Clinical Significance Of Three-dimensional Conformal Radiotherapy In Postoperative Patients With Node-positive Cervical Cancer

Objective Reduction of irradiated small bowel,rectum,blader volume, using a conformal three-dimensional treatment planning technique in postoperative radiotherapy of cervical cancer patients.Methods 1. Large gynecological treatment fields including the para-aortic nodes were analyzed in 30 patients. A conventional treatment plan with anterior and posterior (AP-PA) parallel opposed fields and a 3D 4-field conformal radiotherapy plan with a central blocking of small bowel were compared for each patient. Dose-volume histograms and dose parameters were established. 2. There are 60 postoperative patients with cervical cancer has been divided two groups randomly from 2005-02 to 2006-12, one group treated by the technique of 3D 4-field conformal radiotherapy plan, other group was treated with the conventional plan. Studied to the complication of radiotherapy and the survival rate, to contrast the effect of two technique in clinic. Results The mean Tumor Control Probablity (TCP) values for both the conventional and the conformal technique were 0.60 and 0.61, respectively, with ranges of 0.51 to 0.69and 0.54 to 0.68, respectively. The mean volume receiving 95% or more of the prescribed dose (V95) of the small bowel,rectum,blader was 40% (32.5—66.3),99% (86.3-100),98% (95.6-100) , respectively , in the AP-PA technique and in the conformal technique was 22% (14.5—25.5),24% (18.1—29.2),62% (59.1—65.3),(P<0.001 t test ) respectively. The mean Normal Tissue Complication Probability (NTCP) decreased from 0.11 to 0.03 with the conformal plan. The mean median dose to the kidneys was only slightly elevated in the conformal treatment. The mean near-minimum dose (D95) to the rectosigmoid decreased from 48.29 to 4.51 Gy in the conformal plan compared to the conventional plan. 2. The rectum complication was 35.5% in conformal group, in convention group was 61%.significantly (P<0.05) . Bladder complication was 15% and 38.7%, respectively, significantly (P<0.05) .Long-term complication were radiation proctitis and radiocystitis mainly, in the conformal technique and in conventional technique was 13.3%,10% and 36.7%,30%, respectively. significantly (P<0.05) . Conclusion The small bowel dose can be significantly reduced with 3D treatment planning, as well as rectum. This allows dose escalation to the tumor region without unacceptable toxicity for the critical organs...