Positron Emission Tomography-based Short-term Efficacy Evaluation And Prediction In Patients With Non-small Cell Lung Cancer Treated With Hypo-fractionated Radiotherapy

Objective: Although the treatment of lung cancer has improved in recent years,the 5-year survival rate remains at a low level.In addition to the improvement of treatment methods,improving the accuracy of efficacy evaluation is another key to improving survival.The current efficacy evaluation of lung cancer is mainly based on the response evaluation criteria in solid tumors version 1.1(RECIST1.1),which recommends computed tomography(CT)as the main evaluation method for efficacy evaluation.However,CT is an anatomical imaging,which not only cannot reflect the internal metabolism of the tumor,but also the manifestations of radioactive pulmonary fibrosis caused by radiotherapy on CT may lead to misjudgment of curative effect.Due to individual differences and tumor heterogeneity,the efficacy of the same tumor after the same treatment varies.Therefore,in addition to accurate efficacy evaluation,predicting whether patients will benefit from treatment is also the key to improving survival rates,identifying patients with poor efficacy in advance,and avoiding overtreatment.In summary,exploring an accurate short-term efficacy evaluation and prediction method is the key to this study.Methods: This study included a total of 30 patients with non-small cell lung cancer who were inoperable or recurred after surgery and underwent hypo-fractionated radiotherapy(HFRT)in our department from March 2015 to June 2019.All patients underwent positron emission tomography/computerized tomography(PET/CT)examination within 1 month before radiotherapy and within 6 months after radiotherapy.After fusing the PET and CT images,delineated the region of interest(ROI)in PET image with standardized uptake value(SUV)2.5 as the threshold.On CT,delineated the ROI based on clinical experience.The SUVmax and SUVmean value of the region were measured on PET,the maximum diameter and volume of the region of interest were measured on PET and CT,respectively.According to the european organization for research and treatment of cancer(EORTC),PET-based evaluate the efficacy used the relative change rate of SUVmax before and after treatment.CT is based on the RECIST1.1 standard,and the relative change rate of the largest diameter before and after treatment is used as the efficacy evaluation index.The Kaplan-Meier method was used to analyze the relationship between the efficacy evaluation of the two imaging methods and survival time.The Mc Nemar test was used to compare the difference between the two imaging methods in terms of efficacy evaluation.The PET images including the ROI were imported into the 3D Slicer software,and a total of 851 feature variables were extracted.The least absolute shrinkage and selection operator(LASSO)method was used to eliminate redundant features.The selected features were used to establish a short-term efficacy prediction model and displayed in the form of a nomogram.The area under the receiver operating characteristic curve(AUC)is used to evaluate the predictive ability of the predictive model.Results: The average survival periods of responders and non-responders assessed by PET were 28.6 months and 11.4 months(P=0.29),while the survival periods of responders and non-responders assessed by CT were 24.5months and 26,respectively Months(P=0.66).In the comparison of the efficacy evaluation of PET and CT,the objective response rates of the efficacy evaluation based on PET and CT were 70.97%(22/31)and 12.90%(4/31),(P<0.001).There was no significant difference in the volume of ROI delineated by PET and CT before treatment(P=0.337),but there were significant differences in the volume after treatment and the maximum diameter before and after treatment(all P<0.05).Whether chemotherapy or not has no effect on the efficacy evaluation of patients after HFRT(P=0.374).After LASSO regression,3 radiomics features were selected to establish a short-term efficacy prediction model,and the AUC of the model was calculated to be(0.94,95% CI 0.85-0.99,P<0.001).Conclusion: PET-based short-term efficacy has a higher objective response rate than CT-based.PET-based short-term efficacy could identify more responders.The short-term efficacy prediction model established based on PET radiomics has high accuracy.It can identify the patient’s response to the treatment before treatment and choose the best effective treatment for patients.