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Does the Treatment Planning Quality Evaluation Criteria Related to Patients Locoregional Recurrence in Nasopharyngeal Carcinoma?

G Qing

G Qing*, W Hu , J Wang , X Ou , L Huang , J Lu , W Zhu , Fudan University Shanghai Cancer center, Shanghai, Shanghai


TH-EF-FS1-5 (Thursday, August 3, 2017) 1:00 PM - 3:00 PM Room: Four Seasons 1

Purpose: To investigate the impact of treatment planning quality on patients’ locoregional recurrence in nasopharyngeal carcinoma. The hypothesis of this study is that patients receiving defective/inferior treatment planning, graded by RTOG 0522 criterial, have worse outcomes.

Methods: A total of 296 nasopharyngeal carcinoma patients treated with IMRT in 2009-2010 were enrolled in this study. They all completed treatments and had detail clinical diagnosis and follow-up data (e.g., fractions, duration of treatment and T/N/M stages). Among them, 66 patients were recorded with local/regional recurrence. The median follow-up time of them was 54.3 months. All NPC Patients were divided into two groups according to their prescriptions (70.4Gy and 66Gy). The dose-volume histograms (DVHs) of the treatment planning were extracted to evaluate the correlations between target DVHs and local/region recurrence. We adapted the quality-evaluation criteria of treatment planning from RTOG 0522 because of its wide application. The Kaplan-Meier analysis was performed to find the difference between local/region recurrence and no-recurrence patients.

Results: The number of patients was 157 for the prescription of 66Gy and 139 for the prescription of 70.4Gy. The doses to PTV70.4, PTV66, PTV60 and PTV54 were collected and used as an integrated parameter for evaluating the relationship between dose and locoregional recurrence. The Kaplan-Meier analysis shows no significant differences for prescription 70.4Gy (p=0.69) and prescription 66Gy (p=0.53).

Conclusion: Criteria of target volume and the dosimetrical parameter referenced from the RTOG 0522 cannot distinguish the difference between local/region recurrence and no-recurrence patients. New grading protocol may need to be found to evaluate the quality of treatment planning for NPC patients. This will be our further study.

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