠, 裸 /
- X线疗法 /
- 氟脱氧葡萄糖F18 /
- 正电子发射断层显像术 /
- 体层摄影术, X线计算机 /
- Ki-67, 抗原
Abstract:Objective To investigate the value of 18F-FDG PET-CT scans on early assessing the therapeutic effects on human nasopharyngeal carcinoma(NPC)xenograft in nude mice after radiotherapy, and preliminarily analyze the relation of 18F-FDG PET-CT scans and the positive expression rate of Ki67, and provide a basis for further clinical studies. Methods Fifteen xenograft nude mice of NPC were randomly divided into three groups(5 nude mice per group).Control group: all mice immediately executed after the 18FFDG PET-CT scans and taken pathology; 6 Gy radiotherapy group: all mice took 18F-FDG PET-CT scans before and 1 d after receiving 6 Gy irradiation, and were killed immediately to take pathology; 12 Gy radiotherapy group: all mice received 12 Gy irradiation(6 Gy each time, totally 2 times).They took 18F-FDG PET-CT scans before radiotherapy, after receiving the first 6 Gy irradiation, 2 d and 6 d after receiving 12 Gy irradiation respectively, and then were executed to take pathology after the last scan. The expression of Ki67 in xenografts of different groups was detected and the relation between their changes and T/NT were analyzed. Results ① For 12 Gy radiotherapy group, the average T/NT ratios of the NPC xenograft of pre-radiotherapy, after the first 6 Gy irradiation, 2 d and 6 d after 12 Gy radiotherapy were 2.17±0.31, 1.68±0.42, 1.41±0.40, and 0.70±0.12, respectively. The average T/NT ratios were not statistically difference before and after the first 6 Gy irradiation. The average T/NT ratio of 2 d after radiotherapy decreased significantly than pre-radiotherapy (t=2.80, P < 0.05) and after the first 6 Gy irradiation(t=3.14, P < 0.05); The average T/NT ratio of 6d after radiotherapy was decreased seriously than 2 d after radiotherapy (t=3.49, P < 0.05, compared with pre-radiotherapy t=8.01, P < 0.01). ② The positive expression rates of Ki67 of NPC xenograft markedly decreased after receiving irradiation. There were significant differences in the positive expressions of Ki67 between different groups(F=21.95, P < 0.01).The positive expression of Ki67 in the 12 Gy radiotherapy group decreased significantly compared with the control group (t=7.145, P < 0.01) and the 6 Gy radiotherapy group (t=2.384, P < 0.05). The positive expression of Ki67 in the 6 Gy radiotherapy group was less than the control group, also have statistical significance(t=4.320, P < 0.01).③There was no correlation between the T/NT ratio of NPC xenograft and the positive expression of Ki67. ④Positive correlation was found between the variance of T/NT ratio and the variance of the positive expression of Ki67 of NPC xenograft (r=0.532, P < 0.05). Conclusions 18F-FDG PET-CT imaging has an important value on early assessing the therapeutic effects of NPC xenograft in nude mice after radiotherapy, and the 6th day after radiotherapy is an appropriate time point.18F-FDG PET-CT imaging can reflect the variance of the positive expression of Ki67 of NPC, and yet indirectly reflect the sensitivity of NPC to radiotheraphy. -
表 1 不同实验组裸鼠的肿瘤细胞死亡率情况
肿瘤细胞死亡率(%) ≤25 25~50 51~75 > 75 对照组 5 0 0 0 6 Gy放疗组 0 3 2 0 12 Gy放疗组 0 1 0 4 -
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