表观扩散系数预测直肠癌术前放化疗疗效分析

Predictive value of apparent diffusion coefficient for efficacy of preoperative chemoradiotherapy for locally advanced rectal cancer

目的 探讨表观扩散系数（ADC）预测局部晚期直肠癌术前放化疗疗效的作用.方法 2007-2011年间前瞻性纳入病理证实的临床Ⅱ、Ⅲ期直肠腺癌患者70例.均行术前同期放化疗,盆腔放疗44.0 ～50.4 Gy分22 ～ 28次,同期化疗卡培他滨每天1 650 mg/m2第1 ～ 35天＋奥沙利铂50mg/m2每周1次共5次,放化疗后4～8周行根治性手术.疗前常规行盆腔MRI及扩散加权成像检查,测量ADC值并行术后病理反应评级.Mann-Whitney U检验法分析组间ADC值差异,Kaplan-Meier法计算生存率并Logrank法检验.结果 70例患者中7例（10％） pCR、38例（54％）降期.中位随访34个月,22例（31％）复发.疗前、疗中、疗后平均ADC值分别为（1.09±0.19） ×10-3、（1.28±0.19）×10-3、（1.47 ±0.24）×10-3 mm2/s.预后较好组（pCR、降期、无复发）疗前平均ADC值低于预后不良组（P =0.049、0.001、0.029）.取疗前ADC值1.06×10-3 mm2/s为界值预测降期,ROC曲线下面积为0.737（95％CI=0.618 ～0.856）.疗前ADC值＜1.06 ×10-3 mm2/s组3年DFS和DMFS均高于≥1.06×10-3 mm2/s组,分别为86％比58％ （P =0.01）和90％比60％ （P =0.01）.结论 疗前ADC值与局部晚期直肠癌术前同期放化疗疗效有一定相关性,对预测直肠癌术前放化疗疗效有一定意义.

Objective To investigate the value of apparent diffusion coefficient （ADC） in predicting the efficacy of preoperative chemoradiotherapy （PCRT） for locally advanced rectal cancer.Methods From 2007 to 2011,70 patients with histopathologically proven clinical stage Ⅱ / Ⅲ rectal cancer were enrolled prospectively.All patients received PCRT,with radiotherapy （44.0-50.4 Gy/22-28 fractions） delivered to the pelvis and concurrent chemotherapy with capecitabine （l 650 mg/m2 per day,d 1-35） and oxaliplatin （50 mg/m2,once weekly,5 times）,and radical surgery performed at 4-8 weeks after PCRT.Diffusion-weighted MRI was performed in all patients before PCRT,and ADC values were calculated.The pathologic tumor regression grade was assessed after surgery.The difference in ADC between groups was analyzed by nonparametric Mann-Whitney U test.Survivals were analyzed by the Kaplan-Meier method and compared by the log-rank test.Results Among 70 patients,7 （10%） achieved a pathological complete response （pCR）,and 38 （54%） were downstaged.With a median follow-up of 34 months,22 （31%） patients experienced recurrence.The mean ADC values before,during,and after PCRT （pre-ADC,during-ADC,and post-ADC） were （1.09 ± 0.19） × 10-3 mm2/s,（1.28 ± 0.19） × 10-3 mm2/s,and （1.47 ± 0.24） × 10-3 mm2/s,respectively.The mean pre-ADCs for favorable groups （pCR,downstaging,and no recurrence） were significantly lower than those for unfavorable groups （P=0.049,0.001,and 0.029）.When a pre-ADC value of 1.06 × 10-3 mm2 / s was used as the cut-off value for predicting downstaging,the area under the receiver operating characteristic curve was 0.737 （95%CI =0.618-0.856）.The 3-year disease-free survival and distant metastasis-free survival for patients with pre-ADCs of 〈 1.06 × 10-3 mm2/s were 86% and 90%,respectively,which were significantly higher than those for patients with pre-ADCs of ≥ 1.06 × 10-3 mm2/s （58% and 60%） （P =0.010 for both）.Conclusions Pre-ADC correlates to the efficacy of PCRT for locally advanced rectal cancer,so it has good prognostic value for this disease after PCRT.