Dosimetric And Retrospective Clinical Study Of Intensity Modulated Radiation Therapy For Post-operative Cervical Cancer

PART I Difference and feasibility of intensity-modulated radiotherapy and conventional 2D radiotherapy for postoperative cervical cancer evaluated with ICRU83 report method[Object] To evaluate the difference and feasibility of intensity-modulated radiotherapy and conventional 2D radiotherapy for postoperative cervical cancer with ICRU83 report method.[Methods] Retrospectively analysis the DVH parameters of 10 IMRT plans and 10 conventional 2D plans simulated on the same planning CT. The DVH parameters evaluated include D100(Dmax), D98(Dnear-min), D95, D5o(Dmedia), Dmean, D2(Dnear-max), D0(Dmax) for PTV, Dmax、V40、V50、D1cc、D2cc?D2 for rectum and bladder, V10,V20,V3o for pelvic bones, V10-4o,Dmean,Dmax and D2 for small intestine.[Results]:PTV D50 is raised by 4.47±3.62% in IMRT plans than 2D plans, the actual value was 200±157cGy (t=4.2,p=0.001). V10 and V20 for pelvic bones in IMRT was higher than in 2D plans, V30 for pelvic bones in IMRT and 2D plans showed no statistical significance. V10 and V20 for small intestine was higher and V40 was lower in IMRT plans than 2D plans. V40 and Dmean was reduced in IMRT plans, while there still remains small high dose volume.[Conclusion]The method recommended by ICRU83 report is feasible. IMRT potentially increased dose to the target volume, reduced dose for bladder and rectum while small high dose volume still remain. IMRT increased low-dose volume for small intestine and pelvic bones.With D50 as a standard for dose evaluation, prescribed dose should be decreased by 4.47±3.62%.PART II Retrospective clinical study of IMRT for post-operative adjuvant radiotherapy for early-stage cervical cancer[OBJECTIVE] To study the efficacy and side effects for postopera tive adjuvant intensity-modulated radiation therapy for early stage cervical cancer, and to analyze the prognostic factors.[METHODS] Data were retrospectively analyzed from 151 patients with FIGOIA1-IIA2 cervical cancer with postoperative adjuvant radiotherapy.70 patients went through intensity-modulated radiotherapy and 81 conventional radiotherapy. OS, PFS,acute and chronic adverse effects were analyzed.[RESULTS] Conventional radiotherapy group have lower rate of pathological lymph node metastasis(16% vs 50%,p=0.000) and longer follow-up period(50.3±16.3 vs 36.9 ±14.9 p=0.00).2-year PFS was non-significant between groups(92.6% vs 95.7%, p=NS). A total of 9 recurrence were observed non-significance(7.4% vs 4.3% p=NS),including 5 cases of pelvic recurrence(4.9% vs 0%, p=0.124). Acute and chronic adverse effect rates did not show correlation with IMRT or concurrent chemotherapy. Patients with pathologic positive lymph nodes, tumor larger than 4cm, neoadjuvant chemotherapy showed unfavourable prognosis.[CONCLUSION] IMRT for post-operative adjuvant radiotherapy for early-stage cervical cancer showed favourable trend to decrease pelvic recurrence(4.9% vs 0%, p=0.124), but did not improve overall survival. Patients with pathologic positive lymph nodes, tumor larger than 4cm showed unfavourable prognosis.