PV QA 4 - Poster Viewing Q&A 4
TU_17_3484 - Dosimetry and Efficacy Analysis of 125I Radioactive Seeds Implantation for Cervical Cancer With Pelvic Recurrent After Radiation Therapy
Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3
Dosimetry and Efficacy Analysis of 125I Radioactive Seeds Implantation for Cervical Cancer With Pelvic Recurrent After Radiation Therapy
A. Qu, J. Wang, H. Sun, W. Jiang, Y. Jiang, and S. Tian; Peking University Third Hospital, Beijing, China
Purpose/Objective(s): To observed the efficacy of radioactive 125I seeds implantation for pelvic recurrent cervical cancer after radiotherapy, and the dosimetric parameters affecting outcome were further analyzed to guiding therapy.
Materials/Methods: A retrospective analysis was made with pelvic recurrent cervical cancer after radiotherapy from July 2005 to October 2015 in our hospital with 125I seeds implantation, under ultrasound or CT guidance. Treatment planning was performed before implantation to estimate the number, activity of the seeds. The seeds numbers ranged from 10-140 with a median numbers of 62.5, and the activity of seeds ranged from 0.5-0.8 mCi with a median activity of 0.7mCi. Dosimetric verification was performed using CT scan immediately after 125I seeds implantation. D90、D100、V100、V150、and V200 were evaluated in postoperative plan. The Kaplan-Meier method was used to calculate the local progression free survival (LPFS) rate and overall survival (OS) rate. The Log-rank test and Cox regression were used for univariate and multivariate analysis.
Results: All of the 36 patients received pelvic radiotherapy previously, 13.88%（5/36）of the patients received re-irradiation. The median dose of cumulative radiotherapy was 56 (42-107)Gy EQD2. The interval time of the last radiotherapy to I125 implantation was 12 (2-60) months. 15 cases were central recurrence (41.67%, 15/36), and 21 cases was pelvic wall recurrence (58.33%, 21/36). The median follow-up time was 11.5 months (2-30 months). Vaginal fistula occurred in 1 case. No other severe adverse effects. The downgrade rate of pain was 79.2% (19/24). The short-term local control rate was 88.9% (32/36). 1-year and 2-year LPFS rate were 34.9% and 20%, respectively. 1-year and 2-year OS rate were 52% and 19.6%, respectively. Multivariate analysis showed that the location of the recurrence，volume of lesion and D90 was significantly related to LPFS(P<0.05). And the location of the recurrence was also significantly related to OS (P<0.05). 33 cases were entered in dosimetric analysis. D90 was 128.5±47.4Gy, D100 was 50.4±23.7Gy, and V100 was 86.7%±12.9%. Univariate analysis showed that D100, D90, V100 were significantly associated with LPFS (P<0.05). D90>105Gy and <105Gy, 1-year LPFS were 53.3% and 0% (P<0.05), respectively. D100>55Gy and <55Gy, 1-year LPFS were 49.2% and 15.8% (P<0.05), respectively. V100>91% and <91%, 1-year LPFS were 55% and 15.6% (P<0.05), respectively. Multivariate analysis showed D100 was the independent factors.
Conclusion: Radioactive 125I seeds implantation was a safe, effective salvage treatment for pelvic recurrent cervical cancer after radiotherapy. It could relieve the pain for patients undergone multiple treatment after relapse. 125I radioactive seed implantation was recommended for patients with recurrent in pelvic wall, compared with recurrent in central pelvic. D100>55Gy or D90>105Gy or V100>91% could significantly improve the local control.
Author Disclosure: A. Qu: None. J. Wang: None. H. Sun: None. W. Jiang: None.