Preliminary Study On The Evaluation Of Radiosensitivity And Individualized Radiotherapy For Nasopharyngeal Carcinoma By Continuous CT In Radiotherapy

Purpose:Previous studies have shown that the rate of tumor regression at the end of intensity-modulated radiotherapy is an important factor affecting the prognosis of patients with locally advanced nasopharyngeal carcinoma,and that push irradiation of residual tumor at the end of intensity-modulated radiotherapy can improve the local control rate.Since there is no universally accepted standard for radiation sensitivity evaluation of nasopharyngeal carcinoma,this study intends to propose a more objective and feasible semi-quantitative evaluation standard based on multiple consecutive CT examinations in radiotherapy,not limited to locally advanced patients,to make a more accurate assessment of radiation sensitivity of nasopharyngeal carcinoma patients.The prognosis of patients with different radiosensitivity of nasopharyngeal carcinoma and the effectiveness and long-term toxicity of radiation-resistant tumor-pushing radiotherapy will be studied through long-term follow-up.Participants and methods:From April 2011 to November 2021,all NPC patients treated with IMRT at our center were screened,and a total of 137 eligible cases were enrolled.Enrolled patients underwent positional CT before,during,and after radiotherapy and had complete follow-up information.Patients were evaluated for radiosensitivity according to our established criteria and were divided into radiosensitive,radiosensitive,and radiation-resistant groups,with some of the radiation-insensitive and resistant patients undergoing push radiotherapy.The prognosis of this group of patients and the late toxic side effects after treatment were studied.Survival rates were calculated and survival curves were plotted using the Kaplan-Meier method.Univariate and multifactorial analyses of factors associated with survival prognosis were performed by Log-rank test and Cox stepwise regression test.Results:Among radiation-resistant patients,OS,LRRFS,and DMFS were significantly higher in patients who received push radiotherapy than in those who did not receive push radiotherapy(all P < 0.05).The 5-year OS was 90.0% and 40.6%,the 5-year LRRFS was 95.2% and 80.0%,and the 5-year DMFS was 85.5.0% and 50.8% for patients in the pushed versus unpushed group,respectively.Multifactorial analysis showed that push radiotherapy was an independent prognostic factor affecting overall survival.Conclusions:Based on the evaluation of patient radiosensitivity by serially positioned CT examinations in radiotherapy,push dose radiotherapy for radiation-resistant nasopharyngeal carcinoma patients may tumor control and clinical benefit.Prompt treatment may be required for radiation-insensitive patients and warrants further prospective study.