直肠癌术前放化疗效果与术后降分期对照研究

MRI volumetry,T downstaging,N staging in evaluating therapeutic effects in advanced rectal carcinoma with preoperative chemoradiotherapy:a comparative study

目的探讨直肠癌术前放化疗的应用价值。方法对北京肿瘤医院2004年12月至2006年10月收治的42例原发性直肠癌病人术前应用1.5T磁共振成像(MRI)测量不同监测时间点的肿瘤体积。比较肿瘤体积变化与T降期、N分期的关系。T降期是将术后病理分期与治疗前磁共振成像临床分期进行对照。结果T降期与T未降期两组肿瘤体积平均缩小率差异无显著性意义(t=1.585,P>0.05);两组放化疗前与手术前肿瘤平均体积差异有显著性意义(t=0.007,P<0.01)。N0与N1、2两组放化疗前肿瘤平均体积差异无显著性意义(P>0.05),手术前肿瘤体积和肿瘤体积缩小率差异有显著性意义(P<0.01)。结论放化疗前肿瘤体积较大者倾向于较差的T分期。放化疗后缩小率高的直肠癌淋巴结转移阴性可能性更大。直肠癌术前放化疗肿瘤缩小率对于肿瘤T分期是否降期的预测和评估准确性较低。直肠癌术前放化疗过程的不同时间点体积变化无法准确提示肿瘤是否降期。

Objective To observe tumor volume, volume reduction rate with postoperative histopathologic tumor downstaging,lymph node status in rectal cancer after preoperative chemoradiotherapy （CRT） and to investigate the usefulness of MRI volumetry for predicting response to neoadjuvant chemoradiotherapy. Methods Forty-two patients with locally advanced rectal cancer admitted between December 2004 and October 2006 were performed preoperative CRT, followed by surgical resection. DWI volumetry was performed before and after CRT. Pre- and post CRT tumor volume and percent of volume reduction,according to postoperative T-downstaging, histopathologic lymph node staging in accordance with the AJCC TNM classification were compared. Results Eighteen patients demonstrated a tumor downstaging after chemoradiation therapy. Both pre- and post-treatment MRI tumor volumes were significantly smaller in downstaged patients than in not downstaged patients （ P 〈 0. 01 ）, but the percentage of volume reduction iates was not significantly higher in downstaged patients （ P 〉0. 05）. According to N staging,the patients were divided into NO group and N1 -2 group. There was not significant difference in mean tumor volume before preoperative CRT between NO group and N1 - 2 group （ P 〉 0. 05 ）. Conclusion The higher tumor volume reduction rate does not correlate with histopathologic downstaging,and initially smaller tumors are more likely to be downstaging tumor. So it might be unsafe to evaluate tumor response and to select the surgical method on the basis. The tumor volume before chemoradiotherapy does not correlate with histopathologic lymph node status, but the tumor volume after chemoradiotherapy and tumor volume reduction rate in patients with node-matastasis are significantly different with those in patients without node-matastasis. So the higher DWI volumetric tumor reduction rate is more inclined to have negative nodes in rectal cancer with preoperative chemoradiotherapy.